tag:blogger.com,1999:blog-78080510557487809512014-12-15T01:58:32.948-06:00Astronomy DJDiscover The Universe From Your Own BackyardDJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.comBlogger31125tag:blogger.com,1999:blog-7808051055748780951.post-10225138159290345632012-08-01T11:28:00.000-05:002012-08-01T16:39:20.269-05:00Summer Astronomy: Off The Beaten Path~ NGC 6819<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Uh0Jo_BJ8n4/UBcbBtqXRlI/AAAAAAAAAYI/QQLbIyJNjmo/s1600/800px-Paranal_Starry_Night.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="http://4.bp.blogspot.com/-Uh0Jo_BJ8n4/UBcbBtqXRlI/AAAAAAAAAYI/QQLbIyJNjmo/s400/800px-Paranal_Starry_Night.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Night scene at the 2600 metre high Cerro Paranal, <br />home of ESO’s Very Large Telescope (VLT) array.<span style="background-color: #f9f9f9; font-family: sans-serif; font-size: 12px; line-height: 19px; text-align: -webkit-auto;"><br /></span>(<a href="http://commons.wikimedia.org/wiki/File:Paranal_Starry_Night.jpg">image source</a>)</td></tr></tbody></table><br />Warm summer nights can be a real pleasure when exploring the depths of space with a telescope. The constellation of Cygnus beckons with many popular targets. &nbsp;One of my favorites in Cygnus is a little off the beaten path for some, but still very rewarding once you locate it. &nbsp;It is the open cluster NGC 6819.<br /><br />Cygnus is brimming with open clusters. &nbsp;I have viewed many of them on different occasions with different equipment. &nbsp;NGC 6819 isn't as big or bright as some, nor does it have any really bright (apparent brightness) stars to offer. &nbsp;But it's a favorite just the same...<br /><br /><br /><a name='more'></a><br />NGC 6819 lies in the plane of our Milky Way Galaxy at a distance of 7,200 light years. &nbsp;It is an intermediate age cluster of about 2.5 billion years old. &nbsp;It has a diameter of about 5' of arc visually and shines at magnitude 7.3. &nbsp;It contains upwards of 150 stars magnitudes 10-16, about two or three dozen of which are visible in a 6 to 10" telescope from even light polluted skies. <br /><br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-AIqwDAW9Pog/UBk0JTAv0JI/AAAAAAAAAYY/BVf5oRUqIA8/s1600/NGC_6819.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="433" src="http://1.bp.blogspot.com/-AIqwDAW9Pog/UBk0JTAv0JI/AAAAAAAAAYY/BVf5oRUqIA8/s640/NGC_6819.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">NGC 6819 - The Foxhead Cluster<br />(Image Credit: <a href="http://www.ancientstarlight.com/NGC6819.html" target="_blank">Drew Sullivan www.ancientstarlight.com</a>)</td></tr></tbody></table><br />NGC 6819 has the nickname "The Foxhead Cluster". &nbsp; In the heart of the cluster there is the appearance of the head of a fox angled a little away from looking right at you. &nbsp;The eyes, ears, and nose are emptier spaces outlined by stars. It is obscure for sure, but you can sometimes pick it out of an image. &nbsp;Click on the image credit link above and it will link you to the website of the author. &nbsp;Click on the image at his page and get the full size image to see if you can pick out the fox. &nbsp;It is such a good image with so many stars that it is actually more difficult to see it in the image than it can be just looking through a good telescope.<br /><br />In my 10" under fairly light polluted skies I can&nbsp;perceive&nbsp;the face of the fox, outlined by about 30 stars. It is a little easier sometimes in a telescope&nbsp;because the field isn't nearly as rich as a beautiful image can be.&nbsp; I like to start off with a lower magnification of about 85x to both find, and frame the cluster in a nice field of stars. &nbsp;Then I like to step up the power to around 170x to resolve more stars and look for the fox head&nbsp;appearance. <br /><br />NGC 6819 is located a little over midway from Eta to Delta Cygni, and a little ways west of that line towards the bright star Vega in Lyra. &nbsp;You can also draw a mental line in the sky from Gamma Cygni (the center of the cross) to Vega, and it is a little over one third of the way to Vega right on the line, a little past where it intersects the Eta-Delta line.<br /><br />Go have a look! &nbsp;I hope you enjoy it as much as I do.<br /><br />Thanks for reading!<br /><br /><br /><br /><br />DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-52714502155284796262012-07-20T09:54:00.002-05:002012-07-21T13:23:31.158-05:00Summer Astronomy: Off The Beaten Path~ NGC 6210<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-TM82omfOaew/UAh-WAFHnnI/AAAAAAAAAWQ/iYVD02qbQaQ/s1600/lossy-page1-601px-NGC_6210_HST.tif.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="397" src="http://1.bp.blogspot.com/-TM82omfOaew/UAh-WAFHnnI/AAAAAAAAAWQ/iYVD02qbQaQ/s400/lossy-page1-601px-NGC_6210_HST.tif.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">NGC 6210<br />A Planetary Nebula in Hercules<br />(<a href="http://en.wikipedia.org/w/index.php?title=File:NGC_6210_HST.tif&amp;page=1" target="_blank">image source</a>)</td></tr></tbody></table><br /><br /><br />The showpiece objects of summer are numerous. &nbsp;Naked eye, <a href="http://www.amazon.com/gp/product/B0001HKIJK/ref=as_li_tf_tl?ie=UTF8&amp;camp=1789&amp;creative=9325&amp;creativeASIN=B0001HKIJK&amp;linkCode=as2&amp;tag=astdj-20" target="_blank">binoculars </a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=astdj-20&amp;l=as2&amp;o=1&amp;a=B0001HKIJK" style="border: none !important; margin: 0px !important;" width="1" />, or a telescope can all be your observing instrument of choice for summer's most popular targets.<br /><br />In my next few posts however, we will venture off the beaten path a bit to examine a few astronomical wonders less frequented by many, but very worthwhile for viewing. Modest, <a href="http://www.amazon.com/gp/product/B003LL9RRM/ref=as_li_tf_tl?ie=UTF8&amp;camp=1789&amp;creative=9325&amp;creativeASIN=B003LL9RRM&amp;linkCode=as2&amp;tag=astdj-20" target="_blank">reasonably priced telescopes </a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=astdj-20&amp;l=as2&amp;o=1&amp;a=B003LL9RRM" style="border: none !important; margin: 0px !important;" width="1" /> will suffice for this journey, and first up is NGC 6210...<br /><span style="background-color: white;"><br /></span><br /><span style="background-color: white;"></span><br /><a name='more'></a><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-95hb1NFpKnw/UAjHcSYGVnI/AAAAAAAAAWc/03EYl1FlH6U/s1600/Her_Hercules_Star_Chart.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="579" src="http://1.bp.blogspot.com/-95hb1NFpKnw/UAjHcSYGVnI/AAAAAAAAAWc/03EYl1FlH6U/s640/Her_Hercules_Star_Chart.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://freestarcharts.com/index.php/14-guides/constellation/1" target="_blank">image source</a>)</td></tr></tbody></table><br />High overhead shortly after full darkness, the constellation of Hercules with it's familiar "keystone" asterism is easy to find. M13 and M92 are two very popular globular clusters in this constellation, and likely the most visited deep sky objects in Hercules. Another very worthwhile object that often goes overlooked though is NGC 6210.<br /><br />A little over midway between Beta and the star 51 Herculis lies the small bright Planetary Nebula NGC 6210. Using a 6 or 8" reflector without a nebula filter for the eyepiece will reveal this easily as a non-stellar object worthy of further scrutiny. The Hubble photo at the top of this post however, is NOT what you will see!<br /><br />Even at 50x it is obviously not a star. A little brighter than magnitude 9, it's smallish size (roughly half the apparent diameter of Jupiter) makes for a fairly high surface brightness. This Planetary will take high powers well. In an 8" dob you can go upwards of 200x easy and may see some decent detail from a dark site. Keep in mind, the color you see in photographs will not be visible at the eyepiece.<br /><br />You will be able to see some color though. The nebula has a definite blue-green tint that the human eye is naturally sensitive to. It emits much of it's light in the blue-green part of the spectrum. For this reason, NGC 6210 and many other Planetary Nebulae will benefit from the use of a narrow bandpass filter such as an <a href="http://www.amazon.com/gp/product/B004FJDFMC/ref=as_li_tf_tl?ie=UTF8&amp;camp=1789&amp;creative=9325&amp;creativeASIN=B004FJDFMC&amp;linkCode=as2&amp;tag=astdj-20" target="_blank">OIII</a><img border="0" src="http://www.assoc-amazon.com/e/ir?t=astdj-20&amp;l=as2&amp;o=1&amp;a=B004FJDFMC" /> or a <a href="http://www.amazon.com/gp/product/B004HGXD0M/ref=as_li_tf_tl?ie=UTF8&amp;camp=1789&amp;creative=9325&amp;creativeASIN=B004HGXD0M&amp;linkCode=as2&amp;tag=astdj-20" target="_blank">UHC</a><img border="0" src="http://www.assoc-amazon.com/e/ir?t=astdj-20&amp;l=as2&amp;o=1&amp;a=B004HGXD0M" /> filter. These serve to greatly improve contrast by filtering out light in the deep blue and red part of the spectrum of light (thus decreasing the effect of many forms of light pollution), and permitting the light from that part of the spectrum the nebula emits much of it's visible light in.<br /><br />When viewed from dark skies at higher powers, the nebula takes on a slightly four lobed appearance in my 10" dob, encompassed by a circular, hazy background of a lighter shade. &nbsp;Some say it looks a bit like a greenish turtle, but it only appears that way to me in some of the amateur photos I have seen of it. The central star will not be directly visible, but it's presence can be detected as the Planetary sharply brightens toward the middle. <span style="background-color: white;"><br /></span><br /><br />Spend a little time studying this one at different magnifications. &nbsp;Push the power up as high as it will stand. &nbsp;It grows on you. &nbsp;You won't see so much the first couple of minutes, but after about 15 minutes your eye starts to pick out detail you did not notice at first. &nbsp;After 30 minutes you become well adapted to it's brightness level and you will see a completely different object than when you first looked at it. &nbsp;Really!<br /><br />You can read more about the particulars of this nebula and the Hubble shot above <a href="http://www.spacetelescope.org/images/potw1026a/" target="_blank">here</a>.<br /><br />Thanks for reading, now go take a look!!<br /><br /><br /><br /><span style="background-color: white;"><br /></span><br /><span style="background-color: white;"><br /></span>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-31150741468876719362012-01-26T16:22:00.001-06:002012-01-28T15:48:34.858-06:00Saturn... on a Budget!<br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-8g9zECDQ4Pc/TyG2YsZ6fCI/AAAAAAAAAU4/3mG-bNpuciY/s1600/Saturn-map.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" gda="true" height="427" src="http://4.bp.blogspot.com/-8g9zECDQ4Pc/TyG2YsZ6fCI/AAAAAAAAAU4/3mG-bNpuciY/s640/Saturn-map.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Saturn System<br />(<a href="http://commons.wikimedia.org/wiki/File:Saturn-map.jpg" target="_blank">image source</a>)</td></tr></tbody></table> This is my 2nd post on one of the most popular targets for any size telescope, the ringed planet Saturn.&nbsp; For the next few months, Saturn is well placed for viewing with a telescope.&nbsp; The rings are starting to open up more, and opposition is nearing!&nbsp;&nbsp;You will find Saturn shining brightly (a bit brighter actually)&nbsp;near&nbsp;the star Spica, the brightest star in the constellation of Virgo.&nbsp; Saturn rises in the East around midnight right now, and is high in the South just before sunrise.<br /><br />Okay, so it isn't the only planet in our solar system with rings, officially, but you can see Saturn's rings easily in small telescopes. &nbsp;Which, by the way, is why we have known about them so much longer than we have known about the&nbsp;tenuous rings surrounding the other gas giants.<br /><br />In my <a href="http://www.astronomydj.com/2011/04/saturn-showpiece-of-spring.html" target="_blank">previous post about Saturn</a>, I provided a lot of general information about the planet, and what to expect when viewing it. &nbsp;In this post I will show you how to see and enjoy Saturn without breaking the bank...<br /><br /><br /><a name='more'></a><br /><br />What does "not breaking the bank" mean? &nbsp;Well, for the purposes of this article, it means spending either under $400, or even under $200!&nbsp;&nbsp;Which figure you stay under is&nbsp;up to you.&nbsp;&nbsp;All of the choices below&nbsp;will serve up cold and distant&nbsp;Saturn, right&nbsp;from your back yard.<br /><br />The&nbsp;key ingredient is&nbsp;a telescope.&nbsp; And clear skies of course.&nbsp;&nbsp;Easy, right? &nbsp;Many are the choices and almost any telescope will work well enough to show Saturn as a ringed planet, provided it is of at least decent quality. &nbsp;My <a href="http://www.astronomydj.com/p/choosing-telescope.html" target="_blank">article on telescopes</a> may help you if you are really&nbsp;new to this. &nbsp;Or, you can just read on and I'll show you what you need...<br /><br />Small telescopes of 2.4 (60mm) to 6 inches (150mm) of aperture do a very respectable job on Saturn.&nbsp; You can even get 8" of aperture in this price range, and that's a lot of scope!&nbsp;&nbsp;This is enough aperture to show considerable detail. &nbsp;If you already have a scope, great! &nbsp;The rest&nbsp;will&nbsp;still apply. <br /><br /><span style="color: #38761d;"><u>Here is a short list of requirements:</u></span> <br /><br />1. Good optical quality of the telescope is important, of course. <br /><br />&nbsp;&nbsp;&nbsp; a.&nbsp;The most bang for the buck is the 4 inch to&nbsp;8 inch range reflector telescope of Newtonian design. &nbsp;specifically, a Dobsonian telescope.<br /><br />&nbsp;&nbsp;&nbsp; b. You can opt for a refractor telescope and stay on budget in the 2.4 to 4 inch range. &nbsp;Larger than that and they are generally more expensive than the same aperture reflector would be (and more than $400).&nbsp; Hey, some people just LIKE refractors!<br /><br />&nbsp;&nbsp;&nbsp; c.&nbsp; There&nbsp;are a couple of&nbsp;Catadioptric designs, one in each&nbsp;price range, as well.<br /><br />2. Equally important is a stable mount or viewing platform.<br /><br />&nbsp;&nbsp;&nbsp; a. The Dobsonian platform is very stable and cost effective. &nbsp;Best choice for 4 to&nbsp;8 inch reflector telescopes on a budget.<br /><br />&nbsp;&nbsp; &nbsp;b. Alt/Az mounts on tripods are an option with small refractors, and some small Newtonian reflectors as well. &nbsp;Decent equatorial mounts (you have to take the time to learn how to use it properly) without electronics are also an option.&nbsp;&nbsp;Electronic drives for tracking with EQ mounts&nbsp;can be added later at some cost.<br /><br />3. You need some good quality eyepieces.<br /><br />&nbsp;&nbsp;&nbsp; a. The eyepiece/s that come with the scope are generally decent. &nbsp;Even inexpensive eyepieces are pretty good compared to what was available 30 years ago. <br /><br />&nbsp;&nbsp; &nbsp;b. You may need another eyepiece in addition to what comes with the scope, and/or maybe a Barlow lens.<br /><br />4. You need to understand a little about "seeing conditions". &nbsp;&nbsp;This part is free.&nbsp;&nbsp;I will explain what you really need to know to understand it, and provide a&nbsp;source for more detailed explanations.<br /><br /><br />Okay, let's tackle this by the numbers. &nbsp;I'll make my recommendations on equipment for&nbsp;both of the price ranges. &nbsp;<u>Keep in mind that these choices are my opinion</u>, based on what I know and love (and also&nbsp;dislike) about astronomy with a telescope. &nbsp;There are lots of other choices, I just like these best.&nbsp; Your mileage may vary.<br /><br /><br /><span style="color: #38761d;"><u>For under $200:</u></span><br /><br />You can do it respectably, but you have to aim a little lower and expect a little less. &nbsp;Here are my choices:<br /><br />Refractor design: &nbsp;<a href="http://www.telescope.com/Telescopes/Refractor-Telescopes/Refractor-Telescopes-for-Beginners/Orion-Observer-70mm-Equatorial-Refractor-Telescope/pc/1/c/10/sc/331/p/9882.uts?refinementValueIds=4694&amp;refineByCategoryId=331" target="_blank">Orion Observer 70mm EQ</a>. &nbsp;As of this writing it is on sale for $140 + shipping. &nbsp;Skip the Barlow lens on this one. &nbsp;Add a <a href="http://www.astronomics.com/main/product.asp/catalog_name/Astronomics/category_name/4SXTTARRLMWX8H3UA5Q5HNAN82/product_id/TMBP06" target="_blank">6mm TMB Planetary from Astronomics</a> instead, $50.&nbsp; Or maybe the 7mm TMB&nbsp;for the same price would get used more often because of seeing conditions (see the end of the article).&nbsp;&nbsp;Along with the&nbsp;supplied eyepieces this will give you 28x,70x, and 116x magnifications.&nbsp; This scope is also available in an Alt/Az model.<br /><br />You will read that this scope can be pushed to 180x. &nbsp;Not really. &nbsp;A 70mm Televue or Takahashi, sure. &nbsp;Not this one though. &nbsp;40x per inch of aperture is about the max you can&nbsp;reasonably expect with any telescope, normally. &nbsp;A barlow with the supplied 10mm eyepiece would give you 140x, probably too much for this scope. &nbsp;The image would be bigger, but it would be dimmer and fuzzier and you would <u>enjoy</u> 116x (or less on many nights)&nbsp;more.&nbsp;&nbsp;Really.<br /><br />Reflector design: &nbsp;Orion wins&nbsp;again. &nbsp;This time it's the <a href="http://www.telescope.com/Telescopes/Reflector-Telescopes/Reflector-Telescopes-for-Beginners/Orion-SpaceProbe-3-Equatorial-Reflector-Telescope/pc/1/c/11/sc/339/p/9843.uts" target="_blank">SpaceProbe 3 EQ</a>. &nbsp;$150 + shipping. &nbsp;Same recommendation on an extra eyepiece as above, for exactly the same reasons.&nbsp; Also available in an Alt/Az model for less money.<br /><br />Catadioptric design:&nbsp; The <a href="http://www.opticsplanet.net/celestron-90mm-maksutov-spotting-scope-package-52268-op-90mm-spotting-scope-with-trip.html" target="_blank">Celestron 90mm Maksutov Spotting Scope Package</a> W/Tripod, from Optics Planet.&nbsp; This little package is a great grab and go set up.&nbsp; Decent aperture, very good optical quality,&nbsp;with a lightweight tripod, eyepieces, and finderscope.&nbsp; At $178 shipped to your door, I don't know how long this will be around.&nbsp; They are already selling the same scope <em>without</em> the tripod and only&nbsp;one eyepiece for $209 on a different page.&nbsp; Get this one quick.&nbsp; (I may get one of these myself, just for fun--as if I don't have enough telescopes!)<br /><br /><span style="color: #38761d;"><u>Under $400:</u></span><br /><br />Refractor:&nbsp; Once again, I think Orion has the best deal with the <a href="http://www.telescope.com/Telescopes/Refractor-Telescopes/Refractor-Telescopes-with-Equatorial-Mounts/Orion-AstroView-100mm-Equatorial-Refractor-Telescope/pc/1/c/10/sc/335/p/9862.uts?refinementValueIds=4691&amp;refineByCategoryId=335" target="_blank">AstroView 100mm EQ</a>.&nbsp; You will be hard pressed to get more refractor for the money.&nbsp; The supplied eyepieces are decent plossls of 25mm and 10mm, rendering 24x and 60x.&nbsp; A 2x barlow is a good option here and when used with these eyepeices give additional powers of 48x and 120x.<br /><br />I recommend the <a href="http://agenaastro.com/meade-series-4000-126-1-25-2x-short-focus-barlow-lens.html" target="_blank">Meade Series 4000 #126 from Agena Astro</a>.&nbsp; This is a "shorty" barlow which can be either placed into the diagonal where the eyepiece normally goes (then the eyepeice into the barlow) for 2x magnification, or, the diagonal can be placed into the barlow (and the eyepeice into the diagonal as usual) for 3x magnification.&nbsp; This will give you (in effect) six eyepieces with powers of 24, 48, 60, 72, 120, and 180x.<br /><br />Catadioptric:&nbsp; My choice, the <a href="http://www.telescopes.com/telescopes/catadioptric-telescopes/vixenvmc95lmodifiedcassegraintelescopewithminiportamount.cfm" target="_blank">Vixen VMC95L Modified Cassegrain on the Mini Porta Mount</a> from telescopes.com/&nbsp;(the Hayneedle store).&nbsp;&nbsp;This little outfit is a lightweight,&nbsp;extremely portable scope and mount with&nbsp;better planetary/lunar performance than refractors in this price range, and good performance&nbsp;for deep sky targets as well.&nbsp; The only drawbacks I know of are:<br /><br />&nbsp;&nbsp; 1. &nbsp;It only comes with one eyepeice, a 25mm plossl giving you 41x.&nbsp; You will want a couple of more well chosen eyepieces for sure, which takes you over budget.<br /><br />&nbsp;&nbsp; 2.&nbsp; The knobs for slow motion control on the otherwise solid&nbsp;mount are inferior and need to be upgraded with <a href="http://www.scopestuff.com/ss_cstal.htm" target="_blank">these</a>, or something similar.&nbsp; Call and make sure they will fit the mount to be sure.&nbsp; This will take you only a little over budget.<br /><br />Reflector:&nbsp; Biggest aperture, best deal, and what I would recommend most of all the above choices in the article,&nbsp; the <a href="http://www.astronomics.com/main/category.asp/catalog_name/Astronomics/category_name/AR848BMR3BKF8M0EVXARB2FB34/Page/1" target="_blank">Astro-Tech AT8D 8" Dobsonian from Astronomics</a>.&nbsp; There is no question that&nbsp;with free shipping,&nbsp;this is the best bang for the buck period.&nbsp; $380!&nbsp; Check it out.<br /><br />The starter eyepeices of 40x and 133x should keep you busy until you can add to your set.&nbsp; The low power eyepiece is an inexpensive, but OK,&nbsp;2" diameter wide&nbsp;field design, great for many of the larger deep sky objects.<br /><br /><br /><span style="color: #38761d;"><u>Seeing Conditions</u></span><span style="color: #38761d;"><u>:</u></span><br /><br /><br />For the purposes of this article I will give a "Readers Digest" tutorial on what the term&nbsp;"seeing conditions" means to the telescope enthusiast.<br /><br />First of all, do not confuse Transparency with Seeing Conditions.&nbsp; A beautifully transparent sky will more often than not equate to poor seeing conditions.&nbsp; Conversely, a hazy sky or high, very thin clouds can provide very good seeing.&nbsp; Here's more...<br /><br />There are two types of seeing&nbsp; atmospheric, and local.&nbsp; First, Atmospheric seeing...<br />Steadiness of the atmosphere&nbsp;contributes to the amount of detail that can be seen at higher powers through a telescope, on Solar System objects and Double Stars.&nbsp; How steady the atmosphere is&nbsp;can be a result of many combining factors,&nbsp;such as the amount of water vapor, the temperature differences at altitude,&nbsp;particulate matter suspended in the atmosphere,&nbsp;and even differing wind speeds at altitude.&nbsp; <br /><br />On nights of good to excellent seeing, as much as 40x per inch of aperture is possible without compromising clarity of the image.&nbsp; That equates to about 300x in an 8" telescope.&nbsp; Typically, in all but a few locales, atmospheric conditions are rarely this good, and even average nights can be few and far between for many.<br /><br />That means that on most nights for most locations, 20-25x per inch of aperture is a normal maximum.&nbsp; More than that does not reveal more detail and is generally less enjoyable for viewing.&nbsp; In short, if you live in an area where great seeing is a rarity, those really short focal length eyepieces aren't going to see a lot of use.&nbsp; <br /><br />Atmospheric seeing does not affect Deep Sky viewing, except maybe somewhat in the case of Star Clusters.&nbsp; On nights of bad seeing, go for the faint fuzzies and clusters.<br /><br />Local seeing...<br /><br />This refers to the conditions in and around your telescope.&nbsp; Tube currents, mirror cooling/warming, observing over hot roof tops or parking lots versus a big grassy field, etcetera.&nbsp; All of these things and more can affect "local seeing" conditions.&nbsp; Unlike atmospheric seeing (besides moving to Florida or California), you can to a large extent exercise some control over local seeing problems.<br /><br />1.&nbsp; Allow sufficient cool down time for the telescope.&nbsp; The larger the scope, the longer it takes.&nbsp; This is probably&nbsp;<em>the</em> most overlooked, but fixable problem for new scope owners.&nbsp; Mirror cooling fans are essential in scopes of 8" aperture or larger in my opinion.&nbsp; You will be surprised how much steadier the images get after two hours of viewing.<br /><br />2.&nbsp; Collimation of Newtonian Reflectors, especially in f/6 and under models, is of critical importance.&nbsp; While not technically a local seeing problem, it amounts to much the same thing at the eyepiece.&nbsp; A perfectly collimated reflector will give very sharp views of the moon and planets.&nbsp; There is a reason you hear old timers in this hobby say, "a well collimated scope sure seems to&nbsp;improve the seeing conditions".&nbsp; Take the time to learn how to do it right.&nbsp; <a href="http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm" target="_blank">Here</a> is one of the best guides for beginners, I think.&nbsp; <a href="http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/2193204/page/0/view/collapsed/sb/5/o/all/fpart/1" target="_blank">Here</a> is a&nbsp;more&nbsp;advanced guide, probably the best for more advanced users with more expensive collimating equipment.<br /><br />3. Choose your observing site carefully and try to avoid observing over obvious temerature extremes.<br /><br />For much&nbsp;more about seeing conditions and how to determine what your seeing conditions are,&nbsp;check out the links on <a href="http://celestialwonders.com/articles/seeing/" target="_blank">this page</a>!<br /><br />I hope this article helps you obtain a budget minded telescope for observing Saturn this season!<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br />You may have heard you need colored filters for your eyepieces. &nbsp;They can help some, but they aren't really needed, and many people do not ever use them and are perfectly happy.DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-48951484475176572522011-12-02T14:45:00.001-06:002012-01-06T12:02:44.760-06:00Perseus: The Double Cluster & More<br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-RGJCw0_l24w/Tv4VJ5f0KRI/AAAAAAAAAUY/QC8_h86PHKc/s1600/Perseus_charta.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="532" rea="true" src="http://3.bp.blogspot.com/-RGJCw0_l24w/Tv4VJ5f0KRI/AAAAAAAAAUY/QC8_h86PHKc/s640/Perseus_charta.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Perseus<br />(<a href="http://commons.wikimedia.org/wiki/File:Perseus_charta.png" target="_blank">image source</a>)</td></tr></tbody></table>   <br /><div style="text-align: left;"></div> <br />The constellation of Perseus is a winter grouping visible after sunset&nbsp;high in the eastern sky&nbsp;during the month of January.&nbsp;&nbsp; For denizens of the northern hemisphere,&nbsp;the cold crisp nights start early and&nbsp;last&nbsp;long this time of year, and the night sky is filled with a greater number of bright&nbsp;stars than summer.<br /><br />The constellation of Perseus plays it's part in winter's dazzling display, presenting a familiar undulating "V" pattern of bright stars between the&nbsp;Andromeda, Cassiopeia,&nbsp;and Auriga constellations.&nbsp; The area in and&nbsp;around Perseus has several famous deep sky objects, many fine double stars, and one of the most famous variable stars of all.<br /><br />Let's dig into Perseus a little and uncover some of it's finer gems...<br /><br /><a name='more'></a><br /><br /><u><span style="color: #38761d;">The Premier Showpiece of Perseus:</span></u><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-Ql7iry6OFTk/Tv4Bb6ftmdI/AAAAAAAAATc/6U2aJP9lc9Q/s1600/NGC869NGC884.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" rea="true" src="http://2.bp.blogspot.com/-Ql7iry6OFTk/Tv4Bb6ftmdI/AAAAAAAAATc/6U2aJP9lc9Q/s400/NGC869NGC884.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Double Cluster<br />(<a href="http://commons.wikimedia.org/wiki/File:NGC869NGC884.jpg" target="_blank">image source</a>)</td></tr></tbody></table> First, and&nbsp;arguably one of&nbsp;the finest objects &nbsp;in the heavens is the Double Cluster, NGC 869/884.&nbsp; The Internet abounds with informative descriptions of these clusters.&nbsp; A few interesting facts include:<br /><br />1. Distance is little over 7000 light years, making it one of the more distant objects in our galaxy visible to the naked eye, even from suburban skies.<br /><br />2. Strangely, it is&nbsp;not included in Messier's famous list of non-cometary objects.<br /><br />3. Also known as Chi (NGC884,) and h (NGC869)&nbsp;Persei.&nbsp; <br /><br />4.&nbsp;Very young clusters of 13&nbsp;million years or so that appear to be moving through space together.<br /><br />5. While both clusters are composed of primarily B and A type supergiant&nbsp;stars, NGC 884 also has several red supergiants also.<br /><br />6.&nbsp;Both clusters contain over 150 stars.<br /><br /><br />Visually stunning with virtually any optical aid from binoculars to large telescopes, the Double Cluster is best viewed in wide field instruments that provide a&nbsp;one and a half&nbsp;degree or larger field of view in order to frame the clusters nicely among the background.&nbsp; Going deep with higher powers and larger apertures&nbsp;is also rewarding, and sometimes overlooked as an option just because it looks so incredible at low powers!<br /><br />The Double Cluster is easily located between&nbsp;the tip of Perseus and the W formation of Cassiopeia.&nbsp; A decent pair of binoculars is all you need to turn this fuzzy little patch into resolved stars.&nbsp; Telescopes of 60-250mm with a suitable field of view of 1.5 to 3 degrees provide the best views.<br /><br /><br /><br /><u><span style="color: #38761d;">An Association of Stars:</span></u><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-8PAOVjOaTdg/Tv4CReLboRI/AAAAAAAAATo/vC4jVMsAjdY/s1600/Alpha_Persei_Cluster.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="350" rea="true" src="http://3.bp.blogspot.com/-8PAOVjOaTdg/Tv4CReLboRI/AAAAAAAAATo/vC4jVMsAjdY/s400/Alpha_Persei_Cluster.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Mel 20- The Alpha Persei Group (Compare with the Chart Below)<br />(<a href="http://commons.wikimedia.org/wiki/File:Alpha_Persei_Cluster.png" target="_blank">image source</a>)</td></tr></tbody></table> Next we turn our attention to Alpha Perseus, and the Alpha Persei Group.&nbsp; Also referred as Melotte 20, the Alpha Persei Group is a nice collection of stars that is&nbsp;best in&nbsp;binoculars, or short focal length telescopes with very wide (3 to 4 degrees or so) fields of view.&nbsp; <br /><br />Located around and south of the star Alpha Persei, or, Mirfak, this association of stars is relatively young at 50 million years old, and is about 580 light years away.&nbsp; About 50 stars are visible in small instruments, mostly of spectral class O, B, and A.<br /><br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-5R26wKmq7n4/Tv4RTyREz9I/AAAAAAAAAT0/uyJ1sdAbZhs/s1600/Perseus_cluster_40%25C2%25B0N.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="600" rea="true" src="http://1.bp.blogspot.com/-5R26wKmq7n4/Tv4RTyREz9I/AAAAAAAAAT0/uyJ1sdAbZhs/s640/Perseus_cluster_40%25C2%25B0N.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; text-align: center;">The Alpha Persei Cluster<br />(<a href="http://commons.wikimedia.org/wiki/File:Perseus_cluster_40%C2%B0N.png" target="_blank">image source</a>)</td></tr></tbody></table><br /><u><span style="color: #38761d;">An Intriguing Planetary Nebula:</span></u><br /><br /> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Now we travel&nbsp;to the northwest corner of the constellation boundary where we find&nbsp;M76,&nbsp;a deep sky object that is definitely going to require a telescope for a decent view, along with darker skies and or a nebula filter.&nbsp; M76 has a few nicknames you will eventually run across.&nbsp; Among them are, "The Cork Nebula", "The Little Dumbbell Nebula", "The Butterfly Nebula",&nbsp;and less frequently "The Barbell".</div><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-cDyk_dUqsCc/Tv4VBmvQDeI/AAAAAAAAAUM/fc0SX8MeTl8/s1600/Ngc650_zoom.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="225" rea="true" src="http://4.bp.blogspot.com/-cDyk_dUqsCc/Tv4VBmvQDeI/AAAAAAAAAUM/fc0SX8MeTl8/s320/Ngc650_zoom.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M76 - The Little Dumbbell<br />(<a href="http://commons.wikimedia.org/wiki/File:Ngc650_zoom.jpg" target="_blank">image source</a>)</td></tr></tbody></table> M76 is about an 11th or 12th magnitude (photographic mag.)&nbsp;object in most catalogs.&nbsp; I have found it to appear brighter than this visually as is the case with most planetaries (the human eye is sensitive to the greenish-blue light they emit), and generally get fine views with an 8" SCT under even&nbsp;suburban skies.&nbsp; A narrowband nebula filter can really help make the nebula itself appear brighter and increase contrast under these conditions.<br /><br />M76 is&nbsp;classed as&nbsp;a "Bi-polar Planetary Nebula".&nbsp; It's distance&nbsp;is generally given as&nbsp;about 2500&nbsp;light years, although it could be considerably more or less, as the distances to planetary nebula are still&nbsp;uncertain for the most part.&nbsp;&nbsp;It was discovered by Pierre Mechain, Messier's assistant, in 1780.<br /><br />The "Little Dumbbell" moniker comes from a resemblance to the much larger, brighter, M27 in the constellation of Vulpecula.&nbsp; In my 8", the Cork shape seems most applicable, but I can see the Dumbbell resemblance as well.<br /><br /><br /><u><span style="color: #38761d;">Another Open Cluster of Note:</span></u><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-OKgT6VN0AsI/Tv5BJ-HkToI/AAAAAAAAAUk/A0U8-8OPcis/s1600/M34a.jpg" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="305" rea="true" src="http://2.bp.blogspot.com/-OKgT6VN0AsI/Tv5BJ-HkToI/AAAAAAAAAUk/A0U8-8OPcis/s400/M34a.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M34<br />(<a href="http://commons.wikimedia.org/wiki/File:M34a.jpg" target="_blank">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Our next object is M34, another relatively young (100 million years old)&nbsp;open&nbsp;cluster of stars located between Beta Persei, and Gamma Andromedea.&nbsp; M34 is very suitable for binoculars and low power, wide field telescopes.&nbsp; At higher powers the smaller field of view diminishes the cluster effect, spreading out the bright stars.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div> My &nbsp;5" f/5 Newtonian with a 32mm plossl eyepiece renders a 2.5 degree field of view with a magnification of 20x, perfect for a cluster like this one.&nbsp; <br /><br /><br /><br /><br /><br /><u><span style="color: #38761d;">A&nbsp;Famous Variable Star:</span></u> <br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-hxgcsfacW8I/Tv5GCar4tUI/AAAAAAAAAUw/X2g0ewOmyxU/s1600/Eclipsing_binary_star_animation_2.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="150" rea="true" src="http://1.bp.blogspot.com/-hxgcsfacW8I/Tv5GCar4tUI/AAAAAAAAAUw/X2g0ewOmyxU/s200/Eclipsing_binary_star_animation_2.gif" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Dynamics of an Eclipsing Variable Star<br />(<a href="http://en.wikipedia.org/wiki/File:Eclipsing_binary_star_animation_2.gif" target="_blank">image source</a>)</td></tr></tbody></table>  <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Now for a Variable Star, and one of the most famous variable stars at that, Algol, or Beta Persei.&nbsp; Algol was the first&nbsp;eclipsing variable star discovered, and one of the first variables known.&nbsp; An eclipsing variable star changes in brightness due to the edge on orbit of a binary star,&nbsp;the components of which pass in front of each other during their orbit as seen from earth.<br /><br />Algol is entirely observable even without optical aid.&nbsp; At a distance of 93 light years, Algol varies in brightness from magnitude 2 down to about 3.5, every 2.87 days.&nbsp; The dimming and subsequent re-brightening can be observed in one night as the entire event takes only a few hours.<br /><br />Officially "discovered" by Geminiano Montanari&nbsp;in 1667, Algol's variable nature&nbsp;was no doubt well known to ancient astronomers of several cultures, as it's name is derived from the Arabic for "Head of the Demon", or "Demon Star".&nbsp; The eclipsing nature of the variable was first postulated by John Goodricke in 1783, and was&nbsp;spectroscopically&nbsp;confirmed in 1889 by Hermann Vogel.<br /><br />Great comparison stars for determining the brightness of Algol are Gamma Andromeda to the west, shining at magnitude 2.1, and Epsilon Persei to the east at magnitude 3.&nbsp; You can find <a href="http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algol.html" target="_blank">tables online</a> that list the&nbsp;minima of Algol to plan an observation of this fine prototype of the eclipsing variable stars.<br /><br /><br /><u><span style="color: #38761d;">Some Decent Double Stars:</span></u><br /><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Theta Perseus is a fine gold and blue binary pair located west of Alpha Persei near the Andromeda border.&nbsp; Also known as Struve 296, Theta's primary is a brilliant golden color of magnitude 4.2.&nbsp; The fainter bluish companion star is easily separated in small telescopes and lies 20" of arc away at magnitude 10.&nbsp; Coordinates are 2h 45.1m, +49* 16'.<br /><br />A really nice double star is Eta Persei, or Struve 307.&nbsp; A wide separation of 28" of arc make Eta an easy double to split, it's 3.8 and 8.5 magnitude components forming a nice gold and blue contrast pair.&nbsp; Eta is located at the very tip of the constellation north of Alpha Persei.&nbsp; The coordinates are 2h 51.5m, +55* 56'.<br /><br />Our last stop is at the other end of the constellation.&nbsp; Located several degrees east of Zeta Persei in the southeast corner of Perseus are two double stars with a 5th magnitude star in between, forming a north-south line less than a full moon diameter.&nbsp; <br /><br />The southern star in the line is the double star 56 Persei, or Struve 81.&nbsp; This close pair of yellow stars is separated by only 4.2" of arc, it's components shining at magnitudes 5.9 and 8.7.<br /><br />The northern star in the three star line is Struve 533, an easier split at 19" of arc.&nbsp; the yellowish primary shines at magnitude 7.3, and the blue companion star is magnitude 8.5.<br /><br />There are many more objects in the constellation of Perseus&nbsp;for both&nbsp;visual and photographic enthusiasts, but these highlights&nbsp;are sure to bring you back again and again.<br /><br />Enjoy!<br /><br /><br /></div> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-62287693078161409512011-11-09T23:02:00.000-06:002011-11-10T12:56:14.583-06:00Taurus: Astronomy DJ Takes A Tour <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-WI1WW69A2l0/Trwa9n4BmAI/AAAAAAAAAS8/xydbc4yKsT0/s1600/800px-Pleiades_large.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="287" nda="true" src="http://2.bp.blogspot.com/-WI1WW69A2l0/Trwa9n4BmAI/AAAAAAAAAS8/xydbc4yKsT0/s400/800px-Pleiades_large.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Pleiades- "The Seven Sisters"<br />(<a href="http://en.wikipedia.org/wiki/File:Pleiades_large.jpg" target="_blank">image source</a>)</td></tr></tbody></table> <br /><div class="separator" style="clear: both; text-align: center;"></div>&nbsp;&nbsp;&nbsp;&nbsp; Taurus the Bull is a winter constellation with something to offer for everyone who ventures out into the night to view the heavens.&nbsp; But, you don't have to wait until winter to see it.&nbsp; Just stay up a little late this month to take advantage of milder temperatures, and you can enjoy it now.&nbsp;&nbsp;Naked eye, <a href="http://www.astronomydj.com/p/binoculars-for-astronomy.html" target="_blank">binoculars</a>, or <a href="http://www.astronomydj.com/p/choosing-telescope.html" target="_blank">telescopes large and small</a> will all be rewarded with sights worthy of a night out under the stars...<br /><br /><a name='more'></a><br />&nbsp;&nbsp;&nbsp;&nbsp; Sandwiched in between Perseus to the northwest and <a href="http://www.astronomydj.com/2010/09/our-universe-today-orion-constellation.html" target="_blank">Orion</a> to the southeast lies the constellation of Taurus, home to two of the richest naked eye star clusters visible.&nbsp; Along with some lesser clusters and a rather famous nebula, Taurus provides visual delights for astronomy in winter.<br /><br /><u><span style="color: #38761d;">M45: The Pleiades</span></u>&nbsp; <br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-CLs5S7eIzzU/TrrMGm-40PI/AAAAAAAAASk/Ypgd9YAwbmM/s1600/M45map.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="287" ida="true" src="http://1.bp.blogspot.com/-CLs5S7eIzzU/TrrMGm-40PI/AAAAAAAAASk/Ypgd9YAwbmM/s400/M45map.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://en.wikipedia.org/wiki/File:M45map.jpg">image source</a>)</td></tr></tbody></table><br />&nbsp;&nbsp;&nbsp; High in the eastern&nbsp;sky&nbsp;by 9pm CST, M45, also known as the Pleiades precedes the face of the Bull into the night sky.&nbsp; M45 is quite simply a spectacular open cluster.&nbsp;&nbsp;Unaided eye, binoculars,&nbsp;and wide field telescopes provide the best views.&nbsp; I include the unaided eye because it is fun to see how many stars you can count as a test of your visual acuity, if you are at a dark sky site.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; Before the advent of any kind of optical aid (or light pollution),&nbsp; some observers recorded as many as 16 stars in the cluster.&nbsp; The best I ever did was 13.&nbsp; Most people&nbsp;with good eyesight can manage 9-11 stars.&nbsp; 6 or&nbsp;7 can be seen from most suburban locations.&nbsp; As the sky brightens and the eyes get older, the number drops.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; A decent pair of 10x50 binoculars provides a stunning view.&nbsp; If you are observing from a dark enough spot you can begin to see a haze of nebulosity around the star Merope, known as NGC 1435 or the Merope Nebula.&nbsp; Many stars fill the field with a sparkling richness.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; Step up to a low power telescopic view and you will probably have your 2nd&nbsp;best rendition of M45.&nbsp; Telescopes of 80-130mm at a focal length of f/5, with 15-20x will blow you away.&nbsp; The vivid blue color of the stars live and in person&nbsp;is hard to put into words worthy of their beauty.&nbsp; The Merope Nebula can also&nbsp;be&nbsp;glimpsed&nbsp;from a very dark site.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; If you have the budget for the equipment, an 8 or 10 inch f/5 reflector with a 35mm Panoptic or 31mm Nagler eyepiece&nbsp;will give a wide enough field of view to encompass the cluster and it's nebulosity in a spectacular way.&nbsp; Major wow factor from a dark site!<br /><br /><u><span style="color: #38761d;">The Hyades Cluster</span></u><br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-3fwfUVVROhU/TrrLTZ8sqFI/AAAAAAAAASc/O024SJChVTQ/s1600/741px-HyadesStarMap.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="322" ida="true" src="http://4.bp.blogspot.com/-3fwfUVVROhU/TrrLTZ8sqFI/AAAAAAAAASc/O024SJChVTQ/s400/741px-HyadesStarMap.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Hyades <br />(<a href="http://en.wikipedia.org/wiki/File:HyadesStarMap.jpg">image source</a>)</td></tr></tbody></table> &nbsp;&nbsp;&nbsp;&nbsp; Look&nbsp;overhead on a winter night and you will&nbsp;see the V shaped asterism of the Hyades.&nbsp; In the map above, trace a line from Aldebaran to&nbsp;Gamma Tauri, then back the other direction to Epsilon Tauri.&nbsp; This naked eye cluster is one of the closest clusters of stars to our sun at 150&nbsp;light years.&nbsp;&nbsp;The bright&nbsp;orange giant&nbsp;star Aldebaran is not a member, but lies in between us and the cluster at a distance of 65 light years.&nbsp;&nbsp; <br /><br />Gamma, Delta, Epsilon, and Theta are all red giants whose color become more apparent in binoculars.&nbsp; Together they form the V shape that represents the face of the Bull.&nbsp; Because of it 5+ degree angular size, the Hyades is best viewed with binoculars.&nbsp; It is gorgeous to behold.<br /><br />Theta is also a close naked eye double separated by about a 1/10th of a degree.&nbsp; Shining at 3.4 and 3.8 magnitude, this is an easy binocular double, but it is also a good test for your eyes alone.&nbsp;&nbsp;Like the Pleiades, see how many stars you can count with just your eyes.&nbsp; I can get 10-13 stars from my home in bright suburbs on a really clear night.&nbsp; The number rises considerably from very dark sites.<br /><br /><u><span style="color: #38761d;">A Short List of Doubles</span></u><br /><br />&nbsp;&nbsp;&nbsp;&nbsp; Along with Theta, some easy doubles in Taurus include Sigma, and Kappa Tauri.&nbsp; Sigma is located a little southeast of Aldebaran.&nbsp; On the chart above it is labeled 92.&nbsp; It is also referred to as Struve 11.&nbsp; Sigma is a little&nbsp;wider than Theta, but not as bright&nbsp;at magnitudes 4.8 and 5.2.&nbsp; Kappa is located along a line from Aldebaran through Epsilon, extended about the same distance to Epsilon.&nbsp; Also known as Struve 9,&nbsp;Kappa is a triple star.&nbsp; The main components are about at wide as Theta, at magnitudes 4.4 and 5.4, and there is a third component in a different direction,&nbsp;of magnitude 11.9&nbsp;at a little less than half the separation,&nbsp;that you may or may not see depending on how dark your&nbsp;skies are.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; Many more challenging double stars await you in Taurus.&nbsp; Consult a decent star atlas like Norton's or the Cambridge Atlas, or check out my <a href="http://www.astronomydj.com/p/great-astronomy-links.html" target="_blank">links tab</a> for some online resources for nice double star lists.&nbsp; I have several nice links for doubles.<br /><br /><u><span style="color: #38761d;">M 1: The Crab Nebula</span></u><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-xwiT_fURv-M/TrwSZ8niIsI/AAAAAAAAASs/Gz1WOmrVwiw/s1600/596px-Crab_Nebula_in_Taurus.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" nda="true" src="http://3.bp.blogspot.com/-xwiT_fURv-M/TrwSZ8niIsI/AAAAAAAAASs/Gz1WOmrVwiw/s320/596px-Crab_Nebula_in_Taurus.jpg" width="318" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M 1: The Crab Nebula<br />(<a href="http://commons.wikimedia.org/wiki/File:Crab_Nebula_in_Taurus.jpg" target="_blank">image source</a>)</td></tr></tbody></table><br />&nbsp;&nbsp;&nbsp;&nbsp; On July 4th in the year 1054 A.D., a tremendous supernova lit the heavens by night, and was visible in broad daylight in fact.&nbsp; Chinese,&nbsp;Japanese, and&nbsp;Arab&nbsp;astronomers are credited with&nbsp;recording the event, although it must have been seen virtually everywhere.&nbsp; Four times as bright as the planet Venus, SN1054 remained visible during the day for almost a month, and at night for almost two years!<br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">&nbsp;&nbsp;&nbsp;&nbsp; When the star exploded, it blew out an expanding field of debris that is now called the Crab Nebula.&nbsp; It was this nebula that started off Charles Messier's famous list of the brighter deep sky objects.&nbsp; In 1758 he was searching for the return of Halley's comet and found the Crab Nebula, and mistakenly thought he had located the comet.&nbsp; As a result of this error, he started a list of non-cometary nebula so as not to make the same mistake in the future.&nbsp; He named it, M 1.</div><br />&nbsp;&nbsp;&nbsp;&nbsp; If you extend the bottom half of the V shape out past Aldebaran a ways, you will come to Zeta Tauri, a 3.5 magnitude blue giant about 400 light years away from our sun.&nbsp; M 1 lies in the same low power field about a degree north of Zeta.&nbsp; Under dark skies it can be seen with 3 inch scopes as an oblong smoky patch, barely brighter than the background sky.&nbsp; Moving Zeta out of the field once located,&nbsp;and using medium powers helps with contrasting M 1.&nbsp; In 8 to 10 inch scopes M 1 becomes less ill defined, taking on a bit of an S or Z shape.&nbsp;&nbsp; The filamentary structure seen in photographs is not visually detectable in scopes of this size.&nbsp; I find both wide and narrow bandpass filters to be of help in bringing out a greater&nbsp;angular dimension of the nebula.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; 1/2 degree directly west of M 1 lies Struve 742, a telescopic double star.&nbsp; The 7 and 7.5 magnitude components are separated by a little under 4 seconds of arc, and appear white to most observers.<br /><br /><u><span style="color: #38761d;">Two More Open Clusters</span></u><br /><br />&nbsp;&nbsp;&nbsp;&nbsp; There are many open clusters in Taurus that are somewhat faint and challenging.&nbsp; Two&nbsp;you can test your skills on with&nbsp;telescopes of 8 inches and under&nbsp;are NGC 1647 and NGC 1746.&nbsp; You will need fairly dark skies to get a decent view.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp; NGC 1647 can be found 4 degrees due east of Epsilon, about 1/2 degree southeast of the point that would form an equilateral triangle with Epsilon and Aldebaran.&nbsp; Containing about two dozen loosely scattered&nbsp;stars magnitudes 8-13, NGC 1646 needs a fairly dark sky without moonlight to see well.&nbsp; Most of it's stars are magnitude 11 and 12, and while sparse, there are several fine geometrical patterns within the cluster that make it interesting.&nbsp; A 5 inch at 30-40x frames it nicely as the cluster is a little larger than the diameter of the full moon.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-hV8kxU5FeDY/TrwUCrBjcxI/AAAAAAAAAS0/PQ5m4zYoug0/s1600/NGC1746map.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" nda="true" src="http://1.bp.blogspot.com/-hV8kxU5FeDY/TrwUCrBjcxI/AAAAAAAAAS0/PQ5m4zYoug0/s400/NGC1746map.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Map for NGC's 1647 and 1746<br />(<a href="http://commons.wikimedia.org/wiki/File:NGC1746map.png" target="_blank">image source</a>)</td></tr></tbody></table> &nbsp;&nbsp;&nbsp;&nbsp; NGC 1746 is about the same size as NGC 1647, but differs in that there are two notable concentrations of stars within the group, each with their own NGC designation.&nbsp; Use a 5 inch or larger scope at lower powers&nbsp;under dark skies for the best views.&nbsp; NGC 1750 is the western concentration within NGC1746, and is the richest part with about two dozen stars magnitude 10 and fainter.&nbsp; NGC 1758 in the eastern section of NGC1746 has about the same number of stars, magnitude 12 and fainter, but a little more concentrated.<br /><br /><u><span style="color: #38761d;">A Great Variable</span></u><br /><br />1,370 light years distant, RW Tauri is an eclipsing variable with a period of 2.76 days.&nbsp; The primary is spectral class B8 and is totally eclipsed by the K type subgiant companion as the plane of it's orbit around the primary star is seen edge on from earth.&nbsp; RW Tauri is remarkable in that the magnitude change is one of the greatest known for eclipsing variables.&nbsp; The brightness varies from magnitude 7.9 to 11.4, the entire eclipse lasts 9 hours, and totality lasts 84 minutes.<br /><br />&nbsp;&nbsp; RW is about one degree northwest of 41 Tauri, which in turn is about 8 degrees northeast of the Pleiades in the northern reaches of the constellation.&nbsp; Download a free planetarium software package to find your way around the sky.&nbsp; I have several listed on my <a href="http://www.astronomydj.com/p/great-astronomy-links.html" target="_blank">Links Page</a>, and they are all high quality, free downloads.<br /><br />Thanks for reading!DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-67955230083612737592011-09-23T16:39:00.001-05:002011-10-13T15:33:02.890-05:00The Milky Way: Part IV <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-UzHeOed3uyw/Tnzum-9dmXI/AAAAAAAAAP0/2Cj-hh38Wrc/s1600/Milkyway_pan1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="136" src="http://3.bp.blogspot.com/-UzHeOed3uyw/Tnzum-9dmXI/AAAAAAAAAP0/2Cj-hh38Wrc/s640/Milkyway_pan1.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">A Milky Way Panorama<br />(<a href="http://en.wikipedia.org/wiki/File:Milkyway_pan1.jpg">image source</a>)</td></tr></tbody></table>High overhead for mid-northern latitudes in autumn lies a treasure trove of Milky Way star fields.&nbsp; Arguably the richest of constellations for the small telescope is Cygnus, the Swan, owing to it's placement high overhead for observers in the northern hemisphere.&nbsp; Northward from Cygnus, the constellations of Lacerta, Cepheus, and Cassiopeia trace the path of the Milky Way into early winter. <br />Our first object of interest lies back in Cygnus, the finest double star for small telescopes, Albireo...<br /><br /><a name='more'></a><br /><br /><u><span style="color: #274e13;">Cygnus:</span></u><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-jKIL_BZG1As/TnzsXx4I0AI/AAAAAAAAAPw/Xq3gzO4Prl8/s1600/488px-Cygnus_IAU_svg.png" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="400" src="http://4.bp.blogspot.com/-jKIL_BZG1As/TnzsXx4I0AI/AAAAAAAAAPw/Xq3gzO4Prl8/s400/488px-Cygnus_IAU_svg.png" width="325" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Cygnus<br />(<a href="http://en.wikipedia.org/wiki/File:Cygnus_IAU.svg">image source</a>)</td></tr></tbody></table> <br />While the swan shape of Cygnus may be a bit obscure, the figure of a large cross running north to south in length&nbsp;is obvious.&nbsp; At the southern tip of the cross is the star Albireo, or Beta Cygni.&nbsp; Color perception of double stars varies greatly&nbsp;from person to person, often being romanticized&nbsp;by the use of jewels as colors, i.e., topaz, sapphire, ruby, garnet, etc.&nbsp; In a bright,&nbsp;color contrasting pair such as Albireo, the jewel like appearance is hard to deny.<br /><br />In the small telescope Albireo splits into two components of magnitude 3 and 5.5.&nbsp; The primary is a beautiful golden orange, and the dimmer secondary&nbsp;has a bright clear blue tint.&nbsp; The color contrast is striking at lower powers.&nbsp; If the two stars are a physical pair as suspected, at a distance of a little under 400 light years the apparent separation of 34" of arc equates to a minimum actual separation&nbsp;of about 55 of our solar systems lined up edge to edge, or, 400 billion miles.&nbsp; The primary is also a spectroscopic double too close for visual observation with a telescope.<br /><br />Traveling northward along the cross is one of the richest sections of the Milky Way.&nbsp; A rich field telescope with a 3 degree&nbsp;field of view used at a dark location is a real pleasure.&nbsp; Scanning around at low power and then playing around with different magnifications on interesting sights&nbsp;never gets old in this area of the sky.<br /><br />Near Gamma Cygni lies&nbsp;M29, a small, loose&nbsp;open cluster of about 20 stars magnitude 8 and fainter.&nbsp; There are NGC clusters of stars in this region that are&nbsp;at least as interesting to view, though the stars are generally fainter.&nbsp; Check out my <a href="http://www.astronomydj.com/p/great-astronomy-links.html">links page</a> to download free charting software and with a small learning curve you can find your way around the fainter showpieces.<br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-rBSFKogfrLk/TnzvlIQU_PI/AAAAAAAAAP4/uWfTEy1f6co/s1600/800px-Veil_nebula.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="213" src="http://4.bp.blogspot.com/-rBSFKogfrLk/TnzvlIQU_PI/AAAAAAAAAP4/uWfTEy1f6co/s320/800px-Veil_nebula.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">NGC 6960 The Western Veil Nebula &amp; 52 Cygni<br />(<a href="http://en.wikipedia.org/wiki/File:Veil_nebula.jpg">image source</a>)</td></tr></tbody></table> Sliding east and a little south&nbsp;along the cross is the double star 52 Cygni.&nbsp; 52 is a 4th magnitude K type star that appears distinctly orange in the telescope.&nbsp; It's 9th magnitude companion lies only 6.6" of arc away, making it somewhat difficult in small scopes due to the brightness of the primary.&nbsp; If you are blessed with remarkably dark skies, 52 Cygni marks the location of a portion of the Veil Nebula, a supernova remnant.&nbsp; The Veil is a challenging object visually, requiring ideal conditions.<br /><br />About 8 degrees north and a little east of 52 Cygni, a relatively nearby binary star can be found with a little effort.&nbsp; Known as 61 Cygni, this lovely pair of K type orange stars are at a distance of only 11 light years.&nbsp; Easy to separate with a small scope at medium powers, the two stars are nearly identical in appearance, one being slightly brighter.<br /><br />61 Cygni was chosen by F.W. Bessel in 1838 for the first successful attempt to measure the distance to a star by trigonometric parallax.&nbsp; He came up with a figure of 10.3 light years.&nbsp; The accepted distance today is 11.4 light years.<br /><br />Venturing west to the other side of the cross figure, in about a mirror location of the 61 Cygni location, you can find the naked eye multiple star Omicron (31)&nbsp;Cygni.&nbsp; This is one of my many favorites.&nbsp; This multiple looks great in binoculars, or a small telescope with a wide field.&nbsp; The primary is a bright golden color of magnitude 4.&nbsp; 338" away is a 5th magnitude blue star, and 107" away is another blue star of 7th magnitude.&nbsp; The contrasting colors make this a worthwhile and easy target.&nbsp; 31 Cygni is also an eclipsing variable star.<br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-yRCxnlK_3g8/Tnzxsy-5_0I/AAAAAAAAAP8/-d7bFNXtyIY/s1600/771px-M39a.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="248" src="http://1.bp.blogspot.com/-yRCxnlK_3g8/Tnzxsy-5_0I/AAAAAAAAAP8/-d7bFNXtyIY/s320/771px-M39a.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M39<br />(<a href="http://commons.wikimedia.org/wiki/File:M39a.jpg">image source</a>)</td></tr></tbody></table>M39 is the last stop in Cygnus.&nbsp; Located a few degrees north, and a tad east of Deneb, M39 is a very large and populous open cluster best seen with either binoculars or a very wide field telescope.&nbsp; An 80mm f/5 at low power is great. <br /><u><span style="color: #274e13;">Lacerta:</span></u><br /><br /><span style="color: black;">I usually concentrate on double star viewing while in the constellation of Lacerta.&nbsp; There are some rich Milky Way Star clouds along to Cygnus-Lacerta border though, if you have decently dark skies.&nbsp; Equipped with a chart from the link above, you can spend many hours with a 5" or 8" telescope checking out different double stars in this region.&nbsp; There are many that are worthwhile.&nbsp; Why not make a list of about 10 or 12 and go find them for yourself?&nbsp; I always feel a sense of discovery locating and observing&nbsp;double stars too faint to see with&nbsp;the unaided eye.&nbsp; Today's goto scopes make this easy, but nobody says you have to do it that way, just because you can.&nbsp; I started observing way&nbsp;before the goto era, and two of my favorite scopes are not goto anyway (yeah, 3 of them are!), so I still enjoy the find it yourself methods&nbsp;some of the time. </span><br /><br /><u><span style="color: #274e13;">Cepheus:</span></u><br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-N_SkTughtvY/TnzrYGpUK6I/AAAAAAAAAPs/38a2_T94_OA/s1600/488px-Cepheus_IAU_svg.png" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="400" src="http://2.bp.blogspot.com/-N_SkTughtvY/TnzrYGpUK6I/AAAAAAAAAPs/38a2_T94_OA/s400/488px-Cepheus_IAU_svg.png" width="325" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Cepheus<br />(<a href="http://en.wikipedia.org/wiki/File:Cepheus_IAU.svg">image source</a>)</td></tr></tbody></table> I grew up a "lone astronomer", no club affiliation, no friends or family&nbsp;that were very&nbsp;interested.&nbsp; All I had to learn from were my books and charts, and the occasional TV show on PBS.&nbsp; In short, there was nowhere for me to actually <u>hear</u> astronomical names pronounced correctly.&nbsp; I was probably in my twenties before I heard the name Cepheus pronounced correctly by someone in college.&nbsp; I felt like such an idiot.&nbsp; I'd been saying it wrong all my life.&nbsp; Turns out there were a whole lot of&nbsp;names I hadn't been&nbsp;pronouncing right!&nbsp;&nbsp;Outside of astronomy circles, they just aren't words you hear&nbsp;very often,&nbsp;if at all.&nbsp;&nbsp;And old habits die hard.&nbsp; I still have to think first&nbsp;in order not to say "globular" with a long "o" sound. &nbsp;If only that was the&nbsp;sole example.<br /><br /><span style="font-family: inherit;">Anyway, Cepheus,&nbsp;whether you pronounce it&nbsp;correctly or not, has a&nbsp;bit to offer telescopically.&nbsp; We begin with <span style="color: black;">Herschel's Garnet Star, Mu Cephei.&nbsp; Sir William Herschel so dubbed the star in 1783 when he wrote:</span></span><br /><br /><span style="font-size: x-small;">"A very considerable star, not marked by Flamstead, will be found near the head of Cepheus. Its right ascension in time, is about 2'19" preceding Flamstead's 10th Cephei, and it is about 2<sup>o</sup>20'3" more south than the same star. It is of a very fine deep garnet colour, such as the periodical star o ceti was formerly, and a most beautiful object, especially if we look for some time at a white star before we turn our telescope to it, such as <span style="font-family: symbol;">a</span> cephei, which is near at hand."</span><br /><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><span style="font-family: inherit;">In binoculars or a small telescope the deep red color of this star is best.&nbsp; The larger the telescope, the more orange the tint becomes.&nbsp; Mu Cephei is a semi-regular variable red giant with a brightness range of about 3.5 to 5.&nbsp; It may well be the largest star visible to the naked eye.&nbsp; If Herschel's Garnet Star were in the place of our sun, it's diameter would extend to beyond the orbit of the planet Saturn!&nbsp; </span></div><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-AHX3WLk63nI/TnzyxmivfbI/AAAAAAAAAQA/VFhqot1wbg8/s1600/800px-Star-sizes.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="419" src="http://4.bp.blogspot.com/-AHX3WLk63nI/TnzyxmivfbI/AAAAAAAAAQA/VFhqot1wbg8/s640/800px-Star-sizes.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Sizing Up The Denizens Of The Milky Way Galaxy<br />(Mu Cepheus is in frame 6)<br />(<a href="http://en.wikipedia.org/wiki/File:Star-sizes.jpg">image source)</a></td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><span style="font-family: inherit;">Armed with an 8" telescope, a dark sky, and&nbsp;some decent, </span><a href="http://www.astronomydj.com/p/great-astronomy-links.html"><span style="font-family: inherit;">free&nbsp;chart software</span></a><span style="font-family: inherit;">, you can explore several nice open star clusters of the NGC designation in Cepheus.&nbsp; There are many fine double stars as well.</span></div><br /><span style="font-family: inherit;">Also of particular interest is the star Delta Cephei, the prototype of Cepheid Variable stars.&nbsp; Cepheid variables pulsate and vary in luminosity like clockwork.&nbsp; The period/luminosity relationship is such that the&nbsp;absolute magnitude of the star can be determined exactly.&nbsp; An accurate distance modulus can then be determined from the difference of absolute and apparent (seen from earth)&nbsp;magnitude, allowing the distance to the star to be determined quite accurately.&nbsp; Cepheid variables are bright super giants that can be seen even in far away galaxies earning them the nickname, "measuring sticks of the universe".&nbsp; Delta Cephei is a also double star for small telescopes.</span><br /><br /><span style="color: #274e13; font-family: Arial; font-size: x-small;"><u>Cassiopeia:</u></span><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-80Uq2iiv9SI/Tnzqk1ane1I/AAAAAAAAAPo/_FHRCvbX3KE/s1600/603px-Cassiopeia_IAU_svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="377" src="http://4.bp.blogspot.com/-80Uq2iiv9SI/Tnzqk1ane1I/AAAAAAAAAPo/_FHRCvbX3KE/s400/603px-Cassiopeia_IAU_svg.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Cassiopeia<br />(<a href="http://en.wikipedia.org/wiki/File:Cassiopeia_IAU.svg">image source</a>)</td></tr></tbody></table> <span style="color: black; font-family: inherit;">My kids call Cassiopeia "the big W".&nbsp; Well, that's what it looks like!&nbsp; There are several interesting and beautiful objects for the small telescope in this Milky Way&nbsp;constellation.&nbsp; A nice double star for small to medium telescope is Eta Cassiopeia.</span><br /><br /><span style="font-family: inherit;">Eta is magnitude 3.5, an it's companion is 7.2.&nbsp; The separation varies from 5" of arc to around 16", over a 500 year period.&nbsp; The color contrast is pretty, with most seeing the primary as gold or yellow, and the secondary as reddish.&nbsp; The separation right now is about 12" of arc, making this fairly easy to spilt.</span><br /><br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-dcdH6DyMbCg/Tnzpd20oswI/AAAAAAAAAPk/udhmTF31MAc/s1600/Eclipsing_binary_star_animation_2.gif" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" hca="true" src="http://4.bp.blogspot.com/-dcdH6DyMbCg/Tnzpd20oswI/AAAAAAAAAPk/udhmTF31MAc/s1600/Eclipsing_binary_star_animation_2.gif" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://en.wikipedia.org/wiki/File:Eclipsing_binary_star_animation_2.gif">image source</a>)</td></tr></tbody></table><span style="font-family: inherit;">One of the most suitable eclipsing variables for small telescopes is RZ Cassiopeia.&nbsp; An eclipsing variable is a binary system that orbits around each other, with the plane of the orbit being edge on from earth.&nbsp; When one star passes in front of the other a change in brightness can be seen.&nbsp; In the case of RZ, The change in brightness is large enough and frequent enough&nbsp;to be easily monitored.&nbsp; Every 1.195 days the magnitude drops from 6.4 to 7.8 over a 2 hour period, then over the next two hours rises back up to 6.4!&nbsp; RZ is located within 3 degrees of Iota Cassiopeia.&nbsp; You have downloaded that charting software, right?</span><br /><br /><span style="font-family: inherit;">M52 is a fine open cluster of stars located on a line from Alpha to Beta Cassiopeia, extended&nbsp;a little further than the distance between the two stars, very close the the border with Cepheus.&nbsp; The distance to M52 is&nbsp;around 500 light years,&nbsp;and is a relatively young cluster composed of mostly type&nbsp;B giants.&nbsp; The brightest stars of the cluster are apparent magnitude 8 are type&nbsp;F &amp;&nbsp;G yellow giants.&nbsp; 50-100 stars (small scope)&nbsp;can be seen in a compressed, irregular shaped group about 8' in diameter.&nbsp;</span><br /><br /><span style="font-family: inherit;">About 1 degree from Delta Cassiopeia lies the open cluster M103.&nbsp; This is a smaller, less populous cluster in the small telescope than M52, some 8000 light years away.&nbsp; Of note is a 9th magnitude red giant, and the double star Struve 131&nbsp;located on the edge of&nbsp;the cluster, magnitudes 6 and 9, separation 14".&nbsp; The colors of the double are "straw and dusky blue", as described by Admiral Smyth in his "Cycle of Celestial Objects".</span><br /> <br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-1Fql9xhWaSo/Tnznzta9YLI/AAAAAAAAAPg/Xd9FuFWIAig/s1600/NGC457.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" hca="true" height="282" src="http://4.bp.blogspot.com/-1Fql9xhWaSo/Tnznzta9YLI/AAAAAAAAAPg/Xd9FuFWIAig/s400/NGC457.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">NGC 457<br />(<a href="http://commons.wikimedia.org/wiki/File:NGC457.jpg">image source</a>)</td></tr></tbody></table>  <br /><span style="font-family: inherit;">NGC 457 is probably my favorite open cluster in Cassiopeia.&nbsp; Also known as the "Owl" cluster, and more recently the "E.T." cluster, because it's two brightest stars appear as eyes in the figure of an owl, or E.T, like in the movie.&nbsp; No matter what you call it, it is cool to look at.&nbsp; Messier missed a really good one here!&nbsp; It is located about 4 degrees SE of Gamma.&nbsp; Phi Cassiopeia, the brightest star visible in the field, is probably not a true cluster member and only lies a little over half way to the cluster, which is some 7900 light years away.&nbsp; </span><br /><br /><span style="font-family: inherit;">Cassiopeia has many more worthwhile clusters, doubles, and variables, but this should get you started with a small to medium telescope.&nbsp; Continuing northeastward towards the constellation of Perseus a little later in the year provides for some great Milky Way scanning at lower powers.&nbsp; The Double Cluster in Perseus is fabulous!</span><br /><br /><span style="font-family: inherit;">Thanks for reading Astronomy DJ!</span>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-59017185148803745762011-08-05T16:00:00.001-05:002011-08-06T12:37:17.734-05:00The Milky Way: Part III<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-CZ9qSbIun5k/Tjwo-bcCPqI/AAAAAAAAAOw/8TzozsQSxmw/s1600/660px-Laser_Towards_Milky_Ways_Centre.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="290" src="http://3.bp.blogspot.com/-CZ9qSbIun5k/Tjwo-bcCPqI/AAAAAAAAAOw/8TzozsQSxmw/s320/660px-Laser_Towards_Milky_Ways_Centre.jpg" t$="true" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">In mid-August 2010 ESO Photo Ambassador Yuri Beletsky snapped this photo at ESO’s Paranal Observatory. A group of astronomers were observing the centre of the Milky Way using the laser guide star facility at Yepun, one of the four Unit Telescopes of the Very Large Telescope (VLT).<br />Yepun’s laser beam crosses the southern sky and creates an artificial star at an altitude of 90 km high in the Earth's mesosphere. The Laser Guide Star (LGS) is part of the VLT’s adaptive optics system and is used as a reference to correct the blurring effect of the atmosphere on images. The colour of the laser is precisely tuned to energise a layer of sodium atoms found in one of the upper layers of the atmosphere — one can recognise the familiar colour of sodium street lamps in the colour of the laser. This layer of sodium atoms is thought to be a leftover from meteorites entering the Earth’s atmosphere. When excited by the light from the laser, the atoms start glowing, forming a small bright spot that can be used as an artificial reference star for the adaptive optics. Using this technique, astronomers can obtain sharper observations. For example, when looking towards the centre of our Milky Way, researchers can better monitor the galactic core, where a central supermassive black hole, surrounded by closely orbiting stars, is swallowing gas and dust.<br />(<a href="http://commons.wikimedia.org/wiki/File:Laser_Towards_Milky_Ways_Centre.jpg">image source</a>)</td></tr></tbody></table>In part three of my Milky Way series&nbsp;we will&nbsp;slide our telescopes&nbsp;northeastward through&nbsp;Scutum and Ophiuchus, Aquila, Sagitta&nbsp;and Vulpecula.&nbsp; There is so much to see that an article of this length can&nbsp;hardly come close to covering everything, so we will&nbsp;simply be&nbsp;taking a closer look at some of my favorites.&nbsp; We will begin our tour with M16... <br /><a name='more'></a><br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-kLC-JdR1kaA/TjwuDdafjeI/AAAAAAAAAO0/klKFAhRsPgA/s1600/606px-The_Eagle_Nebula_-_GPN-2000-000987.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="316" src="http://4.bp.blogspot.com/-kLC-JdR1kaA/TjwuDdafjeI/AAAAAAAAAO0/klKFAhRsPgA/s320/606px-The_Eagle_Nebula_-_GPN-2000-000987.jpg" t$="true" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">HST image of a portion of M16<br />(<a href="http://commons.wikimedia.org/wiki/File:The_Eagle_Nebula_-_GPN-2000-000987.jpg">image source</a>)</td></tr></tbody></table> <br /><div class="separator" style="clear: both; text-align: center;"></div>M16 is a star&nbsp;birthing mass of gas and dust nicknamed the Eagle Nebula that the Hubble Space Telescope made famous several years ago&nbsp;with the above photo.&nbsp; In the image below you can see the entire complex along with the associated cluster of stars.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-8zxjS774PZk/TjwuKh8Lb4I/AAAAAAAAAO4/mB8baS63E3s/s1600/infrared+Eagle+Nebula.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://1.bp.blogspot.com/-8zxjS774PZk/TjwuKh8Lb4I/AAAAAAAAAO4/mB8baS63E3s/s320/infrared+Eagle+Nebula.jpg" t$="true" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">An unusual infrared image of M16<br />(<a href="http://www.eso.org/public/images/eso0142a/">image source</a>)</td></tr></tbody></table>In a small telescope of less than 8 inches only the star cluster is typically&nbsp;visible.&nbsp; Maybe a hazy glow of nebulosity&nbsp;can be seen.&nbsp; A better view of the nebulosity requires a larger telescope, dark skies, and maybe a narrowband filter.&nbsp;  <br />M16 can be found in&nbsp;the constellation of Serpens,&nbsp;about 3 degrees north of M17, the swan nebula.<br /><br />Moving northeast along the Milky Way we come to M26, an open cluster of about 60 stars from the 12th to 14th magnitude.&nbsp; M26 is fairly compressed being only about a sixth of a degree in diameter.&nbsp; Easily visible with a finder scope, M26 looks great&nbsp;stepped up to&nbsp;medium powers.&nbsp; I like to start with 25-30X, and work up to 100x noting the differences in appearance at different powers.&nbsp; It provides a good warm up to our next object, using the same technique.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-TungJAy_57Q/Tjw_ZqVtmtI/AAAAAAAAAO8/N5WGN15h0iA/s1600/M11.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://1.bp.blogspot.com/-TungJAy_57Q/Tjw_ZqVtmtI/AAAAAAAAAO8/N5WGN15h0iA/s320/M11.jpg" t$="true" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M11 the "Wild Duck" cluster<br />(<a href="http://commons.wikimedia.org/wiki/File:PIA07878.jpg">image source</a>)</td></tr></tbody></table> That object is...M11, the Wild Duck cluster.&nbsp;&nbsp;The moniker comes from the V-shaped&nbsp;appearance of some of the brighter cluster members,&nbsp;resembling a flock of migrating ducks pointing eastward.&nbsp; While you may or may not pick that out of the cluster, M11 never disappoints.&nbsp; It is one of the finest of all open clusters.&nbsp; It is so concentrated that it looks like a loose globular.&nbsp; Start with low power and observe the transformation as you work your way up to 100X.&nbsp; 100-150 stars from magnitude 11-14&nbsp;are visible, with a brighter 8th magnitude foreground star near the center.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-D_FhAPk0X_o/TjxPEzz-mmI/AAAAAAAAAPE/8I88QIz8pxU/s1600/284px-Ophiuchus_constellation_map_svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://1.bp.blogspot.com/-D_FhAPk0X_o/TjxPEzz-mmI/AAAAAAAAAPE/8I88QIz8pxU/s400/284px-Ophiuchus_constellation_map_svg.png" t$="true" width="355" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Ophiuchus Chart<br />(<a href="http://commons.wikimedia.org/wiki/File:Ophiuchus_constellation_map.svg">image credit</a>)</td></tr></tbody></table> A&nbsp;constellation a little over one hour of right ascension&nbsp;to the west of Scutum is Ophiuchus.&nbsp; Ophiuchus lies between the constellation/s&nbsp;Serpens Cauda and Serpens Caput and is on the western side of the Great Rift, an opaque, obscuring dust lane which divides the visible Milky way into two north/south lanes,&nbsp;and stretches from Cygnus to Centaurus.&nbsp; Several globular clusters inhabit this region.&nbsp; M9, M10, M12, and M14 are all worthy of note and visible in small telescopes.&nbsp; Their fuzzy shapes begin to resolve into individual stars in 12 inch telescopes.<br /><br />Moving north from M11, we travel&nbsp;to Altair, the alpha star of the constellation Aquila and the southern most&nbsp;component of the summer triangle, also&nbsp;comprised of Deneb in Cygnus, and Vega in Lyra.&nbsp; Aquila doesn't offer&nbsp;many individual attractions&nbsp;for the small telescope.&nbsp; There are always some good double stars to be found, and some fainter planetary nebulae abound here&nbsp;for big dob owners.&nbsp; But, if you can get to a dark location the Milky Way in Aquila is great in binoculars or wide field telescopes.&nbsp; This constellation is just east of the Great Rift along the eastern branch of the Milky Way.<br /><br />Just north of Altair lies three of my favorites.&nbsp; M71 and the constellation Sagitta, M27, and Cr399.&nbsp; M71 is an easily located globular cluster in Sagitta, the arrow.&nbsp; It's one of the few constellations that actually looks like its name.&nbsp; M71 is centered, and a little south of the line between the tip of the arrow and the center star.&nbsp; M71 begins to resolve into stars with a 6 inch telescope and though much less populated than most globulars, it is a pleasing object to observe.&nbsp; Sagitta and the surrounding area&nbsp;has many fine double stars for you to discover.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-VitEV9bYLBU/TjxN6AcB1xI/AAAAAAAAAPA/aI9L4NUY-DU/s1600/cr399+bino.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://1.bp.blogspot.com/-VitEV9bYLBU/TjxN6AcB1xI/AAAAAAAAAPA/aI9L4NUY-DU/s400/cr399+bino.png" t$="true" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Cr399, as it would appear in binoculars<br />(<a href="http://commons.wikimedia.org/wiki/File:Attaccapanni_binocolo.png">image source</a>)</td></tr></tbody></table> About 6 degrees west and a little north of M71 lies the famous asterism known as "The Coathanger" cluster, or Collinder 399.&nbsp; This a great binocular object spanning about 3 degrees in the sky.&nbsp; An 80mm f/5 refractor at very&nbsp;low power gives a fantastic view.&nbsp; It looks just like an upside down coathanger&nbsp;of brighter stars against&nbsp;the backdrop of the&nbsp;Milky Way.&nbsp; Don't waste your time with a bigger scope, you won't have a wide enough field to frame it.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-ZdVlHov4Nug/TjxWVg0L8gI/AAAAAAAAAPI/AyUc_P4PUNA/s1600/M27_Zoom.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="http://4.bp.blogspot.com/-ZdVlHov4Nug/TjxWVg0L8gI/AAAAAAAAAPI/AyUc_P4PUNA/s400/M27_Zoom.jpg" t$="true" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M27 The Dumbbell Nebula<br />(<a href="http://upload.wikimedia.org/wikipedia/commons/a/a6/M27_Zoom.jpg">image source</a>)</td></tr></tbody></table> &nbsp;Last but not least on our tour today is the spectacular planetary nebula M27, aka, the "Dumbbell" nebula, owing to&nbsp;its twin-lobed appearance resembling a partially eaten apple.&nbsp;You simply have to see it with your own eyes to believe how cool this looks, even in small telescopes.&nbsp; Pop in a decent LPR or narrowband filter and it is astoundingly attractive.&nbsp; You won't see the pretty purple and&nbsp;blue&nbsp;hues in the eyepiece that show up in time exposure photography, but there is an unmistakable greenish cast the human eye is sensitive to&nbsp;that is beautiful.&nbsp; It's big too.&nbsp; Over twice the size of M57, the "Ring" nebula in Lyra.&nbsp; And it lies in a gorgeous Milky Way field of stars with several foreground&nbsp;stars seemingly embedded in the nebula itself.<br /><br />The next installment will cover the constellations of Cygnus, Lacerta, Cepheus, and Cassiopeia,&nbsp;a Milky Way&nbsp;region more than worthy of it's own&nbsp;article.&nbsp; These four constellations are more of an autumn spectacle.<br /><br />Thanks again for reading, I hope you enjoy Our Universe Today.<br /><br /><br />&nbsp;DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-36604241014989054842011-07-07T15:19:00.000-05:002011-10-20T12:48:35.654-05:00The Milky Way: Part II <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-PhRqPrDT9ho/ThYNFO82TeI/AAAAAAAAAOc/zplhUxTstqg/s1600/sagittarius.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" m$="true" src="http://3.bp.blogspot.com/-PhRqPrDT9ho/ThYNFO82TeI/AAAAAAAAAOc/zplhUxTstqg/s320/sagittarius.png" width="310" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://commons.wikimedia.org/wiki/File:Nebomegamap.png">image source</a>)</td></tr></tbody></table> <br />If you live south of 40 degrees north latitude, you can get a very good look at one of the best constellations in the summer milky way, Sagittarius.&nbsp; A reasonably dark site, a good telescope, and the desire to explore is all you will need.&nbsp; Several nebulae, numerous open clusters and a really good globular await you.&nbsp; All are framed by the starry backdrop of distant stars that make up the milky way.<br /><br />I will introduce you to&nbsp;some of these marvelous objects here&nbsp;at Astonomy DJ,&nbsp;in the hope that you will be inspired to view them first hand and in person.&nbsp; There is truly nothing like the real thing...<br /><a name='more'></a><br />Our first stop is the constellation Sagittarius itself.&nbsp; It goes by many monikers, the Archer, the Milk Dipper, the Teapot, and&nbsp;others less common.&nbsp; Having grown up in a dark location where the cloudy appearance of the milky way was easily visible, I always liked the&nbsp;Teapot asterism designation.&nbsp; Tilted slightly as if to pour, the brighter&nbsp;star clouds of the milky way seem to rise up out of the spout like steam.<br /><br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-dizXRBX1XZ0/ThYR3kkZwTI/AAAAAAAAAOo/PU4Qa8RwAro/s1600/m8.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="267" m$="true" src="http://2.bp.blogspot.com/-dizXRBX1XZ0/ThYR3kkZwTI/AAAAAAAAAOo/PU4Qa8RwAro/s400/m8.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M8-The Lagoon Nebula<br />(<a href="http://www.eso.org/public/images/eso0936a/">image source</a>)</td></tr></tbody></table> Following the rising steam upward a little, you come to a brighter little knot of fuzziness known as M8, or the&nbsp;Lagoon Nebula.&nbsp; This is a&nbsp;fantastic object for medium to large telescopes.&nbsp;&nbsp;There is a bright open cluster of stars surrounded by a emission nebula visible in even small scopes if you&nbsp;observe from a dark location, or employ the use of a nebula filter.<br /><br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-H0aHUvCt7vI/ThYSrq21mXI/AAAAAAAAAOs/p5mOby7ZfxU/s1600/m20.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" m$="true" src="http://3.bp.blogspot.com/-H0aHUvCt7vI/ThYSrq21mXI/AAAAAAAAAOs/p5mOby7ZfxU/s320/m20.jpg" width="194" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M20-The Triffid<br />(<a href="http://www.eso.org/public/images/eso0930a/">image source</a>)</td></tr></tbody></table> Just north of M8 is another nebulous cluster, M20, or, the Triffid Nebula.&nbsp; It gets its' name from the tri-lobed&nbsp;appearance caused by darker lanes which bisect the nebula.&nbsp; Though smaller and not as bright as M8, the Triffid can be seen quite well in a 6 inch from dark skies.&nbsp; Since it is a combination emission/reflection nebula, filters&nbsp;are a toss up on this one as they tend to&nbsp;bring out the emission portion, but block the reflection part.&nbsp; Dark skies are your best friend on this one.<br /><br />Slide your scope to the east toward the star&nbsp;Lambda Sagittarius,&nbsp;the top of the Teapot.&nbsp; Just above and to the left is one of the best globular clusters period, M22.&nbsp; If it were further north, or if you lived farther south, it would easily rival M13 for top honors in the northern sky.&nbsp; Aperture is key here if you want to resolve the cluster into a myriad of stars.&nbsp; A dark and transparent night are also important due to how low in the sky it is for those north of 30 degrees latitude.<br /><br />Go back to&nbsp;Lambda and move your telescope westward&nbsp;towards M8 about half as far as you moved it to find&nbsp;M22, and you will find another of Messier's globulars, M28.&nbsp; At lower powers both Lambda and M28 will fit in the same field of view as they are less than a degree apart.&nbsp; M28 is often neglected because M22 gets all the attention.&nbsp; It is smaller and not as bright as M22, but in medium sized instruments it is a nice object.<br /><br />Just a tad north of M20 in the same low power field is M21, an open cluster of about 35 stars magnitudes 9-12.&nbsp; If you are having trouble seeing M20 because of light pollution, you can always check out M21 instead.&nbsp; There is a nice double star in the cluster.<br /><br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-TgHfm7cCeIg/ThYPB19iyXI/AAAAAAAAAOk/YEdprvxRFok/s1600/M24.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="321" m$="true" src="http://4.bp.blogspot.com/-TgHfm7cCeIg/ThYPB19iyXI/AAAAAAAAAOk/YEdprvxRFok/s400/M24.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M24 the Sagittarius Star Cloud<br />(<a href="http://commons.wikimedia.org/wiki/File:Caustiche.jpg">image source</a>)</td></tr></tbody></table>Travelling northeast&nbsp;along the milky way about three degrees, you arrive at the Sagittarius Star Cloud, also known as M24.&nbsp; Binoculars or a wide field scope such as an 80mm f/5 refractor from a dark site&nbsp;will give the best views as this is a large star cloud covering about 2x1 degrees, give or take.&nbsp; <br /><br />One and a half degrees east of M24 is another open cluster, M25.&nbsp; This is a fairly compressed cluster of stars magnitude 6-10, quite pretty.<br /><br />Just northeast of M24 is a smaller open cluster of about a dozen magnitude 9 and 10 stars, M18.&nbsp; A rather inconspicuous cluster, but worth a look.<br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-WS-4T1aOUZE/ThYOBDt6API/AAAAAAAAAOg/aPzLNAdfPkg/s1600/omegasketch.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="185" m$="true" src="http://1.bp.blogspot.com/-WS-4T1aOUZE/ThYOBDt6API/AAAAAAAAAOg/aPzLNAdfPkg/s200/omegasketch.jpg" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://commons.wikimedia.org/wiki/File:TPSMV8P287_Fig_3.jpg">image source</a>)</td></tr></tbody></table> A little further northeast along the path of the milky way is M17, a lovely emission nebula easily&nbsp;visible in even smaller telescopes.&nbsp; M17 responds very well to nebula filters.&nbsp; Also known as the Omega Nebula, and the Swan Nebula, M17 does have the shape of a swan, or&nbsp;a flattened&nbsp;number 2.&nbsp; M17 is about 5 or 6 thousand light years away.<br /><br />We will continue our trek northeastward in part III.&nbsp; Thanks for reading, now go have a look for yourself!<br /><br />DJDJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-26529354870299812682011-06-22T11:47:00.002-05:002011-10-13T15:30:29.826-05:00The Milky Way: Part I <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-49lrUT99EM8/TeRhXQMwSMI/AAAAAAAAAOA/2A0FdU6ZsXw/s1600/800px-Milky_Way_IR_Spitzer.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="http://3.bp.blogspot.com/-49lrUT99EM8/TeRhXQMwSMI/AAAAAAAAAOA/2A0FdU6ZsXw/s400/800px-Milky_Way_IR_Spitzer.jpg" t8="true" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">This dazzling infrared image from <a href="http://www.blogger.com/wiki/NASA" title="NASA"><span style="color: #0645ad;">NASA</span></a>'s <a href="http://www.blogger.com/wiki/Category:Spitzer_space_telescope" title="Category:Spitzer space telescope"><span style="color: #0645ad;">Spitzer Space Telescope</span></a> shows hundreds of thousands of stars crowded into the swirling core of our spiral Milky Way galaxy. In visible-light pictures, this region cannot be seen at all because dust lying between Earth and the galactic center blocks our view.<br />(<a href="http://commons.wikimedia.org/wiki/File:Milky_Way_IR_Spitzer.jpg">image source</a>)</td></tr></tbody></table> In this article I will detail some interesting sights of the summer Milky Way in the constellation of Scorpio.&nbsp; This southern constellation&nbsp;contain the first portions of the Milky Way to transit the meridian for northern hemisphere&nbsp;observers.&nbsp; The actual center of our Galaxy is located&nbsp;near this direction of the sky as well.<br /><br />Rich star fields, open and globular clusters, and nebulae both bright and dark are within reach of telescopes of all sizes.&nbsp; Literally something for everyone.&nbsp; To really see the Milky Way itself&nbsp;in all it's glory though, a dark sky away from light pollution is essential.&nbsp; The cloudy looking band then becomes bright against a contrasting inky blackness and it is filled with knots of brighter material,&nbsp;dark rifts and lanes, and fuzzy patches that beckon closer inspection.&nbsp; <br /><br />&nbsp;If you missed&nbsp;my intro to The Milky Way series, be sure to see my <a href="http://www.astronomydj.com/2011/05/summer-milky-way-part-i.html">previous post</a>.&nbsp; Now&nbsp;let's get on with it.&nbsp; Grab a good star chart.&nbsp; We'll start with the southwestern most portion, the first to become visible at the zenith, Scorpio...<br /><a name='more'></a><br />Scorpius is one of those few constellations that actually looks like it's name;&nbsp; a&nbsp;scorpion.&nbsp; It's distinctly scorpion shaped in fact.&nbsp; It also has some of my favorite open clusters, and a couple of globulars worth checking out.&nbsp;&nbsp;The further south you live, the higher in the sky they get, the better they look.&nbsp; From my latitude they are pretty low in the sky at their highest point, but they are still great from a dark site.<br /><br /><u><span style="color: #38761d;">M6 &amp; M7:</span></u><br /><br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-WsoNfVzSpOU/TeRiQSp48rI/AAAAAAAAAOE/6XKLG0HbF7I/s1600/800px-Open-cluster-Messier-7.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="214" src="http://1.bp.blogspot.com/-WsoNfVzSpOU/TeRiQSp48rI/AAAAAAAAAOE/6XKLG0HbF7I/s320/800px-Open-cluster-Messier-7.jpg" t8="true" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Time Exposure of M7 <br />(<a href="http://commons.wikimedia.org/wiki/File:Open-cluster-Messier-7.jpeg">image source</a>)</td></tr></tbody></table> My favorite is the M6 and M7 pair of open clusters.&nbsp; Located&nbsp;5 degrees northeast of the Scorpion's stinger, they are only&nbsp;about&nbsp;three and a half degrees apart in the sky so they are visible in the same field of view in binoculars, or really&nbsp;wide field telescopes.<br /><br />M6 is also known as the Butterfly Cluster.&nbsp;&nbsp;It is the smaller&nbsp;of the two clusters and is much further away than M7&nbsp;at a distance&nbsp;of about 1300 light years.&nbsp; At 30x - 50x in a 5-8 inch scope, the cluster is stunning.&nbsp; It still looks great in a 3 inch reflector, or an 80mm&nbsp;refractor though.&nbsp; I always thought it looked more like a bumblebee than a butterfly, but apparently I'm in the minority here.&nbsp; The brightest stars are between magnitude&nbsp;6 and 11, about 50 or so stars.&nbsp; The brightest star is a K type giant, noticably different in color than the others.&nbsp; The cluster is about 100 million years old.<br /><br />M7 lies a little over three degrees to the southeast of M6.&nbsp; Larger and brighter than M6, M7 is easily detected with the naked eye as a nebulous patch of light.&nbsp; It&nbsp;looks pretty good in&nbsp;10x50 binoculars.&nbsp; A small telescope will show it's&nbsp;80 or so stars which are 10th magnitude or brighter.&nbsp; A 6 inch or larger scope from a dark location will show a&nbsp;background dusting of much more distant&nbsp;Milky Way stars.&nbsp; M7 lies at a distance of 800 light years, and is the southernmost object to be cataloged by Messier.<br /><br /><u><span style="color: #38761d;">M4, M62, &amp; M80:</span></u><br /><br /><span style="color: black;">Three noteworthy globulars are located in Scorpio.&nbsp; Were they not so far south for those who live in northern latitudes they would no doubt be more frequently observed.&nbsp; Still, they are very interesting in their differing apparent sizes and structure.&nbsp; The bigger the telescope and the darker the sky, the finer the experience.&nbsp; They can be observed with smaller instruments though. &nbsp;I enjoy hunting them down and comparing them even with an 80mm refractor.</span><br /><br />M4 is located one and a half&nbsp;degrees due west of Antares, or Alpha Scorpii.&nbsp; At a distance of 6000 light years, M4 is one of the nearest globulars.&nbsp; A large and rather loose globular, it can begin to be resolved in a good 100mm refractor.&nbsp; It's brightest stars have an apparent magnitude of 11, and appear as a line or ridge of about 8 or 10 stars.&nbsp; For southern hemisphere observers, M4 rivals M13 in Hercules.<br /><br />M80 is a small condensed knot of decent brightness 4 degrees northwest of Antares, about midway between Alpha and Beta Scorpii.&nbsp; Easily seen in small scopes, M80 can begin to be resolved in and 8 inch.&nbsp; At a distance of about 36,000 light years, M80 is beautiful in very large scopes.&nbsp; It is very compressed, and distant.&nbsp; I can only see a few stars in my 10 inch reflector.&nbsp; Because it is so compressed it retains a high surface brightness making it a&nbsp;worthwhile object even for small scopes.&nbsp; Just don't expect a lot of detail.&nbsp; Messier thought it resembled the nucleus of a&nbsp;little comet surrounded in nebulosity.<br /><br />About 7 degrees southeast of Antares is M62, right on the border of Scorpio and Ophiuchus.&nbsp; Many modern charts list it in Ophiuchus, but I have always stuck with Scorpio.&nbsp; M62 appears a bit larger than M80, but it is harder to resolve.&nbsp; A 12 inch telescope may begin to resolve it.&nbsp; The interesting thing about M62 is it is very unsymmetrical for a globular cluster, with a markedly non-spherical shape.&nbsp; It also lies in a fairly rich Milky Way star field.<br /><br /><u><span style="color: #38761d;">NGC 6231:</span></u><br /><br /><span style="color: black;">The southern most cluster I will detail for you is NGC 6231, located just north of Zeta 1 and Zeta 2 Scorpii.&nbsp; Zeta is below Antares&nbsp;at the bottom of the scorpion's tail, where&nbsp;the tail&nbsp;bends to the east.&nbsp; NGC 6231 is often overlooked by northern hemisphere observers due to it's low position in the sky, but if you live below 40 degrees North Latitude you can get a nice view of it this time of year.&nbsp; It is superb in even small telescopes.&nbsp;</span><br /><br /><span style="color: black;">&nbsp;This is a very young cluster at just over 3 million years old, and is made up&nbsp;of mostly hot, white, O and B&nbsp;type stars.&nbsp; Zeta 1, the dimmer of the Zeta duo at apparent magnitude 4.7, is an actual cluster member and is 250,000 times as luminous at our sun.&nbsp; It is one of the most brilliant stars in our galaxy, and one of the most distant stars you can see with the naked eye.&nbsp; Zeta 2, although apparently the brighter of the duo,&nbsp;is in between us and the cluster at a distance of only 150 light years, and thus not a member of the cluster.&nbsp; NGC 6231 (and Zeta 1)&nbsp;lies at a distance of 5,700 light years.</span><br /><br /><br />In the next post I will highlight some showpiece objects in Sagittarius.&nbsp; Stay tuned...DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-70900584526740106732011-05-27T15:09:00.003-05:002011-10-13T15:28:39.754-05:00An Introduction to The Summer Milky Way<div class="separator" style="clear: both; text-align: center;"></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-amS6heMxgCE/TeEVklsriTI/AAAAAAAAAN8/tFEIj0xB-8I/s1600/lagoon.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://2.bp.blogspot.com/-amS6heMxgCE/TeEVklsriTI/AAAAAAAAAN8/tFEIj0xB-8I/s400/lagoon.jpg" t8="true" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M8 - The "Lagoon" Nebula in Sagittarius<br />(<a href="http://commons.wikimedia.org/wiki/File:M8HunterWilson.jpg">image source</a>)&nbsp;</td></tr></tbody></table>In just a couple of months the Summer Milky Way (Winter Milky Way for our southern hemisphere friends) will present itself in all it's glory in the hours after sunset.&nbsp; In order to properly enjoy it's true splendor you need a clear sky, a fairly dark location, a <a href="http://www.astronomydj.com/p/choosing-telescope.html">telescope</a>, and a willingness to explore.&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div>Actually, the telescope part is not a requirement for appreciating the Summer Milky Way, but it will greatly enhance your experience.&nbsp; A telescope exposes the treasures of the milky way in a very personal way.&nbsp; And the treasures are many and varied indeed.&nbsp; The colorful&nbsp;image of M8 above is the result of long time exposure photography.&nbsp; The associated cluster of stars and quite a bit of the nebula detail is visible in even modest size telescopes from a dark site (minus the color of course).&nbsp; The use of various <a href="http://www.astronomydj.com/p/telescope-eyepieces-5-things-you-want-3.html">nebula filters</a> can enhance the view considerably.<br /><br />Today's&nbsp;introduction will be followed with a&nbsp;three&nbsp;part series intended to help you get the most out of the upcoming encounter with the Summer Milky Way.&nbsp; It is perhaps astronomy's finest seasonal event, so let's get prepared...<br /><br /><a name='more'></a><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-L8EsxztV6Q4/Tc8t_TWsjVI/AAAAAAAAANc/MmCdM4HX4xg/s1600/M6a.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" j8="true" src="http://4.bp.blogspot.com/-L8EsxztV6Q4/Tc8t_TWsjVI/AAAAAAAAANc/MmCdM4HX4xg/s320/M6a.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M6 The Butterfly Cluster<br />(<a href="http://commons.wikimedia.org/wiki/File:M6a.jpg">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div>I think my fondest memories with a telescope are as a youngster under the Summer Milky Way.&nbsp; I was lucky to live&nbsp;on the southern edge of&nbsp;a very small town in Wisconsin.&nbsp; I had an unobstructed southern view down to the horizon, and magnitude 6 skies.&nbsp; I had an optically&nbsp;good 3 inch f/10 reflector, on a really&nbsp;crappy&nbsp;alt/az mount, and very little else except a desire to explore the heavens. <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">It was then, and is now, my favorite time of year for astronomy.&nbsp; I know&nbsp;considerably more about what I'm looking at now than I did then, and I have much better (and much more)&nbsp;equipment.&nbsp;&nbsp;Over 40 years has gone by, yet&nbsp;when I look through my big expensive telescope at a Milky Way&nbsp;cluster of stars,&nbsp;or a&nbsp;diffuse&nbsp;nebula, I&nbsp;am taken&nbsp;back to a simpler time when the wonder and joy was new and fresh, and I&nbsp;was only 11 years old.&nbsp; I become "me" again.&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><u><span style="color: #38761d;">A Little Perspective:</span></u><br /><br /><span style="color: black;">Our galaxy is around 100,000 light years across and roughly 10,000 light years thick near the hub.&nbsp; Picture&nbsp;it as a giant frisbee with a thickened middle.&nbsp; Most (but not quite all)&nbsp;of the stars you can see without optical aid are less than a thousand light years away, about 5,000 total, give or take.&nbsp; There are probably around two hundred billion stars in the Milky Way galaxy.&nbsp; The nearest galaxy similar to ours in size and shape is the Andromeda galaxy at a distance of 2.4 million light years.&nbsp; There are billions of&nbsp;galaxies, the furthest known being some 13-14 billion light years away.&nbsp; There are far more stars in the known universe than there are grains of sand on all the beaches of earth combined.&nbsp; Really.</span></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div> <br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-dCaJrAGD0NA/Tc8xx4_GlnI/AAAAAAAAANs/ch9n8SUZFkM/s1600/480px-Our_Milky_Way_Gets_a_Makeover_%2528NASA%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" j8="true" src="http://4.bp.blogspot.com/-dCaJrAGD0NA/Tc8xx4_GlnI/AAAAAAAAANs/ch9n8SUZFkM/s640/480px-Our_Milky_Way_Gets_a_Makeover_%2528NASA%2529.jpg" width="512" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Where We Are in the Milky Way Galaxy<br />&nbsp;Almost every star you can see with the unaided eye&nbsp;is within the first circle around&nbsp;our sun.<br />(<a href="http://commons.wikimedia.org/wiki/File:Our_Milky_Way_Gets_a_Makeover_(NASA).jpg">image source</a>)</td></tr></tbody></table> <br />You can see from the depiction above where our sun is located in our galaxy.&nbsp; The depiction above shows what our galaxy would look like "face on", from a vantage point of a couple hundred thousand light years away.&nbsp; Within this giant&nbsp;swirlling whirpool of stars, dust, and gas, it takes around 200 million years for our sun to complete one circuit&nbsp;around the center.&nbsp; Seen edge on from a similar distance, the Milky Way would appear as a disk shape with a thicker central bulge, much like the galaxy below.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-40cMpb9OTpQ/Tc804k2bclI/AAAAAAAAANw/OXUOZZce6lc/s1600/579px-NGC_5775.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" j8="true" src="http://1.bp.blogspot.com/-40cMpb9OTpQ/Tc804k2bclI/AAAAAAAAANw/OXUOZZce6lc/s320/579px-NGC_5775.jpg" width="308" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">HST Image of NGC 5775 <br />(<a href="http://commons.wikimedia.org/wiki/File:NGC_5775.jpg">image source</a>)</td></tr></tbody></table>The&nbsp;milky band of light&nbsp;we see stretching&nbsp;overhead&nbsp;from a dark location in July is kind of like the image above, only from the inside looking out instead.&nbsp;It&nbsp;results from&nbsp;a perspective of being located in the disk of our galaxy, about midway out from the center, and looking edgewise through the disk towards the center.&nbsp; In the January we are looking in the opposite direction through less stuff&nbsp;(away from the center)&nbsp;and the milky band of our galactic disk appears fainter and less rich.&nbsp; From a very dark location the winter milky way can be readily visible, however.<br /><br /><u><span style="color: #38761d;">Viewing the Summer&nbsp;Milky Way:</span></u><br /><br />I think the name we have for our galaxy is so poetic.&nbsp; "The Milky Way".&nbsp; So much better than it could have been, for sure.&nbsp; The brightest part of the&nbsp;Milky Way in summer stretches from the constellation Cygnus overhead, through Sagittarius low in the south.&nbsp; The Sagittarius portion transits the meridian a couple of hours earlier than the Cygnus region, as the path of the Milky Way runs from the&nbsp;SSW to NNE, not due north and south.&nbsp; <br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-VLCTNeS_VyE/TeAALvRKfnI/AAAAAAAAAN0/fjtBH6z1Ug8/s1600/Sagittarius-teapot-asterism.jpg" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="160" src="http://3.bp.blogspot.com/-VLCTNeS_VyE/TeAALvRKfnI/AAAAAAAAAN0/fjtBH6z1Ug8/s200/Sagittarius-teapot-asterism.jpg" t8="true" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://en.wikipedia.org/wiki/File:Sagittarius-teapot-asterism.jpg">image source</a>)</td></tr></tbody></table> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-REzMxF0N38s/TeAA_LqMg1I/AAAAAAAAAN4/KEGGBwz178g/s1600/800px-Sagittarius_constellation_detail_long_exposure.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="132" src="http://3.bp.blogspot.com/-REzMxF0N38s/TeAA_LqMg1I/AAAAAAAAAN4/KEGGBwz178g/s200/800px-Sagittarius_constellation_detail_long_exposure.jpg" t8="true" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">A Picture of the "Teapot" Asterism<br />in Sagittarius<br />(<a href="http://en.wikipedia.org/wiki/File:Sagittarius_constellation_detail_long_exposure.jpg">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The Scorpio/Sagittarius region is where we will begin in Part I, since this area is well placed for viewing first.&nbsp;&nbsp;With Part II,&nbsp;we will explore the Serpens-Aquila region.&nbsp; Finally, in Part III&nbsp;we will examine the Vulpecula-Cygnus area of the Milky Way.&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Along the way we will take a few side trips to some worthwhile targets that lie near the Milky Way's arc through the sky.&nbsp; They are some of summer's favorite astronomical sights and should not be missed.&nbsp; This&nbsp;upcoming three&nbsp;part series will by no means cover all the sights of the Summer&nbsp;Milky Way, or even close.&nbsp; But, it just might pave the way for some deeper exploration of your own.&nbsp; Stay tuned for Part I.</div><br /><br /><br /><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-33453136278656174492011-04-25T00:02:00.002-05:002011-10-13T15:27:00.037-05:00Globular Clusters For Spring <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-Ojy0a9oUhkw/TaHk7BIiH9I/AAAAAAAAANI/o378UOBYYDs/s1600/791px-M3LRGB_891x674.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="301" r6="true" src="http://2.bp.blogspot.com/-Ojy0a9oUhkw/TaHk7BIiH9I/AAAAAAAAANI/o378UOBYYDs/s400/791px-M3LRGB_891x674.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M3 in the constellation Canes Venatici<br />(<a href="http://commons.wikimedia.org/wiki/File:M3LRGB_891x674.jpg">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Surrounding our Milky Way galaxy is a sphere-shaped halo of a specific type of star cluster, namely, Globular Clusters (pronounced "glob", not "globe").&nbsp; They vary in size, distance and direction from the galactic center and contain the oldest stars in our galactic system.&nbsp; Around 13 billion years old in some cases!&nbsp; </div> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">If you are the owner of a small telescope,&nbsp;globulars are a good reason to&nbsp;upgrade to&nbsp;a larger telescope because they are absolutley&nbsp;one of the most beautiful sights you will ever have a chance to see.&nbsp; Check out <a href="http://www.astronomydj.com/p/big-telescopes-what-to-buy.html">my article</a> on&nbsp;what to consider when&nbsp;before&nbsp;you take the plunge and lay out big bucks for a bigger scope.&nbsp; You'll be glad you did...<br /><a name='more'></a></div><br />Not that you can't see globular clusters with a <a href="http://www.telescope.com/Orion-AstroView-90mm-Equatorial-Refractor-Telescope/p/9024.uts">3 to 4" telescope</a>, you most certainly can.&nbsp; Many, in fact.&nbsp; In scopes of this size they will look like a very interesting circular, cloudy patch&nbsp;of fuzz, brighter towards the middle.&nbsp; You can tell there is a lot more to it, but beyond a little mottling you are left to imagine.&nbsp; Globulars with telescopes in the 3-4" range are still pretty cool looking though, and&nbsp;you will notice&nbsp;differences between them that are readily apparent.<br /><br />If you want to resolve a globular cluster into individual stars you will need a little more firepower.&nbsp; A <a href="http://www.telescope.com/Telescopes/Dobsonian-Telescopes/Build-A-Scope-Dobsonians/pc/1/c/12/31.uts">6-8" telescope</a>&nbsp;can begin to show you some stars in several clusters,&nbsp;but&nbsp;an 8" or larger scope&nbsp;can really open up this area of astronomy.&nbsp; A dark location&nbsp;and moonless night are essential for the best views possible with a given aperture telescope.&nbsp; My 10" reflector&nbsp;under a dark sky will give amazing images of the best globulars, and do a pretty good job on&nbsp;a lot of the smaller, fainter ones too.<br /><br />With globular clusters (and galaxies), it is really all about aperture.&nbsp; Many claim this for all areas of visual astronomy and it is true that <em>there is no substitute for aperture</em>,&nbsp;but I have always felt like smaller telescopes can be just fine for many astronomical targets.&nbsp;&nbsp;Sure, bigger is better, but there are still worthwhile subjects&nbsp;among open clusters, nebulae, planets, and double stars&nbsp;for the smaller scopes.&nbsp; Some of the prettiest open clusters won't even fit in the field of view of my 10" reflector!<br /><br />Globulars and galaxies are a little different.&nbsp; Smaller scopes&nbsp;can reveal them, and even make them very interesting, but that's&nbsp;about it.&nbsp; You just aren't going to get the "ooh's and aah's"&nbsp;without some serious size, and the bigger the better.&nbsp; If you are thinking about getting a bigger scope (check out <a href="http://www.our-http//www.astronomydj.com/p/big-telescopes-what-to-buy.html">my article</a> first, then decide), there's no time like the&nbsp;next few months.&nbsp;&nbsp;Some of the best globulars&nbsp;will be&nbsp;visible this summer.&nbsp;&nbsp;There is a reason people catch "aperture fever" in this hobby.&nbsp; It is easy to catch!<br /><br />Here are a few&nbsp;globular clusters for&nbsp;April and May listed&nbsp;below.<br /><br /><u><span style="color: #38761d;">Globular Clusters for April/May:</span></u><br /><br /><span style="color: black;">M3-&nbsp; Located in the Constellation Canes Venatici, M3 is the most spectacular globular visible right now.&nbsp; It reigns as one of the top 3-5 best at any time, depending on personal tastes and geographical location.</span><br /><br />M53-&nbsp; About 10 degrees south and a few degrees west of M3 you will find M53&nbsp;a really nice globular in&nbsp;larger scopes.&nbsp; In an 8 incher under dark skys, the outer edges are resolved into glittering stardust.&nbsp; The inner core&nbsp;is a blaze of tightly packed glory, unresolvable&nbsp;but really cool looking non the less.<br /><br />M5-&nbsp; The latest of rising globular for spring is M5. &nbsp;M5 is a magnificent globular, period.&nbsp; Located a little over 20 degrees southeast of M3 and M53, M5&nbsp;begins to become&nbsp;spectacular in 6 to 8 inch telescopes.&nbsp; It is one of the top 5 globulars&nbsp;(in my opinion) &nbsp;for northern latitude observers.<br /><br />In a couple of short months (or, if you stay up into the wee hours of morning) there will be a veritable&nbsp;gold mine of globulars to keep you going throughout summer.&nbsp;&nbsp;Globular cluster season in just around the corner, so get&nbsp;ready.&nbsp; There is still plenty of time to upgrade to a <a href="http://www.astronomydj.com/p/big-telescopes-what-to-buy.html">larger telescope</a>!<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-O_aWszjBpIc/TbT_yvvE3EI/AAAAAAAAANM/35vyujfFF2A/s1600/800px-Globular_Cluster_M92-2006.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="268" i8="true" src="http://1.bp.blogspot.com/-O_aWszjBpIc/TbT_yvvE3EI/AAAAAAAAANM/35vyujfFF2A/s400/800px-Globular_Cluster_M92-2006.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Globular Cluster M 92 in Hercules<br />(<a href="http://commons.wikimedia.org/wiki/File:Globular_Cluster_M92-2006.JPG">image source</a>)</td></tr></tbody></table> <br />I hope this inspires you to start viewing the globulars of spring.&nbsp; The summer milky way brings many, many more to explore.&nbsp; All different in some ways, all fun to observe.<br /><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-27263851275787759292011-04-08T13:53:00.005-05:002011-10-20T12:53:52.332-05:00Double Stars For SpringAstronomy DJ&nbsp;takes a look at some popular Double Stars visible this time of year. &nbsp;In this article we will look at some double and multiple systems that can be located with the eye, and studied with small to medium size telescopes.<br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-w4u2gZZDnPg/TZ9T9y1zF2I/AAAAAAAAAM8/enOyLphFatQ/s1600/800px-Sirius_A_and_B_artwork.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" r6="true" src="http://2.bp.blogspot.com/-w4u2gZZDnPg/TZ9T9y1zF2I/AAAAAAAAAM8/enOyLphFatQ/s320/800px-Sirius_A_and_B_artwork.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">This picture is an artist's impression showing how the binary star system of Sirius A and its diminutive blue companion, Sirius B, might appear to an interstellar visitor.<br />(<a href="http://commons.wikimedia.org/wiki/File:Sirius_A_and_B_artwork.jpg">image source</a>)</td></tr></tbody></table><br />Our Milky Way galaxy is estimated to have around 300 billion stars, spread out over a disc shape 100,000 light years in diameter and 10,000 light years thick at the hub.&nbsp;&nbsp;Yet you can only&nbsp;see about 2000+ stars with your unaided eye on a given night.&nbsp;&nbsp;Of these stars, more than half are binary/multiple stars...<br /><a name='more'></a><br /><span style="color: #38761d;"><u>Stars That Make Up Our Galaxy</u></span><br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-aaeqC-LWtqs/TZ9U-mu81EI/AAAAAAAAANA/O0RE7MLineM/s1600/600px-Milky_Way_Galaxy.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" r6="true" src="http://2.bp.blogspot.com/-aaeqC-LWtqs/TZ9U-mu81EI/AAAAAAAAANA/O0RE7MLineM/s320/600px-Milky_Way_Galaxy.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Artist Conception of our Milky Way Galaxy<br />(<a href="http://commons.wikimedia.org/wiki/File:Milky_Way_Galaxy.jpg">image source</a>)</td></tr></tbody></table> About 85% of&nbsp;all the stars in our galaxy (250 billion)&nbsp;are red dwarf stars.&nbsp; About 25% of these (60 billion)&nbsp;are binary systems.&nbsp;&nbsp;The remaining 15% of stars (45 billion), including our sun,&nbsp;are larger and brighter than red dwarfs.&nbsp; A little over half of these (25 billion) are binaries.&nbsp; No one really knows why larger, hotter stars tend to have companion stars more often than red dwarfs do.<br /><br /><span style="color: #38761d;"><u>How&nbsp;Many Doubles?</u></span><br /><br /><span style="color: black;">The short answer, probably around 90 billion in our Milky Way galaxy.&nbsp; How many of the stars visible to the eye are multiple systems...?</span><br /><br /><u>The stars you can see</u>&nbsp;(maybe 6000 total, 2000+ on a given night) without the&nbsp;optical aid of <a href="http://www.our-universe-today.com/p/binoculars-for-astronomy.html">binoculars</a> or a <a href="http://www.our-universe-today.com/p/choosing-telescope.html">telescope</a>, are the&nbsp;relatively nearby (within about 3000 light years) brighter stars of the 15% group. Since over half of this group are&nbsp;binaries, there are about 1000 doubles on a given night&nbsp;whose primary star is bright enough to detect with just your eyes.&nbsp; Only a very&nbsp;few "nearby"&nbsp;red dwarfs are visible to the eye, just&nbsp;barely.&nbsp;&nbsp;Think about that for a second.&nbsp; Your eyes alone&nbsp;can detect at best,&nbsp;the&nbsp;nearest 6000&nbsp;of the 45 billion brighter stars of our galaxy, and almost none of the 255 billion red dwarf stars.&nbsp; Wow.<br /><br /><span style="color: #38761d;"><u>Observing Doubles</u></span><br /><br /><span style="color: black;">One thing I have learned over the years is that people have differing perceptions of the colors of the stars in multiple systems.&nbsp; The true color of a star is tied to it's spectral class and luminosity, but each person's eye is different and&nbsp;individual perception varies greatly.&nbsp; A double who's components are spectrally white and yellow, for example, may appear as both white to some, white and blue to some one else, bright blue and light green to another.&nbsp; Or, an orange star may appear&nbsp;decidedly red to your eye.&nbsp; You get the idea.&nbsp; The fun lies in looking for yourself and finding out how it looks to you.</span><br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-jLaHwicYRBE/TZ9ZBU6vZWI/AAAAAAAAANE/xNfHnhApHmk/s1600/800px-Morgan-Keenan_spectral_classification.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="145" r6="true" src="http://1.bp.blogspot.com/-jLaHwicYRBE/TZ9ZBU6vZWI/AAAAAAAAANE/xNfHnhApHmk/s400/800px-Morgan-Keenan_spectral_classification.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Morgan-Keenan Spectral Classification<br />(<a href="http://en.wikipedia.org/wiki/File:Morgan-Keenan_spectral_classification.png">image source</a>)</td></tr></tbody></table> <span style="color: #38761d;"><u>A Short List of Doubles&nbsp;For Spring</u></span><br /><br />Since the stars you see on a clear night belong to the larger brighter group, about half of the stars you see when you look up&nbsp;are actually double stars.&nbsp; While many of these&nbsp;require larger scopes to "split the double",&nbsp;there are still a large number of doubles&nbsp;for owners of smaller scopes.&nbsp; Several of these are quite beautiful.&nbsp; Here is a list of some of my favorite double/multiple stars visible this time of year&nbsp;for telescopes ranging in size from 3-10 inches.&nbsp; These are all visible now,&nbsp;if you are&nbsp;willing&nbsp;stay up later for a few of them.&nbsp; A finder scope may be needed for some of these if you live in suburban skies.<br /><br /><span style="color: #38761d;"><u>Zeta UMa</u></span><span style="color: black;">&nbsp;&nbsp;&nbsp; Magnitude 2.3-4.0 Sep 14".&nbsp; A famous double star systym in Ursa Major.&nbsp; Find the Big Dipper and look at the star in the bend of the handle.&nbsp; It is a visual double named Mizar and Alcor, beautiful in binoculars.&nbsp; Mizar, the brighter of the two visual stars,&nbsp;is the telescopic double.&nbsp; 50x will frame it all nicely and split the double.&nbsp; My 80mm f/5 refractor at 60x gives a gorgeous view.</span><br /><br /><span style="color: #38761d;"><u>Gamma Leonis</u></span><span style="color: black;">&nbsp;&nbsp; Magnitude 2.2-3.5 Sep 4.4".&nbsp; Also designated 41 Leonis, Gamma is a beautiful double star in the constellation Leo.&nbsp; Look for the familiar sickle shape or backward question mark asterism high overhead around 10pm in April.&nbsp; Regulus (Alpha Leonis) is the brightest star at the southern tip of the question mark shape.&nbsp; Two stars up and to the left is Gamma, the second brightest of the group.&nbsp; This is a tight binary in small scopes.&nbsp; 90x will just divide the two orange looking stars.&nbsp; Spectrally they are yellow/orange and yellow, but they both appear orange with the fainter one a lighter shade in my 5" Celestron.&nbsp; </span><br /><br /><span style="color: #38761d;"><u>Alpha Leonis</u></span><span style="color: black;">&nbsp;&nbsp; Magnitude 1.4-7.7 Sep 177".&nbsp;&nbsp;Aslo known as Regulus, "The Kingly Star".&nbsp; See Gamma Leonis for directions to finding Regulus.&nbsp; With a seperation of about 3', Regulus and it's fainter companion can be see with 10x50 binoculars.&nbsp; Spectrally, Regulus is white and it's companion is yellow.&nbsp; In my C5 the companion has a decidedly&nbsp;bluish cast, while Regulus is a dazzlingly brilliant white.</span><br /><br /><span style="color: #38761d;"><u>54 Leonis</u></span><span style="color: black;">&nbsp;&nbsp; Magnitude 4.5-6.3 Sep 6.5".&nbsp; Another close double for smaller scopes, 54 Leonis takes a liitle more effort to locate but it's worth it.&nbsp; A Star Chart or Observers Guide&nbsp;will help you here.&nbsp; 54 Leonis is a nice double with contrasting colors of white and blue.&nbsp; My 80mm will do the job at 100x.&nbsp; In my 8" LX200 at 200x the color contrast is much more noticable.&nbsp; Quite a beautiful pair.</span><br /><br /><span style="color: #38761d;"><u>Alpha CVn</u></span><span style="color: black;">&nbsp;&nbsp; Magnitude 2.5-5.9 Sep 19".&nbsp; Also known as Cor Caroli, this star is located in the center of the V-shaped constellation fo Canes Venatici.&nbsp; Look south&nbsp;of the Big Dipper's handle.&nbsp; A V-shaped asterism lies at a right angle to the end of the Dipper's handle, underneath the handle.&nbsp; Alpha CVn is the bright star in the center.&nbsp; This is a pretty double in small scopes, and a fine target following Alcor &amp; Mizar.&nbsp; Both stars appear white, with&nbsp;a yellow/blue tinge to the secondary,&nbsp;in my 80mm refractor.</span><br /><br /><span style="color: #38761d;"><u>Delta Corvi</u></span><span style="color: black;">&nbsp;&nbsp; Magnitude 3.0-9.2 Sep 24".&nbsp; The constellation of Corvus is an easily recognizable parallelogram southwest of the star&nbsp;Spica in Virgo,&nbsp; well to the south of Leo.&nbsp; Delta, or 7 Corvi, is a visual double with Eta Corvi in the northeast corner of the asterism.&nbsp; Delta itself is a telescopic double.&nbsp; I like to use 100x in my C5 or 8" LX200 to bring out the fainter companion better.&nbsp; My 80mm will show the double easily enough, but it isn't quite as attractive in a smaller scope.&nbsp; The primary is a sparkling white, and the secondary a much fainter blue color.&nbsp; Very pretty.</span><br /><br /><span style="color: #38761d;"><u>Struve 1669</u></span><span style="color: black;">&nbsp;&nbsp; Magnitude 6.0-6.1 Sep 5.4.&nbsp; Struve 1669 is composed of two equally bright yellowish stars.&nbsp; It is located about a third of the way to Spica, a little north of the line.&nbsp; A&nbsp;finderscope and star chart will&nbsp;help you locate it.&nbsp; 75-100x&nbsp;will do nicely on this tighter mtched pair.&nbsp; It is pretty in my C5, one star appears to have a&nbsp;slightly&nbsp;deeper color.&nbsp; In my Cave Astrola 10" reflector the color difference is a little easier to detect, but the stars are still&nbsp;close to&nbsp;equal.</span><br /><br />Of course, this list is by no means complete!&nbsp; A <a href="http://www.amazon.com/Cambridge-Star-Atlas-Wil-Tirion/dp/0521173639/ref=tmm_other_title_0?ie=UTF8&amp;qid=1302286336&amp;sr=1-1">star chart</a>, a good <a href="http://users.compaqnet.be/doublestars/">listing of Double Stars</a>, and a decent telescope can entertain you with pleasing views for a lifetime.&nbsp; I never get tired of obseving Double Stars, and I frequently revisit my favorites while hunting down some I haven't seen before.&nbsp; A bright moon can always be observed, but double stars are a great option when the moon washes out the fainter objects.<br /><br />Happy observing!DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com2tag:blogger.com,1999:blog-7808051055748780951.post-81952564824217782962011-04-02T09:49:00.004-05:002012-01-18T14:48:16.665-06:00Saturn: The Showpiece of Spring <br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-tW25zVez4xA/TZco2a2fMMI/AAAAAAAAAMc/CLyvnYzd6_E/s1600/Saturn+Paul+Haese.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" r6="true" src="http://1.bp.blogspot.com/-tW25zVez4xA/TZco2a2fMMI/AAAAAAAAAMc/CLyvnYzd6_E/s400/Saturn+Paul+Haese.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(Courtesy: <a href="http://paulhaese.net/Saturn29March20111316UT.html">Paul Haese</a>)<br />Link to Website: <a href="http://paulhaese.net/">http://paulhaese.net/</a>/</td></tr></tbody></table>  <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">I think it is safe to say that Saturn viewed through a telescope has&nbsp;"wowed" more people than any other object.&nbsp; Even a very small telescope of mediocre quality&nbsp;can do the job.&nbsp; A decent medium sized telescope will amaze you.&nbsp; A quality larger scope will provide literally&nbsp;jaw dropping views...</div><a name='more'></a><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />Astronomy DJ&nbsp;takes a closer&nbsp;look at the 6th planet from&nbsp;our sun,&nbsp;Saturn.&nbsp; Saturn is&nbsp;the second gas giant beyond the asteroid belt.&nbsp; Orbiting our sun at a distance 9 times as far as earth,&nbsp;Saturn completes one orbit every 29 1/2 years.&nbsp; </div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">On April 3rd Saturn will be at opposition (closest to earth), the date when a planet outside of earths orbit is directly opposite earth from the sun.&nbsp; In other words, the earth is directly between the sun and Saturn, and Saturn is well positioned for viewing&nbsp;for a&nbsp;month or two before and after. </div></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-FohXoxpMQcQ/TZY4Lbv6_wI/AAAAAAAAAMU/12Ahrj9_2iw/s1600/2000px-Positional_astronomy_svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="279" r6="true" src="http://4.bp.blogspot.com/-FohXoxpMQcQ/TZY4Lbv6_wI/AAAAAAAAAMU/12Ahrj9_2iw/s320/2000px-Positional_astronomy_svg.png" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a href="http://en.wikipedia.org/wiki/File:Positional_astronomy.svg">credit</a></div></td></tr></tbody></table><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">My first view of Saturn is forever etched in my memory.&nbsp; My dad bought my first telescope for my 11th birthday.&nbsp; It was a 3" reflector from Edmund Scientific.&nbsp; It had a white cardboard tube, a poor alt/az mount, a completely useless finder scope, and .965 eyepieces of 30x, 60x, and 120x.&nbsp; With patience you could center an object and focus it.&nbsp; It actually gave pretty sharp views in spite of it's other shortfalls.&nbsp; I spent about an hour looking at every star in the section of sky it was suppose to be in, except for one that I knew was too bright to be Saturn.&nbsp; I was a novice, remember.&nbsp; I couldn't find it and was extremely discouraged.&nbsp; I decided to pack it in for the night, but decided I might as well have a look at that really bright star I had been skipping all night&nbsp;before I went in.&nbsp; I focused at 30x...and nearly fell over with surprise!&nbsp; I was jumping around&nbsp;and yelling like I'd won the lottery or something.&nbsp; I'll never forget the feeling, or the sight.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Saturn is always interesting to look at with any size telescope.&nbsp; A good 5-8" telescope will give really nice views.&nbsp; Steady seeing is important, but fleeting moments of good seeing will reward you if you are patient at the eyepiece.&nbsp; The rings around Saturn are made of ice chunks that range in size from dust, to a half mile diameter.&nbsp; The main division in the rings is called the Cassini division, and is easily&nbsp;visible in 5" or even smaller scopes with steady skies.&nbsp; Subtle detail in the rings themselves&nbsp;is visible in larger instruments.&nbsp; The angle of the rings varies over&nbsp;a 14 year period&nbsp;from edge on to a maximum tilt of about 27 degrees seen from earth.<br /><div class="separator" style="clear: both; text-align: center;"><br /></div> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-6toCjcDVMTc/TZdZ7BmIUpI/AAAAAAAAAMg/IOoU8u-g9AU/s1600/691px-Saturn%252C_Earth_size_comparison.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="277" r6="true" src="http://1.bp.blogspot.com/-6toCjcDVMTc/TZdZ7BmIUpI/AAAAAAAAAMg/IOoU8u-g9AU/s320/691px-Saturn%252C_Earth_size_comparison.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">A size comparison of Saturn with earth,<br />Saturn's rings are&nbsp;about 150,000 miles across!<br />(<a href="http://en.wikipedia.org/wiki/File:Saturn,_Earth_size_comparison.jpg">image source</a>)</td></tr></tbody></table> </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Many of Saturn's moons are visible in small to medium telescopes as well, including Titan,&nbsp;the only&nbsp;satellite in the solar system with an atmosphere.&nbsp; Half again the size of our moon, Titan&nbsp;has been found to have a largely nitrogen atmosphere, with surface liquid, likely liquid methane.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Take advantage of the opportunity the next couple of months will provide and take a look at Saturn up close and in person.&nbsp; It is easy to find a few degrees above Spica in the contellation of Virgo&nbsp;in the southeast sky a few hours after sunset.&nbsp; In a month or two it will be higher in the south at the same time.&nbsp;</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Thanks for reading!</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"></div> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-20046058853075484962011-03-25T12:33:00.001-05:002011-10-13T15:24:15.455-05:00Open Clusters of Spring<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://lh3.googleusercontent.com/-8fvGORkLPX8/TYy77_ELfiI/AAAAAAAAAMA/AIxC4VcFqR0/s1600/Messier-35-and-NGC-2158.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="214" r6="true" src="https://lh3.googleusercontent.com/-8fvGORkLPX8/TYy77_ELfiI/AAAAAAAAAMA/AIxC4VcFqR0/s320/Messier-35-and-NGC-2158.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M35 and NGC2158 in the Constellation Gemini<br />(<a href="http://commons.wikimedia.org/wiki/File:Messier-35-and-NGC-2158.jpeg">image source</a>)</td></tr></tbody></table>Open clusters of stars are a great target for small and <a href="http://www.astronomydj.com/p/big-telescopes-what-to-buy.html">large telescopes</a> alike.&nbsp; Our Universe Today zeroes in on a few favorites in this article.&nbsp; Late winter and early spring provide many opportunities for pleasurable study...<br /><br /><a name='more'></a><br />Auriga and Gemini are great constellations for open clusters.&nbsp; Both constellations are well placed for viewing right now, shortly after sunset.&nbsp; <br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://lh6.googleusercontent.com/-AkJ0ygd9ayo/TYy-_MaVglI/AAAAAAAAAME/noHHwKvUcfE/s1600/320px-Auriga_constellation_map_svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" r6="true" src="https://lh6.googleusercontent.com/-AkJ0ygd9ayo/TYy-_MaVglI/AAAAAAAAAME/noHHwKvUcfE/s1600/320px-Auriga_constellation_map_svg.png" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://commons.wikimedia.org/wiki/File:Auriga_constellation_map.svg">image source</a>)</td></tr></tbody></table>M36, 37, and 38 are all&nbsp;easy to find open clusters.&nbsp; A pair of decent <a href="http://www.astronomydj.com/p/binoculars-for-astronomy.html">binoculars</a>&nbsp;is all you need to find them from suburban skies.&nbsp; If you are fortunate enough to live somewhere remote and dark, you can see them with the unaided eye quite readily.&nbsp;&nbsp;A good small telescope brings them to life.<br /><br />M36 is a fine open cluster with&nbsp;between 30 and 40 stars ranging from 9th-13th magnitude.&nbsp; It lies at a distance of a little over 4000 light years.&nbsp; M36 is a little over half the size telescopically of M37 and M38.<br /><br />M&nbsp;38 is a&nbsp;richer cluster than M36.&nbsp; It's brightest member is&nbsp;magnitude 8.&nbsp; About 70&nbsp;stars from magnitude 9-12 are visible in small scopes.&nbsp; It has several double stars, and chains of stars with starless lanes in between.<br /><br />M37&nbsp; is the best of Auriga's open clusters.&nbsp; Over 150 stars from 9th-12th magnitude can be seen in an area about the same size as M38.&nbsp; M37 is more compressed with a higher concentration of stars toward the middle, one star being noticeably brighter.&nbsp; It reminds many of M11 in the constellation Scutum.<br /><br /> Gemini is a treasure trove of decent fainter clusters to explore, but without doubt, M35 is it's best open cluster.&nbsp; Lying just below Auriga's "big three" on the map above, M35 is a convenient hop away for your telescope.&nbsp; Lying over 2000 light years distant, M35 has 70 or so stars visible in an area a little larger than M37, about a&nbsp;1/2 of a degree field.&nbsp; More than 20&nbsp;of these range in magnitude between 7.5 and 10, making the cluster appear much richer.&nbsp; In the photograph at the beginning of this article you will notice the fainter, smaller&nbsp;cluster just to the lower right.&nbsp; This is NGC2158.&nbsp; Below is a close up shot taken with the dedicated 2.5-meter telescope at Apache Point Observatory, New Mexico.&nbsp; Check out the difference in the two pictures!<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://lh6.googleusercontent.com/-Nbl4otjPP9k/TYzO4f6A4NI/AAAAAAAAAMI/x3JopXvphDs/s1600/ngc2158+sdss.org.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="259" r6="true" src="https://lh6.googleusercontent.com/-Nbl4otjPP9k/TYzO4f6A4NI/AAAAAAAAAMI/x3JopXvphDs/s320/ngc2158+sdss.org.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">NGC 2158 courtesy of the Sloan Digital Sky Survey<br />(<a href="http://www.sdss.org/">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">At a distance of 13,000 light years, NGC2158 is one of the most distant open clusters that can be seen in amatuer telescopes.&nbsp; You'll need a little bigger scope to see it.&nbsp;&nbsp;An 8" scope will reveal it as a hazy patch with several individual stars&nbsp;from a dark location.&nbsp; In larger scopes it looks kind of like a loose globular cluster.&nbsp; If NGC2158 were at the same distance as M35 it would be one of the best open clusters in the entire sky.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">I hope you enjoyed my latest entry, and that you get a chance to go out and observe these wondrous open clusters firsthand, in Our Universe Today!</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-88017363156428330602010-12-02T00:00:00.005-06:002011-10-13T15:48:17.444-05:00The Orion Nebula (M42) <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TPcp8UtIVlI/AAAAAAAAALk/wwF_IzblHKA/s1600/Messier-42-10_12_2004-filtered.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="275" ox="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TPcp8UtIVlI/AAAAAAAAALk/wwF_IzblHKA/s400/Messier-42-10_12_2004-filtered.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M42 The Great Nebula in Orion\<br />(<a href="http://commons.wikimedia.org/wiki/File:Messier-42-10.12.2004-filtered.jpeg">image source</a>)</td></tr></tbody></table> The Constellation of Orion&nbsp;is a favorite among <a href="http://www.astronomydj.com/p/choosing-telescope.html">telescope</a> enthusiasts.&nbsp; The cold, crisp nights of winter offer a rich tapestry of astronomical objects for viewing, and the Great Nebula in Orion takes center stage.&nbsp; Also commonly referred to as M42, the Orion Nebula offers tremendous opportunities for telescopes of all sizes.&nbsp; Let's start off with a little about the Orion Constellation and where it's located...<br /><br /><a name='more'></a><br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TPcrgjR35oI/AAAAAAAAALo/hq_LjLVJe7M/s1600/Uranometria_orion.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" ox="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TPcrgjR35oI/AAAAAAAAALo/hq_LjLVJe7M/s320/Uranometria_orion.jpg" width="230" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Bayer's 1661 copperplate engraving<br />of the Orion constellation<br />(<a href="http://commons.wikimedia.org/wiki/File:Uranometria_orion.jpg">image source</a>)</td></tr></tbody></table> <span style="color: #38761d;"><u>The Constellation of Orion</u></span><span style="color: #38761d;">:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span><br /><br /><span style="color: black;">Composed of many bright stars, Orion the Hunter&nbsp;is an easily recognizable pattern of stars to find.&nbsp; If you are looking for a big guy with a club, as depicted to the right, you will have to use a lot of imagination!&nbsp; It is nice to know information though, as you will commonly hear spoken reference to "Orion's shoulder, head, knee, foot, and club".&nbsp; Knowing which stars these are associated with certainly&nbsp;doesn't hurt.&nbsp; </span><br /><br /><span style="color: black;">"Connecting the dots" in a more modern fashion renders a more&nbsp;easily located pattern that is of more practical use.&nbsp; Below is an example of the constellation outline you will see with some charting software.&nbsp; You can download excellent charting software for free at a couple of locations.&nbsp; Here are two I like:</span><br /><a href="http://www.hnsky.org/software.htm">HNSKY</a> &amp; <a href="http://www.ap-i.net/skychart/start">Cartes du Ciel</a>.&nbsp; Try them out.&nbsp; There is a bit of&nbsp;a learning curve for each, but nothing major, and they are amazing tools once you get used to them.<br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/_nlLwlwEXLHU/TPctXD6wHHI/AAAAAAAAALs/MlBcT40fSYw/s1600/Orion_constellation_map.png" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" ox="true" src="http://4.bp.blogspot.com/_nlLwlwEXLHU/TPctXD6wHHI/AAAAAAAAALs/MlBcT40fSYw/s320/Orion_constellation_map.png" width="310" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">A simple chart of the&nbsp;Orion constellation<br />(<a href="http://commons.wikimedia.org/wiki/File:Orion_constellation_map.png">image source</a>)</td></tr></tbody></table> &nbsp; <br /><u><span style="color: #38761d;">Where to Look:</span></u><br /><br />In December, look for Orion low in the east&nbsp;an hour after sunset.&nbsp; An hour or two&nbsp;before midnight,&nbsp;the constellation&nbsp;has risen to a point high in the southeast sky, well placed for viewing.&nbsp; Later in December, and into January, Orion attains this position even&nbsp;earlier in the evening.&nbsp; It will be well placed for the next&nbsp;several months.<br /><br /><br /><br /><u><span style="color: #38761d;">The Orion Nebula, M42:</span></u><br /><br /><span style="color: black;">Without question, the most popular object in the constellation of Orion is the Orion Nebula.&nbsp; The surrounding&nbsp;constellations of Taurus, Monoceros, and Auriga all&nbsp;have numerous fine targets for telescopes large and small, but&nbsp;the Orion Nebula is where I usually wind up spending the most time.</span><br /><br /><span style="color: black;">As mentioned, it is often referred to as M42.&nbsp; This is a&nbsp;reference to a catalog of&nbsp;objects compiled by French astronomer&nbsp;Charles Messier in&nbsp;the 1770's.&nbsp; Charles was a comet hunter who used a refractor telescope of around 4 inches of aperture.&nbsp; He began&nbsp;keeping a&nbsp;log of comet like objects to avoid wasting time finding the same object again and again.&nbsp; This log became the now famous Messier List, used by many today&nbsp;as a guide to some of the best objects for small telescopes.&nbsp; The list has grown to 110 objects which Messier and his assistant observed.&nbsp; M42 is one of them.&nbsp; The list is a good place to start for new owners of small to medium telescopes.&nbsp; The <a href="http://www.rasc.ca/messier/index.shtml">Royal Astronomical Society of Canada</a> offers several certificate programs, including one on the Messier objects, that will help you to learn your way around the sky if you are just starting out.</span><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TPcvGEd7wsI/AAAAAAAAALw/X1Lc_MaSnwQ/s1600/Orion_Nebula_M42_Trapezium_Cluster_VIS-IR_HST.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" ox="true" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TPcvGEd7wsI/AAAAAAAAALw/X1Lc_MaSnwQ/s400/Orion_Nebula_M42_Trapezium_Cluster_VIS-IR_HST.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://commons.wikimedia.org/wiki/File:Orion.Nebula.M42.Trapezium.Cluster.VIS-IR.HST.jpg">image source</a>)</td></tr></tbody></table> The Orion Nebula is more than just a nebula.&nbsp; It is a birthplace of stars.&nbsp; At it's core lies a multiple star system commonly called the Trapezium (Theta Orionis),&nbsp;after it's trapezoidal shape.&nbsp; With a 3 inch scope, all four stars are easily&nbsp;visible.&nbsp; In larger instruments more stars are visible surrounding the Trapezium, and&nbsp;one&nbsp;is visible within it,&nbsp;if the telescope is large enough.&nbsp;&nbsp;Much of the intricate detail of the Orion Nebula is&nbsp;visible in a telescope of 6-10 inches.&nbsp; In some ways, the eye can see more than the camera as the center region is usually&nbsp;washed out on long exposures.<br /><br /><u><span style="color: #274e13;">What Exactly is M42?&nbsp; A Short Primer:</span></u><br /><br />The more you learn about this region of space, the more interesting it is to observe!&nbsp; I highly recommend this&nbsp;<a href="http://hubblesite.org/gallery/tours/tour-orion/">image tour</a>&nbsp;from the&nbsp;Hubble&nbsp;site&nbsp;as a basic primer on the Orion Nebula.&nbsp; It is very well done and will&nbsp;help put the many observable features into perspective.&nbsp; Keep in mind, you won't see it like this from your backyard, it is&nbsp;the Hubble ST after all.&nbsp; <br /><br />You may,&nbsp;however,&nbsp;be surprised at what you can see with your own equipment.&nbsp; For instance, the Orion&nbsp;nebula is&nbsp;impressive even&nbsp;in <a href="http://www.astronomydj.com/p/binoculars-for-astronomy.html">10x50 binoculars</a>.&nbsp; From a dark location it is beautiful in binoculars.&nbsp; More and more detail becomes visible as the aperture increases.&nbsp; Light pollution filters help with contrast and detail as well.&nbsp; The pink and purple colors aren't visible without time exposure photography, or a really large telescope, so do not expect to see&nbsp;that.&nbsp; The nebula has a greenish cast to it through the eyepiece of common telescopes.<br /><br /><u><span style="color: #38761d;">Variable Stars:</span></u><br /><br /><span style="color: black;">There are over 50 identified&nbsp;variable stars within the nebula, a dozen of which are easily within reach of smaller telescopes.&nbsp; Most show erratic and rapid variation, typically in a magnitude range of 1-1.5 variance.&nbsp; You can learn more about variable stars at the <a href="http://www.aavso.org/">AAVSO</a> website.&nbsp; You can create and print your own variable star&nbsp;charts from this site, also.</span><br /><br />The next clear night you get, go outside and have a look for yourself at one of the finest showpieces of Our Universe Today.<br /><br />Thanks,<br />DJ<br />&nbsp;&nbsp; <br /><br />&nbsp;&nbsp; <br /><br /><span style="color: black;">&nbsp;&nbsp;&nbsp;</span>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-85775382853930579062010-11-19T09:31:00.001-06:002011-10-13T15:48:58.231-05:00Astronomy DJ newsflash: Comet Hartley 2: Snowstorm!<div> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/_nlLwlwEXLHU/TOaVX3A0AEI/AAAAAAAAALc/DsGTiUkiYsI/s1600/snowstormhartley2.jpg" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5541280628662861890" src="http://4.bp.blogspot.com/_nlLwlwEXLHU/TOaVX3A0AEI/AAAAAAAAALc/DsGTiUkiYsI/s400/snowstormhartley2.jpg" style="display: block; height: 214px; margin: 0px auto 10px; text-align: center; width: 400px;" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Enhanced image of Nov4 flyby of&nbsp;Hartley 2 <br />(<a href="http://science.nasa.gov/science-news/science-at-nasa/2010/18nov_cometsnowstorm/">image source</a>)</td></tr></tbody></table> <br /><div>Comet Hartley 2 is providing some surprises. Namely, a snowstorm! Check out this<a href="http://science.nasa.gov/science-news/science-at-nasa/2010/18nov_cometsnowstorm/"> link</a> to a Nasa News Brief.&nbsp; The article is very interesting. It compares this cometary flyby with previous encounters with Halley, Borrelly, Wild 2, and Temple 1.&nbsp; The same space craft (Deep Impact) made both the Hartley 2 and Temple 1 flybys, indicating an actual difference in activity, not just a difference in camera resolution.&nbsp; <br /><br />I hope you enjoy the view!<br /><br />DJ</div><br /><br /><div></div><br /><br /><div></div></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-5898544679918619482010-11-08T14:47:00.000-06:002011-10-13T15:47:48.755-05:00November Skies <br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/_nlLwlwEXLHU/TNbau4Nh-2I/AAAAAAAAAK4/nz5O0XnRAk8/s1600/m31_xray_opt_pullout%5B1%5D.JPG" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="308" px="true" src="http://2.bp.blogspot.com/_nlLwlwEXLHU/TNbau4Nh-2I/AAAAAAAAAK4/nz5O0XnRAk8/s400/m31_xray_opt_pullout%5B1%5D.JPG" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Optical &amp; Chandra X-ray Image of Andromeda Galaxy <br />(<a href="http://nasaimages.org/">image credit</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">November skies have many offer many fine targets for back yard observing of our universe.&nbsp; Check out the monthly sky guide tab for a video with more about what's up in November.&nbsp; The video barely scratches the surface, though.&nbsp; Here are a few of my favorites under November skies...</div><br /><a name='more'></a><br /><br /><br /><u><span style="color: #38761d;">Galaxies:</span></u><br /><br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TNbYLcQLQSI/AAAAAAAAAK0/aYvk-DENROk/s1600/M31.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="238" px="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TNbYLcQLQSI/AAAAAAAAAK0/aYvk-DENROk/s320/M31.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M31 the Andromeda Galaxy as seen through<br />&nbsp;binoculars from a dark location<br />(<a href="http://commons.wikimedia.org/wiki/File:M31.jpg">image source</a>)</td></tr></tbody></table>The Andromeda Galaxy is a fine object to start with.&nbsp; Because of it's size,&nbsp;it is best viewed with low powers from a dark location.&nbsp; Good binoculars or an 80mm f/5 telescope will give nice views, even from suburban locations.&nbsp; The rule of thumb with any galaxy is, the darker the location, the better the view.&nbsp; <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">This galaxy covers well&nbsp;over two degrees of sky, so a smaller, wide field instrument is needed to see all of it at once.&nbsp; Larger telescopes will give more detailed views of the central portion, and it's two nearby companion galaxies.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><u><span style="color: #38761d;">Variable Stars:</span></u></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">There are always many variable stars that are interesting to monitor.&nbsp; Two of my favorites are Algol, and Herschel's "Garnet Star".</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Algol, also known as Beta Persei,&nbsp;is an eclipsing binary system that varies in brightness from magnitude 2.1 down to 3.4 every 2.867 days.&nbsp; The drop in brightness to minimum, and the return to magnitude 2.1 all takes place over just a few hours, making it possible to view the entire process in one long night of&nbsp;observing.<br /><br />For more about viewing Algol, try this <a href="http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algol.html">link</a>.<br /><br />Herschel's "Garnet Star" aquired this moniker from Sir William Herschel, who described it as&nbsp;having "a very fine deep garnet colour".&nbsp; Also known as Mu Cephei, the star varies in brightness from a relatively bright magnitude 3.6 down to 5th magnitude, much fainter yet still visible to the unaided eye from&nbsp;most backyards.<br /><br />Mu Cephei is one of my favorite stars not so much because of it's&nbsp;variablity, but because of it's fine color and the facts about the star.&nbsp; Mu Cephei is one of the 5 or 6 most massive stars known.&nbsp;&nbsp;It's estimated distance of about 1,500 light years makes it look a lot fainter than it really is.&nbsp; This star has a diameter of about 15 astronomical units, one A.U. being the mean distance from the earth to the sun.&nbsp; If this was our sun, it would extend beyond the orbit of Jupiter!<br /><br />Check it out with binoculars and see how red you think this star is.&nbsp; I think it looks ruby red in 10x50's, while in an 8" SCT it looks bright orange with yellow tints.<br /><br />Here is a link to a <a href="http://en.wikipedia.org/wiki/Cepheus_(constellation)">wiki</a> about the constellation Cepheus that has a chart.&nbsp; Mu Cephei is the star just above I.C. 1396&nbsp;towards the bottom of the chart.<br /><br /><u><span style="color: #38761d;">Star Clusters:</span></u><br /><br />So many star clusters, so little time.&nbsp; That's how I feel on a clear night with a telescope once I get started cluster hopping.&nbsp; I truly enjoy observing star clusters with my 8" SCT.&nbsp; Many of the brighter clusters look great, or even best in a smaller, wider field scope.&nbsp; The 8", however,&nbsp;really opens the door to a wide vista of lesser known objects, some of which are beautiful.<br /><br />For some clusters and asterisms, a small telescope or even binoculars are hard to beat.&nbsp; Some fine examples are M45, the Pleiades; NGC 869 &amp; 884, the Double Cluster; the Haydes Cluster in Taurus; and Collinder 399, the Coathager in Vulpecula.&nbsp; These are all visible in November.<br /><br />A larger scope of 4-8 inches will showcase some less frequented star clusters which can hold their own with some of these apparently larger, more popular targets.&nbsp; Among these are NGC 457 and 663 in Cassiopea; NGC 6910 in Cygnus; NGC 7160 and I.C. 1396 in Cepheus.&nbsp; These are just a few of the interesting objects I enjoy in November.<br /><br /><u><span style="color: #38761d;">The Moon &amp; Planets this month:</span></u><br /><br /><span style="color: black;">Of course, Jupiter is still a fantastic sight all of November.&nbsp; Venus is easily visible as a huge crescent shape just before sunrise, even in 10x50 binoculars.&nbsp; Last but not least, our moon cycles through the sky each and every month, offering different targets each night as the phase changes.&nbsp; Here's a link to a fun and informative site about the moon.&nbsp; <a href="http://inconstantmoon.com/">Check it out</a>.</span><br /><br />Thanks for dropping in,<br /><br />Dale</div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com35tag:blogger.com,1999:blog-7808051055748780951.post-5001690193699088152010-11-04T14:27:00.000-05:002011-10-13T15:47:20.238-05:00Astronomy DJ newsflash: Comet Hartley2 <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/_nlLwlwEXLHU/TNMD44CdJLI/AAAAAAAAAKw/Qf6gykQW_So/s1600/comet+hartley2+flyby.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="280" px="true" src="http://4.bp.blogspot.com/_nlLwlwEXLHU/TNMD44CdJLI/AAAAAAAAAKw/Qf6gykQW_So/s400/comet+hartley2+flyby.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Comet Hartley2 (<a href="http://epoxi.umd.edu/">image credit</a>)<br />One of the Epoxi mission recently returned photos of the close approach</td></tr></tbody></table> Nasa has successfully completed a flyby of Comet Hartley2, returning never before seen image close ups of the comet nucleus.&nbsp; You can view all the images at <a href="http://epoxi.umd.edu/">this link</a>.&nbsp; Be patient, the server is kind of busy right now!<br /><br /><br />Excerpt taken from <a href="http://www.jpl.nasa.gov/news/news.cfm?release=2010-371">http://www.jpl.nasa.gov/news/news.cfm?release=2010-371</a><br /><br /><span style="color: blue;">NASA Mission Successfully Flies by Comet Hartley 2<br />Jet Propulsion Laboratory<br />November 04, 2010<br /><br />PASADENA, CALIF. - NASA's EPOXI mission successfully flew by comet<br />Hartley 2 at about 7 a.m. PDT (10 a.m. EDT) today, and the spacecraft<br />has begun returning images. Hartley 2 is the fifth comet nucleus visited<br />by a spacecraft.<br /><br />Scientists and mission controllers are currently viewing<br />never-before-seen images of Hartley 2 appearing on their computer<br />terminal screens.</span><br /><br /><span style="color: blue;">EPOXI is an extended mission that utilizes the already "in-flight" Deep<br />Impact spacecraft to explore distinct celestial targets of opportunity.<br />The name EPOXI itself is a combination of the names for the two extended<br />mission components: the extrasolar planet observations, called<br />Extrasolar Planet Observations and Characterization (EPOCh), and the<br />flyby of comet Hartley 2, called the Deep Impact Extended Investigation<br />(DIXI). The spacecraft has retained the name "Deep Impact."</span><br /><br /><br />Comet Hartley2 has been the focus of comet watchers in recent months.&nbsp; Visible in binoculars and small telescopes, it has rekindled the interest of many involved with astronomy as a hobby or pastime.&nbsp; A pretty dark site was needed to get more than a glimpse of the comet.<br /><br />It appeared as a large, faint, ghost-like object in my 80mm refractor from a suburban location, barely visible against the grayish background sky.&nbsp; From a much darker location with the same scope, it was much easier to observe, appearing much brighter.&nbsp; It had a greenish translucence from the darker site, and looked a little brighter toward the center.&nbsp; I was never able to see a tail visually, though others reportedly were.&nbsp; A short tail was visible in time exposure photos.<br /><br />Thanks for stopping by,<br />DaleDJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-56267480534219146892010-10-17T22:30:00.001-05:002011-10-13T15:46:52.093-05:00Astronomy DJ highlights: The Moon & JupiterDon't let a bright moon keep you indoors, with your telescope in a closet...there&nbsp;are plenty of great things&nbsp;you can look at and do.&nbsp; <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/_nlLwlwEXLHU/TLu16QWg3QI/AAAAAAAAAKc/UdGCK1WQK2g/s1600/moonjupe14oct10+034.JPG" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="240" src="http://2.bp.blogspot.com/_nlLwlwEXLHU/TLu16QWg3QI/AAAAAAAAAKc/UdGCK1WQK2g/s320/moonjupe14oct10+034.JPG" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">1st Quarter Moon<br />(taken w/&nbsp;8" Schmidt Cassegrain &amp;&nbsp;Nikon Coolpix) </td></tr></tbody></table><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Jupiter is still fantastic right now.&nbsp;&nbsp;It's four bright moons provide a nightly dance for entertainment as they orbit the planet.&nbsp; The cloud bands are visible in&nbsp;even very <a href="http://www.astronomydj.com/p/choosing-telescope.html">small telescopes</a>, and every 10 hours the&nbsp;Great Red Spot takes center stage in medium&nbsp;and larger scopes.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Double stars are a great target on moonlit nights.&nbsp; There are always plenty&nbsp;to choose from.&nbsp;&nbsp;Many are very easy to split with a small scope, and have pretty, contrasting colors.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div>And,&nbsp;of course, you can spend some very relaxing hours with earth's nearest solar system neighbor, the moon...<br /><a name='more'></a><br /><u><span style="color: #38761d;">Let's start with double stars.&nbsp; Doubles, and multiple stars have two basic categories</span></u>:&nbsp; <br /><br /> 1. Stars that appear to be very close to each other because of our line of sight through the galaxy, but are actually not at all near each other.&nbsp; If earth was in a different part of the galaxy and our perspective were changed, these stars would not appear as close multiple stars.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TLu3T1A8MiI/AAAAAAAAAKg/xhz8KZN2pXI/s1600/661px-Albireo_a.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="361" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TLu3T1A8MiI/AAAAAAAAAKg/xhz8KZN2pXI/s400/661px-Albireo_a.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Beautiful Albireo (Beta Cygni)<br />(<a href="http://commons.wikimedia.org/wiki/File:Albireo_a.jpg">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">2. True binary and multiple systems that orbit around each other.&nbsp; There are surprisingly many of these systems.&nbsp; There are all kinds and sizes of stars with different colors, temperatures, distances between each other, and orbital periods.&nbsp; </div><br />There are many online "best of the best" lists available.&nbsp; There are books as well.&nbsp; My favorite book/s for double star information to plan a viewing session is <a href="http://www.amazon.com/s/ref=nb_sb_ss_c_1_28?url=search-alias%3Dstripbooks&amp;field-keywords=burnham%27s+celestial+handbook&amp;sprefix=burnham%27s+celestial+handbook">Burnham's Celestial Handbook</a>.&nbsp; There are books with more complete listings, but Burnham's is a classic.&nbsp; No library is complete with this three volume set.<br /><br />For an online planning tool for double and multiple stars, try this link of <a href="http://users.compaqnet.be/doublestars/">Top 200 Double Stars</a>.&nbsp;&nbsp; A very nice collection with descriptions and ratings.&nbsp; It's cross referenced for easier planning.<br /><br /><span style="color: #38761d;"><u>Now, let's tackle an evening with Jupiter</u></span><span style="color: black;">:</span><br /><br />Easy to find, big, bright, beautiful, fascinatingly changing from hour to hour, what's not to like about Jupiter?&nbsp; You can even mess around with snapshots through your digital camera.&nbsp; I took this picture below with a handheld Nikon Coolpix last Thursday.&nbsp; It's not great by any stretch, but it took very little time, effort, and expense to get good enough results to be able to see cloud belts and the Great Red Spot.&nbsp; And it was fun!<br /><br /><div class="separator" style="clear: both; text-align: center;"></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/_nlLwlwEXLHU/TLu5wQ9ibkI/AAAAAAAAAKo/XhvBAhSpWlw/s1600/Copy+of+moonjupe14oct10+048.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="286" src="http://4.bp.blogspot.com/_nlLwlwEXLHU/TLu5wQ9ibkI/AAAAAAAAAKo/XhvBAhSpWlw/s320/Copy+of+moonjupe14oct10+048.JPG" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Jupiter taken w/ 8" Schmidt Cassegrain &amp; Nikon Coolpix</td></tr></tbody></table><br />To see what's up with Jupiter an any given night, go to the <a href="http://www.skyviewcafe.com/">Sky View Cafe</a>, set up the interactive planetarium, and click on the Moons/GRS tab.&nbsp; You can put the moons and planet into motion by advancing the time setting.&nbsp; It's cool to play with, and great for planning an evening out with the scope.<br /><br />Good optics and seeing conditions make all the difference when viewing planets.&nbsp; Invest in a nice <a href="http://www.astronomydj.com/p/telescope-eyepieces-5-things-you-want-3.html">planetary eyepiece</a> with a wide field of view, and a blue filter helps bring out the belts and red spot.&nbsp; A standard light pollution reduction filter (LPR) can&nbsp;also work well with Jupiter.<br /><br /><span style="color: #38761d;"><u>Last but not least, the Moon</u><span style="color: black;">:</span></span><br /><br /><span style="color: black;">I doesn't get any easier than this.&nbsp; But it's still very rewarding.&nbsp; Even taking decent pictures is easy.&nbsp; Just hold a digital camera (is there any other kind any more?) up to the eyepiece and plink away.&nbsp; You'll figure the rest out.&nbsp; Here's a nice shot of the 1st quarter moon I took recently with my 8" and Nikon Coolpix:</span><br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/_nlLwlwEXLHU/TLu8vk8VqAI/AAAAAAAAAKs/z042ZYvqjMo/s1600/moonjupe14oct10+036.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="300" src="http://2.bp.blogspot.com/_nlLwlwEXLHU/TLu8vk8VqAI/AAAAAAAAAKs/z042ZYvqjMo/s400/moonjupe14oct10+036.JPG" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">1st Quarter Moon</td></tr></tbody></table>You can play around with stuff like this for hours on a rainy night.&nbsp; A polarizing moon filter is nice to have.&nbsp; The moon is incredibly bright in a telescope.&nbsp; A good chart is fun to have when you look at your pictures.&nbsp; It is great for planning observing sessions too.&nbsp; <br /><br />The best area to observe is along the terminator (bottom of photo).&nbsp; You can see why.&nbsp; Long shadows bring out detail.&nbsp; The same area will look very different the next night, and a new area will be visible under the terminator each successive night.<br /><br />Well, I hope I have inspired you to get outside and have a long look at Our Universe.&nbsp; It's pretty cool stuff.<br /><br />Dale<br /><br /><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-60482951791901086312010-10-08T00:00:00.001-05:002011-10-13T15:17:49.905-05:00Dark skies <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TK6NAk658mI/AAAAAAAAAKI/ETSbfr6wDhY/s1600/MilkyWay_behind_Tree_2.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="200" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TK6NAk658mI/AAAAAAAAAKI/ETSbfr6wDhY/s200/MilkyWay_behind_Tree_2.jpg" width="133" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://upload.wikimedia.org/wikipedia/commons/2/2b/MilkyWay_behind_Tree_2.jpg">image source</a>)</td></tr></tbody></table> For the past two weeks I have been blessed with really clear skies.&nbsp; Two days in a row are fairly common around these parts.&nbsp; Two weeks is extraordinary.&nbsp;&nbsp;Clear skies are a stargazer's&nbsp;second best friend.&nbsp; Dark skies definitely&nbsp;rank number one, though.<br /><br />Unfortunately, I live in a fairly bright suburban area.&nbsp; I do&nbsp;have the good fortune to have&nbsp;a reasonably dark sky location within 30 minutes of my home. And as an added bonus, for the last four nights, I have been at a more remote location with skies dark enough to inspire...<br /><br /><div><a name='more'></a></div><br />You can certainly&nbsp;make do with a suburban viewing area.&nbsp; Many forms of astronomy aren't affected as much by somewhat brighter skies.&nbsp; Planetary viewing, variable star observing, lunar observing, and double stars all remain viable targets for the <a href="http://www.astronomydj.com/p/choosing-telescope.html">telescope</a> enthusiast who lives close to "the city".&nbsp; But, no matter what your specialty may be, a truly dark sky will knock your socks off.<br /><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TK6WOC9yT_I/AAAAAAAAAKM/GcI83AUi3yM/s1600/earth+at+night.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="230" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TK6WOC9yT_I/AAAAAAAAAKM/GcI83AUi3yM/s320/earth+at+night.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">(<a href="http://visibleearth.nasa.gov/view_rec.php?id=11793">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">I can't overstate the benefits of a dark sky location for astronomical viewing.&nbsp; All those faint fuzzies you can't see from the city are within reach of a decent telescope.&nbsp; Just standing under the skies with nothing but your eyes&nbsp;and looking up is&nbsp;awesome.&nbsp; A pair of <a href="http://www.astronomydj.com/p/binoculars-for-astronomy.html">binoculars</a> makes it&nbsp;doubly awesome.&nbsp; A small telescope with a wide field makes it incredible.&nbsp;&nbsp;A&nbsp;medium to large telescope, paired with some knowledge of the stars, makes for an inspiring night filled with oooh's and aaah's.&nbsp;&nbsp;I kid you not.</div><br />I have been to some really dark locations in my younger years.&nbsp; Back when my eyesight was very sharp.&nbsp; I have actually seen M81 with the unaided eye once, barely.&nbsp;&nbsp;For those of you who know, that's an impressively dark sky.<br /><br />I have been in a location once where there was an unobstructed horizon in every direction that was so dark, you could only tell where the horizon was because the stars ended there.&nbsp; To the west, you could watch them wink out as they sank below the horizon, and to the east they would pop into view as they rose above it.&nbsp; The winter milky way was visible from horizon to horizon as a distinct, bright band, brighter than most ever see the summer milky way.<br /><br />For the past four days I have been in a dark enough location to remind me&nbsp;of those times.&nbsp; Nowhere near&nbsp;as dark as those places, but very decent indeed.&nbsp; I had a good, low,&nbsp;southern horizon that reminded me of my observing area as a kid of eleven years of age.&nbsp; M6 and M7 were just above&nbsp;setting about an hour after sunset, yet&nbsp;both were easily visible to the eye.<br /><br />As I worked my way up through Sagittarius and Scutum with my 80mm rich field refractor, I was able to&nbsp;reacquaint myself with some old friends of the galaxy that are lost to the glare of lights at home.&nbsp; The Lagoon Nebula, the Triffid, M17, M22, M11, and many other fine objects in the lower southern sky.&nbsp; A good selection of <a href="http://www.astronomydj.com/p/telescope-eyepieces-5-things-you-want-3.html">eyepieces</a>, a good Barlow lens, and a nebula filter&nbsp;comes in handy.<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TK6gKXQx8dI/AAAAAAAAAKQ/QYa_8YihyEA/s1600/Pleiades-comet-Machholz.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="170" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TK6gKXQx8dI/AAAAAAAAAKQ/QYa_8YihyEA/s400/Pleiades-comet-Machholz.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M45 The Pleiades, and a comet<br />(<a href="http://upload.wikimedia.org/wikipedia/commons/3/37/Pleiades-comet-Machholz.jpeg">image source</a>)</td></tr></tbody></table> Later, the&nbsp;Pleiades rose in the east.&nbsp; Stunning under a dark sky in a&nbsp;four degree field of view.&nbsp; The double cluster in Perseus, and many more fine objects were visible.&nbsp; M31, the Andromeda Galaxy, is a true wide field gem under a dark sky.&nbsp; I have seen it with good binoculars&nbsp;years ago&nbsp;from a&nbsp;mountain top, and the&nbsp;experience is hard to describe.&nbsp; It still&nbsp;looked pretty decent where I was the last few nights, though.&nbsp; I wish my backyard looked as good!<br /><br /> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/_nlLwlwEXLHU/TK6ndCz1S9I/AAAAAAAAAKU/JukB63bzn1I/s1600/800px-Brian_-_Andromeda,_again__(by).jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" ex="true" height="237" src="http://2.bp.blogspot.com/_nlLwlwEXLHU/TK6ndCz1S9I/AAAAAAAAAKU/JukB63bzn1I/s400/800px-Brian_-_Andromeda,_again__(by).jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M31 the Andromeda Galaxy<br />(<a href="http://commons.wikimedia.org/wiki/File:Brian_-_Andromeda,_again._(by).jpg">image source</a>)</td></tr></tbody></table> Here's wishing you the dark skies of your dreams, and a telescope or binoculars to enjoy it with!<br /><br />Dale<br /><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-46973852864393363612010-09-30T16:16:00.002-05:002011-10-13T15:46:24.294-05:00Astronomy DJ on: Early Fall Skies<br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TKT86-oDhJI/AAAAAAAAAKA/6EfWkq7lNIQ/s1600/M57_c14.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="169" px="true" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TKT86-oDhJI/AAAAAAAAAKA/6EfWkq7lNIQ/s200/M57_c14.jpg" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">M57 The Ring Nebula<br />(<a href="http://commons.wikimedia.org/wiki/File:M57_c14.jpg">image source</a>)</td></tr></tbody></table><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Summer may be over, but you can still see some of the summer's best astronomical objects in the first two hours after sunset. With Cygnus high overhead at twilight, the skies are poised for a final glimpse of three fine targets for any telescope...</div><br /><br /><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">A quality telescope of three to eight inches in aperture will provide inspiring views of our universe. From the moon and planets to distant galaxies, and many sights in between, you are limited only by viewing conditions and your knowledge of the stars. Late September offers an abundance of objects from early evening into the morning hours. Today we will highlight three fine celestial beauties visible in the hours right after sunset.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TKT7K5mzwtI/AAAAAAAAAJ8/znTo5a9azcc/s1600/M13chart.JPG" imageanchor="1" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="240" px="true" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TKT7K5mzwtI/AAAAAAAAAJ8/znTo5a9azcc/s320/M13chart.JPG" width="320" /></a>The first and western most object is arguably the finest globular cluster in the northern hemisphere, M13, in the Constellation of Hercules. From a dark location, those with keen eyesight can just pick it up visually as a rather dim, fuzzy looking star. </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">In a three inch telescope at 50x you will see a fuzzy ball shaped object that gets brighter towards the center. It will exhibit a slightly mottled appearance, without being resolved into individual stars. A five inch scope at 125x will reveal hundreds of tiny outlying stars surrounding a brighter, unresolved central mass. An eight inch at 150x will show thousands of stars with much more of the central mass being resolved. A magnificent sight to behold.</div><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a href="http://2.bp.blogspot.com/_nlLwlwEXLHU/TKT6h89Pl7I/AAAAAAAAAJ4/wKXROefgSJw/s1600/M57chart.JPG" imageanchor="1" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="240" px="true" src="http://2.bp.blogspot.com/_nlLwlwEXLHU/TKT6h89Pl7I/AAAAAAAAAJ4/wKXROefgSJw/s320/M57chart.JPG" width="320" /></a>Next we venture eastward to Lyra. Not to far from it's brightest star, Vega, lies a tremendous planetary nebula, M57, which resembles a tiny smoke ring hovering among the stars. It is visible in binoculars from a fairly dark location. A three inch telescope at 50x shows a tiny ghostly ring, grayish in color against a dark background. A five inch at 100x will have similar brightness, but will be much larger in appearance with more detail visible. An eight inch at 200x gives an impressive view with better detail of it's structure. It also starts to take on a greenish hue. A splendid object at higher powers also. Light pollution filters, both broadband and narrow band (those specifically for planetary nebulae) work very well with M57, and the next object...</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TKT5WSEgh2I/AAAAAAAAAJw/COFChMVmIEI/s1600/M27chart.JPG" imageanchor="1" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="240" px="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TKT5WSEgh2I/AAAAAAAAAJw/COFChMVmIEI/s320/M27chart.JPG" width="320" /></a>M27, a large planetary nebula in the constellation Vulpecula. Use lower powers on this one. Filters like those mentioned above really bring out the best. Nicknamed the Dumbbell, it has a rectangular appearance, slightly narrower towards the center. It lies among many fine background stars, framing the field nicely in low powers of 50-75X. It has a distinct greenish cast to it from darker locations, even in smaller scopes. This one really gorgeous to gaze at.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">I hope you enjoyed the tour, and that you find the time to go out and see these fine views of our universe firsthand!</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Dale</div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-30815773330740924132010-09-24T17:48:00.005-05:002011-10-13T15:45:54.192-05:00Astronomy DJ vists: The Orion Constellation<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJyvWXM2PfI/AAAAAAAAAJU/P9jo5Z4yuFU/s1600/Orion_constellation.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="257" px="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJyvWXM2PfI/AAAAAAAAAJU/P9jo5Z4yuFU/s400/Orion_constellation.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Orion Constellation <br />(author: Matthew Spinelli)<br />(<a href="http://commons.wikimedia.org/wiki/File:Orion_constellation.jpg">image source</a>)</td></tr></tbody></table>Coming soon to your back yard, the fabulous Orion constellation of stars!&nbsp;&nbsp;&nbsp;Try staying up until 2am however, and you can enjoy them without the freezing weather.&nbsp; Those of us who have cold winters can relate.&nbsp; Orion also&nbsp;offers perhaps the&nbsp;most interesting nebula for small to medium sized telescopes, or even binoculars...<br /><a name='more'></a> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJyzIQK3MSI/AAAAAAAAAJg/2jVZI4IQd0Q/s1600/723px-Orion_constellation_Hevelius.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="165" px="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJyzIQK3MSI/AAAAAAAAAJg/2jVZI4IQd0Q/s200/723px-Orion_constellation_Hevelius.jpg" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Orion: The Hunter<br />(<a href="http://commons.wikimedia.org/wiki/File:Orion_constellation_Hevelius.jpg">image source</a>)</td></tr></tbody></table> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">You have to have a pretty lively imagination to see that guy with the shield and club, but Orion is still&nbsp;one of the most recognizable patterns of stars in the sky.&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Along with it's&nbsp;neighboring constellations of Taurus and Canis Major, Orion contributes many bright stars to our winter sky.&nbsp;&nbsp;The reason the winter sky seems to be so crisp and clear is this large concentration of bright stars.</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div>Here's a breakdown of some common terminology you'll hear when your are out under these stars with other observers. <br /><br /><u><span style="color: #38761d;">The Shoulder, Belt, and Sword of Orion:</span></u>&nbsp;&nbsp; <br /><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">  <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJ0pmXCg8MI/AAAAAAAAAJo/FSTGvWs5MEI/s1600/581px-Orion_constellation_map.png" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" px="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJ0pmXCg8MI/AAAAAAAAAJo/FSTGvWs5MEI/s320/581px-Orion_constellation_map.png" width="308" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Star Chart of Orion<br />(<a href="http://commons.wikimedia.org/wiki/File:Orion_constellation_map.png">image source</a>)</td></tr></tbody></table><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> The&nbsp;left shoulder is where you find the star <a href="http://www.astronomydj.com/2010/09/distance-to-stars.html">Betelgeuse</a>,&nbsp; an irregularly pulsating&nbsp;red supergiant star also known as Alpha Orionis.&nbsp; At a distance of a little over 500 light years,&nbsp;it varies in brightness from as bright at magnitude 0.4 to a drop&nbsp;down&nbsp;as low as magnitude&nbsp;1.2, over a main period of almost six years.&nbsp; </div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The&nbsp;star in the right shoulder is Bellatrix, or Gamma Orionis.&nbsp; Still bright at magnitude 1.6, Bellatrix is about 470 light years away, and 4000 times as luminous as our sun.</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The belt of Orion is made up of three stars,&nbsp;Zeta, Epsilon, and Delta, form east to west.&nbsp; Zeta Orionis is&nbsp;near two famous nebulae,&nbsp;the Flame Nebula, and the Horsehead Nebula (below).&nbsp;&nbsp;These can be glimpsed&nbsp;in large telescopes from dark locations.&nbsp; Time exposures reveal the colors and detail.</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TJzGnS6xVPI/AAAAAAAAAJk/mWZyIY97Wqk/s1600/horsehead+nasa.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" px="true" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TJzGnS6xVPI/AAAAAAAAAJk/mWZyIY97Wqk/s200/horsehead+nasa.jpg" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Zeta Orionis and <br />The Horsehead and Flame Nebulae<br />(<a href="http://commons.wikimedia.org/wiki/File:Horse_head_and_Flame-N.jpg">image source</a>)</td></tr></tbody></table> Orion's sword hangs&nbsp;below Zeta.&nbsp; Many people mistake the sword and belt of Orion for the "little dipper".&nbsp; 42 Orionis,&nbsp;Theta, and Iota Orionis are the&nbsp;three bright stars in the sword, from north to south.&nbsp; NGC 1977 surrounds 42 Orionis.&nbsp; Theta is a multiple gem at the heart of the Great Orion Nebula, M42.&nbsp; Iota is the bright star at the tip of the sword.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The sword region is&nbsp;a rich area for&nbsp;even small telescopes.&nbsp; The Orion Nebula is fantastic.&nbsp; A reasonably dark sky reveals a wealth of detail..&nbsp; The star Theta is a quadruple known as the Trapezium.&nbsp;&nbsp;This can also be studied in small telescopes at higher power.&nbsp; <a href="http://www.amazon.com/Burnhams-Celestial-Handbook-Observers-Universe/dp/048623567X">Burnham's Celestial Handbook</a> has detailed&nbsp;info and charts to make&nbsp;observing the Trapezium&nbsp;very enjoyable.&nbsp; I would highly recommend this addition to your library.&nbsp;&nbsp;</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />Here&nbsp;is a presentation from the Hubble Site detailing the magnificent Orion Nebula, M42.&nbsp; <a href="http://hubblesite.org/gallery/tours/tour-orion/">Click this link</a>.&nbsp;&nbsp;I hope you enjoy it!</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">See you under the stars,</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Dale&nbsp;</div></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"><br /></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-42869350506839384912010-09-19T21:44:00.008-05:002011-10-13T15:45:06.333-05:00Astronomy DJ says: Jupiter Looms Near <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJeflWgkqZI/AAAAAAAAAIs/yu-Fzn_Vxwk/s1600/699px-Jupiter-Earth-Spot_comparison.jpg" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="171" qx="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TJeflWgkqZI/AAAAAAAAAIs/yu-Fzn_Vxwk/s200/699px-Jupiter-Earth-Spot_comparison.jpg" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Jupiter-Earth-Red Spot <br />Size Comparison<br />(<a href="http://commons.wikimedia.org/wiki/File:Jupiter-Earth-Spot_comparison.jpg">image source</a>)</td></tr></tbody></table> <br />Whether you are new to astronomy or you have been around the block a few times, Jupiter is a favorite target.&nbsp; This fall, due to it's favorable position and&nbsp;apparent diameter,&nbsp;we have Jupiter at it's best.&nbsp;&nbsp;I would like&nbsp;to inspire you to <a href="http://www.astronomydj.com/p/big-telescopes-what-to-buy.html">go out and look</a> at it, but not in the same way as most sites are doing...<br /><a name='more'></a>&nbsp; <br /><br />Most of the online articles circulating the net right now&nbsp;are all repeating the same thing.&nbsp; Something along the lines of,&nbsp;"Jupiter is at opposition" (and what that means),&nbsp;how long it's been since the last time&nbsp;it was this close to earth (47 years), observing hints for beginners, and so on.&nbsp; Rather than re-wording the&nbsp;statistics and defining terms&nbsp;for the umpteenth time, I will instead relate a personal experience of my own regarding Jupiter.&nbsp; <br /><br />When I was 11, my dad bought me a small reflector telescope (my first)&nbsp;from Edmund Scientific for about $30.&nbsp; He helped me assemble it, explained a little about how it worked, and&nbsp;slyly launched me into&nbsp;astronomy.&nbsp; I didn't know anything at the time, really.&nbsp; I didn't know that&nbsp;several of the planets are the brightest objects in the sky, for instance.&nbsp; In my young brain stars were bright, and the&nbsp;planets were dim,&nbsp;because&nbsp;you had to have a telescope to see them well.&nbsp; <br /><br />My first night out, I wanted to look at Jupiter.&nbsp; I had just done a report in school for science class about Galileo,&nbsp;and I figured my little scope had to be better than his was, so I should be able to see Jupiter and four of it's moons just as Galileo had.&nbsp;&nbsp;It was&nbsp;supposed to be visible to the naked&nbsp;eye. &nbsp;I had&nbsp;studied my&nbsp;chart&nbsp;and determined about where Jupiter was supposed to be in the sky.&nbsp; I was armed and&nbsp;ready.&nbsp;  <br /><br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/_nlLwlwEXLHU/TJelUwu776I/AAAAAAAAAI8/c_gELOu__mc/s1600/Sagittarius-teapot-asterism.jpg" imageanchor="1" style="clear: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="160" qx="true" src="http://4.bp.blogspot.com/_nlLwlwEXLHU/TJelUwu776I/AAAAAAAAAI8/c_gELOu__mc/s200/Sagittarius-teapot-asterism.jpg" width="200" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Portion of the Constellation <br />Sagittarius<br />(<a href="http://commons.wikimedia.org/wiki/File:Sagittarius-teapot-asterism.jpg">image source</a>)</td></tr></tbody></table> One problem.&nbsp; Nobody told me how bright it was!&nbsp; Magnitude -2 sounded pretty faint to me.&nbsp; I assumed brighter objects would have <em>bigger</em> numbers.&nbsp; Made sense to me!&nbsp; I spent at least an hour examining every star I could see in that section of sky, getting more and more frustrated at each turn of the scope.&nbsp; This was nuts!&nbsp; It had to be one of those points of light.&nbsp; Back and forth from the chart to the scope I went, seemingly forever.&nbsp; I tried different magnifications thinking it was&nbsp;must be&nbsp;too small at low power to distinguish from a star.&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">I went inside and told my mom I was going crazy trying to find it.&nbsp; I went back out, stood looking up at the sky, and said, "forget it, I give up".&nbsp; Time to call it a night.&nbsp; Then I thought, well, I might as well look at that really bright star I've been skipping all night before I go in (the one star I was sure&nbsp;couldn't be&nbsp;Jupiter).&nbsp; I centered it, by now I was getting pretty good at aiming, focused, and almost fell over.&nbsp; It was Jupiter!&nbsp; Big and bright, a ball shaped object with even low power, and four moons all lined up pretty as you please.&nbsp; I have never felt so happy, and stupid, at the same time before or since!&nbsp; I ran inside and practically dragged my mom outside to look at it with me.&nbsp; I had to show some one!</div></div><br /> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TJeh7TDyvjI/AAAAAAAAAI0/0JDWd-j5hvU/s1600/hs-1999-13-c-small_web.jpg" imageanchor="1" style="clear: left; cssfloat: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" qx="true" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TJeh7TDyvjI/AAAAAAAAAI0/0JDWd-j5hvU/s320/hs-1999-13-c-small_web.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Hubble Image of Jupiter and Io.<br />(<a href="http://hubblesite.org/gallery/album/entire/pr1999013c/small_web/">image source</a>)</td></tr></tbody></table> That was how I started exploring our universe.&nbsp; By being a complete nit wit.&nbsp; But, I was hooked.&nbsp; For the next five years I spent many hours learning the sky with my little 3" reflector.&nbsp; The&nbsp;mirrors were&nbsp;OK, the mounting was mediocre, the finder was pointless, and the eyepieces were cheap.&nbsp; But I learned a&nbsp;lot about astronomy, and I had many fine hours of observing Jupiter.<br /><br />I would stay out all night timing occultations of the inner moon, or watching the progress of a moon shadow as&nbsp;the moon transited the planet.&nbsp; I could&nbsp;glimpse ( I think) the&nbsp;Great Red Spot on really&nbsp;good nights.&nbsp;&nbsp;Two equatorial belts were easy, sometimes a third one.&nbsp; With long hours&nbsp;at the eyepiece your&nbsp;ability to distinguish fine&nbsp;detail in brief moments of extreme clarity&nbsp;increases significantly.&nbsp; You don't&nbsp;see this talked about much,&nbsp;probably because not many do it, but it's true.<br /><br />Some of the&nbsp;articles on the net also read as if&nbsp;September 21st, the day of opposition, is going to be the day of days to look at&nbsp;Jupiter.&nbsp; Last chance, folks.&nbsp;&nbsp;Not so.<br /><br />Here's the good news.&nbsp; Jupiter is going to be <u>great</u> to look at for months.&nbsp; It will&nbsp;be higher and higher in the east at sunset each&nbsp;week.&nbsp; It's apparent diameter will only be slightly smaller&nbsp;in November than it is now, and it will be placed better for viewing in early evening.&nbsp; You aren't going to miss out if you don't see it with a telescope by next week.<br /><br />You will only be missing out if you never get around to it!<br /><br />Thanks for reading,<br /><br />Dale<br /><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-24180995027039976412010-09-18T18:50:00.004-05:002010-09-18T19:02:04.884-05:00A Night Under The StarsI recently learned of an observing site used by a local astronomy club.&nbsp;&nbsp;The night sky isn't perfect by any means, but it is way better than my suburban back yard.&nbsp; And, it's within about thirty minutes of my home.&nbsp; Needless to say, I was anxious to check it out.&nbsp; I got the chance last night...<br /><a name='more'></a><br />With the moon being about midway between first quarter and full I knew I wasn't going to see how&nbsp;dark it can get there, but I could at least check the place out.&nbsp; The sky was clear, so it looked like a go.&nbsp; I packed up my 80mm f/4 refractor, eyepieces, a couple of chairs, etc., and my eight year old son, and off we went.<br /><br />We arrived right at sundown.&nbsp; The moon was looking bright.&nbsp; Venus was low in the&nbsp;west.&nbsp; There was one other car there.&nbsp;&nbsp;The site looked pretty cool.&nbsp; A nice, unobstructed&nbsp;horizon, fairly well screened from the&nbsp;road and traffic lights.&nbsp; Roughly twelve (didn't stop to count)&nbsp;interconnected concrete observing pads with electrical outlets, spread out in a big fan shape.&nbsp; Two telescopes permanently&nbsp;on site.&nbsp; One 10" LX200, pier mounted in a roll off roof observatory, and a 16" dobsonian with goto/tracaking capability.&nbsp; Oh&nbsp;boy...what have I stumbled onto?<br /><br />People start showing up.&nbsp; The guy who operates the 10" LX200&nbsp;is one of the first.&nbsp; Over the course of the evening he provided nice views to many people, us included.&nbsp; He told me the&nbsp;County Parks division&nbsp;built and maintains the site in cooperation with the club as an outreach to the public.&nbsp; The place is open 24/7 to anyone who wants to use it!&nbsp; Every Friday, if it is clear, the club hosts an observing night for the public at large free of charge.&nbsp; Pretty cool.<br /><br />So, my son and I start setting up my little refractor and stuff, getting organized.&nbsp; We play catch with the football for a while, waiting for it to get a little darker.&nbsp; I notice&nbsp;Jupiter very low in the east.&nbsp; I can just pick out Altair&nbsp;through the glare of the moon in the twilit sky.&nbsp;&nbsp;Time to put up the football.<br /><br />More people are showing up.&nbsp; About&nbsp;seven telescopes are&nbsp;operating, plus mine.&nbsp; Some people without scopes are mingling in with those of us that have them.&nbsp; I think I'm the only one with a scope that isn't in the club.&nbsp; A guy with two children asks me what I'm looking at and I'm off and running.&nbsp;&nbsp;I spent about an hour and a half with them, giving a nice tour of the sky and answering questions.&nbsp; We all took turns looking through&nbsp;my little&nbsp;scope at different objects, saving the moon for last.&nbsp; <br /><br />A little later another guy form the club&nbsp;shows up and&nbsp;uncovers the 16" dobsonian.&nbsp; My son and I wander over as he is zeroing in on M13, a bright globular cluster in Hercules,&nbsp;and he invites us to have a look.&nbsp; It was awesome, even in bright moon light.&nbsp; Countless stars fill the field in tight little chains.&nbsp; Really pretty.&nbsp; I can only imagine how it would look with no moon.&nbsp; Next he goes for M57, the&nbsp;Ring Nebula in Lyra.&nbsp;&nbsp;A very well defined ring with lots of fine&nbsp;detail visible.&nbsp; The scope had very crisp images.<br /><br />We stayed a while longer and looked at Jupiter some more through a much smaller&nbsp;6" dobs.&nbsp; I was never the less impressed with the views it provided.&nbsp;&nbsp;On the way home we talked about&nbsp;what&nbsp;we had seen and done and how much fun it was.&nbsp; I look forward to many returns to the area in the future.&nbsp;&nbsp;I've always been kind of a loner when it comes to astronomy, but that was so much fun I'm thinking of joining the club.<br /><br />Happy viewing!<br /><br />DaleDJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0tag:blogger.com,1999:blog-7808051055748780951.post-66255890742704636572010-09-15T09:39:00.014-05:002012-02-09T14:39:22.797-06:00The Distance to the Stars <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/_nlLwlwEXLHU/TJDb6yb_e2I/AAAAAAAAAH8/mPtg7HsqxcM/s1600/hst_betelgeuse.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" qx="true" src="http://1.bp.blogspot.com/_nlLwlwEXLHU/TJDb6yb_e2I/AAAAAAAAAH8/mPtg7HsqxcM/s320/hst_betelgeuse.jpg" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">This is the first direct image of a star other than the Sun, made with NASA's Hubble Space Telescope. Called Alpha Orionis, or Betelgeuse, it is a red supergiant star marking the shoulder of the winter constellation Orion the Hunter<br />(<a href="http://hubblesite.org/newscenter/archive/releases/1996/04/image/a/results//">image source</a>)</td></tr></tbody></table>The other night, a coworker asked me a common question people have when I'm rambling on about this or that star in the sky and mention it's distance.&nbsp; "How do we know how far away it is to a given star?"&nbsp; Actually, it's a very good question, since there isn't a short answer that is very complete.<br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a name='more'></a> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The first method of measuring the distance to the stars was accomplished in 1838 by a fellow named <span style="color: black;">Friedrich Wilhelm Bessel.&nbsp; He used trigonometric parallax to closely estimate the distance to the star 61 Cygni.&nbsp; </span>He carefully measured the angular motion of the star against the background stars as seen from earth six months apart, thereby using the diameter of earth's orbit around the sun as a baseline.</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; float: right; margin-bottom: 1em; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/_nlLwlwEXLHU/TI9zi5N6owI/AAAAAAAAAHs/0oXpfPZ04uw/s1600/381px-Tycho_Brahe_instrument_sextant.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" qx="true" src="http://3.bp.blogspot.com/_nlLwlwEXLHU/TI9zi5N6owI/AAAAAAAAAHs/0oXpfPZ04uw/s320/381px-Tycho_Brahe_instrument_sextant.jpg" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Tycho Brahe's Two Person Sextant<br />(<a href="http://commons.wikimedia.org/wiki/File:Tycho_instrument_sextant_16.jpg">image source</a>)</td></tr></tbody></table>Place a finger at arms length and first close one eye, then switch eyes, and you will notice the finger appears to move relative to the background.&nbsp; You can measure the angle from your finger to your two eyes,&nbsp;the distance between your eyes, and use trigonometry to determine the distance from your two eyes to your finger.&nbsp; That's a simplified version of the process.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> The problem with this method is that the angle measured is so tiny,&nbsp;only the closest stellar neighbors can be measured.&nbsp; It did get us started though.&nbsp; Modern instrumentation has increased the distances that can be measured with this method out to&nbsp;a couple thousand&nbsp;light years.&nbsp; Sounds like a lot, but our galaxy alone is around 100,000 light years in diameter.&nbsp; So how do they measure the larger distances?</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The short answer...?&nbsp; A combination of several&nbsp;methods, cross referenced against each other, yielding a reasonable estimate.&nbsp; Always subject to refining, of course.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><u>Those methods include</u>:&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The inverse square law:&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />Think of a star as a if it were a light bulb.&nbsp; The light bulb has an intrinsic brightness level (or luminosity), say for instance 25 watts.&nbsp; Depending on how far away you are, the light bulb will <em>appear </em>to be brighter or dimmer (apparent magnitude).&nbsp; If we know the luminosity, the distance can be estimated by measuring the apparent magnitude and applying the inverse square law.&nbsp; Luminosity can be determined by spectral comparison to other stars of known distance (measured by parallax).</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Cepheid Variables: </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Many stars have significant variation in brightness and are loosely referred to as variable stars.&nbsp; One type is called a Cepheid Variable, named after&nbsp;Delta Cephei&nbsp;in the constellation Cepheus.&nbsp; This type of variable is unique in that the relationship of it's luminosity to it's pulsation period is very precise.&nbsp; They are also very massive and bright, making them visible even in distant galaxies beyond our own.&nbsp; The Hubble ST has identified Cepheids out to around 100 million light years.&nbsp; As long as the distance to one Cepheid variable in our own galaxy&nbsp;is known, the others can be calculated.&nbsp; </div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; cssfloat: right; cssfloat: right; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/_nlLwlwEXLHU/TJDYIkid-2I/AAAAAAAAAH0/ypy9tdjcNs0/s1600/Variable_Stars_in_a_Distant_Spiral_Galaxy.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="177" qx="true" src="http://2.bp.blogspot.com/_nlLwlwEXLHU/TJDYIkid-2I/AAAAAAAAAH0/ypy9tdjcNs0/s320/Variable_Stars_in_a_Distant_Spiral_Galaxy.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><div class="description en" lang="en" xml:lang="en">&nbsp; At 108 million light-years, NGC 4603 is&nbsp;the most distant <br />galaxy in which Cepheid variables have been found </div><div class="description en" lang="en" xml:lang="en">&nbsp;(<a href="http://commons.wikimedia.org/wiki/File:Variable_Stars_in_a_Distant_Spiral_Galaxy_-_GPN-2000-000940.jpg">image source</a>)</div></td></tr></tbody></table> These are just three of the many methods employed to determine the immense distances in our universe.&nbsp; None of them are perfect, but they combine to give a fairly good picture overall.<br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">That's enough for one day!</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Dale</div></div><br /></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> <br /><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"></div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br /></div></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"></div>DJhttp://www.blogger.com/profile/15742228811577738159noreply@blogger.com0