# A question about the stars we see **URL:** \ **Category:** Factual Questions\ **Created:** [January 18, 2013, 6:50pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638 "2013-01-18T18:50:51Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [January 18, 2013, 10:43pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/21 "2013-01-18T22:43:34Z")
The numbers get mind blowing very quickly. I just did a quick back-of-a-fag-packet calculation using a conservative estimate of stars in our galaxy, try this… Imagine a poster 34 metres by 55 metres made up of individual A2 printouts from a 16mp camera. if…_.if_ you can make out individual pixels then each one will represent a star in our galaxy. More likely that massive poster should be twice the size. The real mind-blower is that there are at least as many galaxies in the universe as stars in our galaxy. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [January 18, 2013, 11:14pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/22 "2013-01-18T23:14:33Z")
> [@artemis](#): > > Our visual acuity is nowhere near good enough to resolve the individual stars that make up the “cloud.” You need a big telescope to do that. Specifically, it took the 100 inch aperture telescope on Mt. Wilson, a very long exposure and a night of exceptionally good seeing during WW1. The war is relevant because the astronomer that took the photo was German, so was rejected for war duties. His colleagues being off fighting meant he got more time on what was then the worlds largest telescope. Up until then, many astronomers did not accept that these nebula were actually galaxies of stars. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [January 18, 2013, 11:53pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/23 "2013-01-18T23:53:44Z")
> [@artemis](#): > > Treat yourself some time to a dark sky vacation. Head off to somewhere very remote and very dark - with your telescope, if possible, with binoculars if not - and see the sky as it was meant to be seen. You’ll be stunned. On a trip to Hawaii, I was once at the summit of Haleakala at sunset. After witnessing a super-glorious sunset, I stuck around to watch the stars come out. A while later, there was this huge irregular cloud across the sky, and I heard a guy cursing that the cloud was covering the Milky Way. I informed him that the cloud WAS the Milky Way. The guy then turned on his camera’s flash, to make the galaxy brighter. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [January 19, 2013, 12:03am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/24 "2013-01-19T00:03:43Z")
Oh, and by the way . . . that Andromeda Galaxy? If you wait long enough, it’ll be [a whole lot closer](http://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision). ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [January 19, 2013, 1:20am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/25 "2013-01-19T01:20:34Z")
> [@tdn](#): > > I’ve tried looking at it with my telescope. Nope. Not there. Not even close. > > I really need to get out of the city. > [@artemis](#): > > Treat yourself some time to a dark sky vacation. Head off to somewhere very remote and very dark - with your telescope, if possible, with binoculars if not - and see the sky as it was meant to be seen. You’ll be stunned. And another tip, if you’re fairly new at stargazing: Spend some time outside at night (like a half-hour or more) so your night vision is up to speed. When I was a young-un, we went to a mountain resort for weekends from time to time. Good dark sky, away from the city light pollution. Sometimes we sat out at night just to look at stars. Try this: (a) Go outside, out of the bright indoor light. Look at sky. Take a mental photograph of the stars you see. (b) Stay outside for a while – 30 to 60 minutes. Wear a warm jacket. (c) Now take another mental photo of the stars you see, and compare with first mental photo. Be prepared to be astonished at how many more stars you see now than at first. In that length of time watching, you can also spot satellites. They look just like stars, but moving slowly across the sky (relative to other stars). I suppose the geosynchronous satellites would appear to be stationary. But you can see other satellites moving, if you watch long enough. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 19, 2013, 2:07am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/26 "2013-01-19T02:07:59Z")
> [@panache45](#): > > On a trip to Hawaii, I was once at the summit of Haleakala at sunset. After witnessing a super-glorious sunset, I stuck around to watch the stars come out. A while later, there was this huge irregular cloud across the sky, and I heard a guy cursing that the cloud was covering the Milky Way. I informed him that the cloud WAS the Milky Way. That’s always a fun experience, blowing newbies’ minds. (Too bad he then went on to blow your dark adaptation.) With any luck, I’ll be spending a week this coming summer in a place so dark the Milky Way actually casts a faint shadow. The visual limiting magnitude is around 7.1 or better on a very good night. Needless to say, it’s going to be a treat! It’s really sad that the average person (who now dwells in a city or suburbia) has no idea what the sky really looks like. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 19, 2013, 2:09am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/27 "2013-01-19T02:09:03Z")
> [@panache45](#): > > Oh, and by the way . . . that Andromeda Galaxy? If you wait long enough, it’ll be [a whole lot closer](http://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision). And wouldn’t that be an incredible sight to see! (Or maybe not, considering the radiation levels that event is likely to unleash.) ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [January 19, 2013, 2:15am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/28 "2013-01-19T02:15:49Z")
[A video](http://www.sciencefriday.com/video/12/21/2012/shooting-stars.html) about some amazing time lapse astrophotography from dark sky locations folks posting here might enjoy. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [January 19, 2013, 2:47am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/29 "2013-01-19T02:47:21Z")
> [@Frazzled](#): > > That being said - there are certain specific types of nova and supernova that can be detected in other galaxies but that’s not what features in the pictures we normally see. I don’t know that it’s ever happened, but in principle you could likely see a large supernova in another galaxy. Modest scopes can detect them, so it’s not too hard to imagine one being just at the limit of human vision if the conditions are right. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 19, 2013, 3:05am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/30 "2013-01-19T03:05:59Z")
> [@Dr.Strangelove](#): > > I don’t know that it’s ever happened, but in principle you could likely see a large supernova in another galaxy. In 1987 there was a supernova in the Large Magellanic Cloud (which is technically a separate galaxy from our own, though it orbits the Milky Way) which was visible to the naked eye. So it has happened at least once, although in a very close galaxy. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [January 19, 2013, 4:54am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/31 "2013-01-19T04:54:57Z")
> [@panache45](#): > > Oh, and by the way . . . that Andromeda Galaxy? If you wait long enough, it’ll be [a whole lot closer](http://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision). What I find even more mind-boggling: While the Andromeda Galaxy contains about one trillion stars and the Milky Way contains about three hundred billion; the chance of even two stars colliding is negligible because of the huge distances between each pair of stars. For example, the nearest star to the Sun is Proxima Centauri, about 3x10[sup]7[/sup] solar diameters (4x10[sup]13[/sup] km or 4.2 ly) away. If the Sun were a ping-pong ball in Paris, the equivalent Proxima Centauri would be a pea-sized ball in Berlin (and the Milky Way would be about 1.9x10[sup]7[/sup] km wide, about a third of the distance to Mars). Stars are much denser near the centres of each galaxy with an average separation of only 1.6x10[sup]11[/sup] km. But that is still a density which represents one ping-pong ball every 3.2 km. Thus, it is extremely unlikely that any two stars may collide. I love how even when you try to scale-down stellar distances, i.e. ping-pong balls in Paris & Berlin, even at that scale they still involve literally \*astronomical \*distances (i.e. a third of the way to Mars!) ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [January 19, 2013, 5:34am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/32 "2013-01-19T05:34:51Z")
> [@Laggard](#): > > But there are stars between galaxies, correct? So you could be seeing stars outside the milky way? > [@Laggard](#): > > Hmmm > > [http://curious.astro.cornell.edu/question.php?number=384](http://curious.astro.cornell.edu/question.php?number=384) > [Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos](http://uk.answers.yahoo.com/question/index?qid=20090916145831AAmDxPq) Yes, there are a few, but they are still way, way too far away to be seen by the naked eye. All the stars we see at night are not only in the Milky Way, they are in our local, small area of the Milky Way, a very small part of the galaxy as a whole. Under good seeing conditions it is possible to see the central parts of the Milky Way (where the stars are much closer together than where we are, some way out from the center) as a faint, irregular band of light across the sky. “Milky Way” originally meant this band of whitish light, long before anything was understood about galaxies, because it was thought to look like spilled milk. (I believe the mythical account was that it was the breast milk of Andromeda.) With a telescope you can see that it is made up of millions of distant stars (Galileo was the first person to see this), but there is no way to see this without a telescope. Then there are going to be many stars in the more outlying parts of the galaxy on eh other side that we cannot see any trace of with the naked eye. There is no chance of seeing extra-galactic stars. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 19, 2013, 6:38am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/33 "2013-01-19T06:38:17Z")
> [@njtt](#): > > Under good seeing conditions it is possible to see the central parts of the Milky Way (where the stars are much closer together than where we are, some way out from the center) as a faint, irregular band of light across the sky. Minor nit: under skies that are not light-polluted, there is NOTHING faint about the Milky Way! If you want faint, try looking for the [gegenschein](http://en.wikipedia.org/wiki/Gegenschein) or the [Zodiacal\_light](http://en.wikipedia.org/wiki/Zodiacal_light). The Milky Way is bright and obvious. That most people think it is faint is just proof that they’ve never stood under a truly dark sky. ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [January 19, 2013, 11:56am UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/34 "2013-01-19T11:56:48Z")
> [@artemis](#): > > In 1987 there was a supernova in the Large Magellanic Cloud (which is technically a separate galaxy from our own, though it orbits the Milky Way) which was visible to the naked eye. So it has happened at least once, although in a very close galaxy. That’s what I dropped into this thread to say, here is the wiki [link](http://en.wikipedia.org/wiki/SN1987A). It peaked at about magnitude 3, so while visible to the naked eye, it would have been quite difficult to spot. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [January 19, 2013, 2:23pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/35 "2013-01-19T14:23:42Z")
> [@Kevbo](#): > > Specifically, it took the 100 inch aperture telescope on Mt. Wilson, a very long exposure and a night of exceptionally good seeing during WW1. The war is relevant because the astronomer that took the photo was German, so was rejected for war duties. His colleagues being off fighting meant he got more time on what was then the worlds largest telescope. Up until then, many astronomers did not accept that these nebula were actually galaxies of stars. Who was this guy? Because as far as I know nobody accepted that the nebulae were galaxies until Hubble proved they were much too far away to be in our own galaxy, in 1922-23, well after WW1. And the way he did it was through studying the red shift, not by taking a particularly sharp picture. Your mention of Mt. Wilson implies you’re talking about Hubble, but your time frame is too early and besides, Hubble wasn’t German, and he served in the US Army during both WW1 and WW2. > **[Edwin Hubble](https://en.wikipedia.org/wiki/Edwin_Hubble#The_universe_goes_beyond_the_Milky_Way_galaxy)** > > Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. > Hubble proved that many objects previously thought to be clouds of dust and gas and classified as "nebulae" were actually galaxies beyond the Milky Way. He used the strong direct relationship between a classical Cepheid variable's luminosity and pulsation period (discovered in 1908 by Henrietta Swan... ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [January 19, 2013, 2:36pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/36 "2013-01-19T14:36:09Z")
> [@artemis](#): > > Minor nit: under skies that are not light-polluted, there is NOTHING faint about the Milky Way! If you want faint, try looking for the [gegenschein](http://en.wikipedia.org/wiki/Gegenschein) or the [Zodiacal\_light](http://en.wikipedia.org/wiki/Zodiacal_light). The Milky Way is bright and obvious. That most people think it is faint is just proof that they’ve never stood under a truly dark sky. Faint is a relative term. Even in the best seeing conditions, the Milky Way is faint compared to the stars and planets you can see. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 19, 2013, 4:40pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/37 "2013-01-19T16:40:36Z")
> [@Alka\_Seltzer](#): > > That’s what I dropped into this thread to say, here is the wiki [link](http://en.wikipedia.org/wiki/SN1987A). It peaked at about magnitude 3, so while visible to the naked eye, it would have been quite difficult to spot. Magnitude 3 is actually not very hard to spot except in urban areas and some suburban locations. The hard part would be knowing the appearance of the Large Magellanic Cloud well enough to notice that it had changed, and now contained a “new” star. At that magnitude, the supernova wouldn’t jump out to the casual stargazer, but someone who was specifically looking for it wouldn’t have much trouble finding it. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 19, 2013, 4:43pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/38 "2013-01-19T16:43:32Z")
> [@njtt](#): > > Faint is a relative term. Even in the best seeing conditions, the Milky Way is faint compared to the stars and planets you can see. Under the best seeing conditions (as **panache45** ’s story shows), the Milky Way is about the same brightness as a cloud lit from below at night, which is something most people have no trouble seeing and recognizing. It’s not setting the sky ablaze like the moon or Sirius, but it’s not at all hard to spot. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 19, 2013, 5:57pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/39 "2013-01-19T17:57:19Z")
Actually, I think SN1987a _was_ originally discovered by someone actually looking up with his naked eye and noticing an “extra” star in the LMC. Which was very quickly followed up with telescopic observations, of course. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [January 19, 2013, 6:35pm UTC](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638/40 "2013-01-19T18:35:27Z")
Well this is right on cue: [A zoomable Milky Way](http://www.astrosurf.com/sguisard/Pagim/GC.html). [Previous page](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638.md?page=1) [Next page](https://boards.straightdope.com/t/a-question-about-the-stars-we-see/647638.md?page=3)