# Stars in Space **URL:** \ **Category:** Factual Questions\ **Created:** [November 10, 2006, 9:44am UTC](https://boards.straightdope.com/t/stars-in-space/379850 "2006-11-10T09:44:24Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Alive\_At\_Both\_Ends](https://avatars.discourse-cdn.com/v4/letter/a/73ab20/32.png) [@Alive\_At\_Both\_Ends](https://boards.straightdope.com/u/Alive_At_Both_Ends)\ **Post date:** [November 10, 2006, 5:27pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/21 "2006-11-10T17:27:03Z")
[QUOTE=Whack-a-Mole] Huh? Looking away from the center there just aren’t many stars left such that you see the bright band that you do when looking towards the center of the galaxy. I am not following what you are getting at. [/QUOTE] Take a look at [this](http://www.astro.lu.se/Resources/Vintergatan/milkyway.gif). It is a 360 degree panoramic view of the Milky Way as seen from Earth, done in the 1940’s. It shows the bright band extending right around the sky as I said. It’s true that even the slightest bit of light pollution will wipe out the fainter bits, though. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [November 10, 2006, 5:36pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/22 "2006-11-10T17:36:11Z")
_Please_ could we get the Olbers’ “Paradox”\* discussion out of this thread? There are many people who have published research papers over the decades that point out a trivial explanation that has nothing to age/size/expansion of the Universe. It’s more of a GD issue at this point than a GQ topic. The OP wasn’t asking about Olbers’ “Paradox”, so why dirty up this thread? - Halley’s if you prefer. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [November 10, 2006, 5:44pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/23 "2006-11-10T17:44:19Z")
[QUOTE=BACI] Incorrect camera appertures perhaps? Just a thought. [/QUOTE] You have it in one. In order to catch the faint light of the background stars on film, the F-stop would have to be set so that the foreground object would be seriously overexposed. This is also the reason why you cannot see stars in photos from the Apollo missions. ---
**Author:** ![MarcusF](https://avatars.discourse-cdn.com/v4/letter/m/67e7ee/32.png) [@MarcusF](https://boards.straightdope.com/u/MarcusF)\ **Post date:** [November 10, 2006, 8:24pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/24 "2006-11-10T20:24:17Z")
> [@](#): > > Originally posted by ftg: > Please could we get the Olbers’ “Paradox”\* discussion out of this thread? There are many people who have published research papers over the decades that point out a trivial explanation that has nothing to age/size/expansion of the Universe. As a Guest I’m sorry if I’ve rattled someone’s cage. Mentioning Olber’s (or whoever’s) paradox seemed necessary to address Pullet’s posts. I had no idea that there was a “trivial” explanation that could be the subject of a Great Debate! I’m interested - can you give a cite? ---
**Author:** ![RaftPeople](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@RaftPeople](https://boards.straightdope.com/u/RaftPeople)\ **Post date:** [November 10, 2006, 9:11pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/25 "2006-11-10T21:11:36Z")
[QUOTE=MarcusF] The answer to 2) is more interesting. You’ve hit on “Olber’s Paradox”: which can be put as ‘If the universe is infinite, and there are stars in all directions, which ever direction we choose to look in we should be able to see stars. Any line of sight should eventually intersect with a star, so all the sky should be bright.’ There are a number of possible answers but the generally accepted one is that the universe is not infinitely old and, as the speed of light is finite, there hasn’t been time for the light from stars further than a certain distance to reach us yet. In fact Olber’s Paradox is taken as evidence of the Big Bang. [/QUOTE] And just to add to that, because the rate of expansion of the universe exceeds the speed of light, the number of stars whose light can ever reach us has been decreasing over time. ---
**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:** [November 10, 2006, 9:33pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/26 "2006-11-10T21:33:26Z")
Have you ever taken a picture of anything at night, right here on Earth? You’ll either get a good picture of whatever you’re taking a picture of, but no stars in the picture, or you’ll get a picture of nothing but stars. As the Hubble proves, you can certainly get great pictures of stars from space. But the Hubble is trying to get pictures of stars, while the guy running the IMAX camera during a spacewalk isn’t trying to get stars. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 10, 2006, 9:42pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/27 "2006-11-10T21:42:49Z")
[QUOTE=Chronos] You’ll either get a good picture of whatever you’re taking a picture of, but no stars in the picture, or you’ll get a picture of nothing but stars. [/QUOTE] [Sne](http://antwrp.gsfc.nasa.gov/apod/ap060801.html) [rk!](http://antwrp.gsfc.nasa.gov/apod/ap010514.html) Usually, not _always_🙂 ---
**Author:** ![Algernon](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Algernon](https://boards.straightdope.com/u/Algernon)\ **Post date:** [November 10, 2006, 10:42pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/28 "2006-11-10T22:42:07Z")
[QUOTE=ftg] _Please_ could we get the Olbers’ “Paradox”\* discussion out of this thread? There are many people who have published research papers over the decades that point out a trivial explanation that has nothing to age/size/expansion of the Universe. It’s more of a GD issue at this point than a GQ topic. The OP wasn’t asking about Olbers’ “Paradox”, so why dirty up this thread? [/QUOTE] I too would like my ignorance fought. Could you shed some light on your post? I’d love to hear the trivial explanation. (and I’m not being sarcastic in my request either, in case it comes across that way.) ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [November 11, 2006, 5:55am UTC](https://boards.straightdope.com/t/stars-in-space/379850/29 "2006-11-11T05:55:35Z")
[QUOTE=Algernon] I too would like my ignorance fought. Could you shed some light on your post? I’d love to hear the trivial explanation. (and I’m not being sarcastic in my request either, in case it comes across that way.) [/QUOTE] I cannot speak for what **ftg** was thinking but the only “simple” solution to Olbers’ Paradox I have heard is that intervening “stuff” (space dust or what have you) will absorb much of the light. The counter to this is eventually this “stuff” would heat up and emit light as well but I suppose one could say there hasn’t been enough time for that heating to occur (actually I never understood that part…I cannot imagine distant stars heating anything sufficiently to emit light but then IANAAstronomer/Physicist). ---
**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:** [November 11, 2006, 6:29am UTC](https://boards.straightdope.com/t/stars-in-space/379850/30 "2006-11-11T06:29:43Z")
> [@](#): > > Usually, not always Hmm, usually pictures like that are made with double exposures, but the second link explicitly says that the buildings are lit only by starlight. I wonder how they managed that? Digital photography with clever data processing, perhaps? ---
**Author:** ![drewbert](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drewbert/32/15890_2.png) [@drewbert](https://boards.straightdope.com/u/drewbert)\ **Post date:** [November 11, 2006, 2:22pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/31 "2006-11-11T14:22:14Z")
[QUOTE=Chronos] Hmm, usually pictures like that are made with double exposures, but the second link explicitly says that the buildings are lit only by starlight. I wonder how they managed that? Digital photography with clever data processing, perhaps? [/QUOTE] That one _is_ a little baffling. Could it have been taken with really, really fast photographic film? Usually, taking a picture with that many stars would require the camera to be fixed to a motor to track the stars’ motion (otherwise the long exposure required would result in long streaks instead of points.) But if the camera was moving, then the observatory would be a big blur. Fast film and a relatively short exposure time might be how this was done. Incidentally, since I don’t think it’s been explicitly mentioned, the reason we see the Milky Way as a band across the sky is because the galaxy is a flat shape and we’re inside it (actually more like 2/3 of the way out from the center). The rest of the stars in the sky are also part of the Milky Way Galaxy, but they’re closer to us and aren’t as many of them so they appear more spread apart. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 11, 2006, 3:11pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/32 "2006-11-11T15:11:15Z")
[QUOTE=drewbert] Could it have been taken with really, really fast photographic film? [/QUOTE] The photo _is_ black and white, and there’s a fairly simple protocol for pushing Tri-X up to ASA-2000, not that I can remember it after 30 years. [Hypersensitization of the film with hydrogen gas](http://www.astropix.com/HTML/I_ASTROP/I09/I09.HTM) is also a possibility. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [November 11, 2006, 5:25pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/33 "2006-11-11T17:25:12Z")
[QUOTE=Whack-a-Mole] IANAAstronomer but the answer to your question is yes, we are on the edge of the Milky Way about 26,000 light years from the center. This [link](http://www.enchantedlearning.com/subjects/astronomy/solarsystem/where.shtml) gives a picture of where the earth is in relation to the rest of the galaxy (not a very good picture sadly but good enough for this purpose). When you see the Milky Way in the night sky you are looking in towards the center of our galaxy. [/QUOTE] If we lived near the center, would we see thousands of first magnitude and brighter stars crowding the sky, even from large cities? ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [November 11, 2006, 5:47pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/34 "2006-11-11T17:47:42Z")
So what about the stars, though? Astronauts can see them can’t they? Yet they never mention them. I always supposed the reason they don’t appear in space snapshots is the same reason they don’t usually appear in nighttime pictures taken from Earth. The film isn’t exposed long enough; if it were, the mostly white space suits, vehicles and other equipment would appear so washed out you wouldn’t be able to see anything. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [November 11, 2006, 5:57pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/35 "2006-11-11T17:57:05Z")
Take a camera and point at the starry sky one night. What image appears? Where did the stars go? Try the same experiment using the moon as your subject. How did your picture of the moon come out? Why? ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 11, 2006, 6:14pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/36 "2006-11-11T18:14:26Z")
[QUOTE=Spectre of Pithecanthropus] If we lived near the center, would we see thousands of first magnitude and brighter stars crowding the sky, even from large cities? [/QUOTE] Here’s an [IR shot of the central two light years of the milky way](http://antwrp.gsfc.nasa.gov/apod/ap021018.html). LOTS of stars, and at 30,000 LY distance, they have to be damn bright for earthly scopes to see them. I don’t think we’d see _anything_ from the surface of a planet near the center; the radiation would kill us first. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [November 11, 2006, 8:36pm UTC](https://boards.straightdope.com/t/stars-in-space/379850/37 "2006-11-11T20:36:54Z")
[QUOTE=Spectre of Pithecanthropus] If we lived near the center, would we see thousands of first magnitude and brighter stars crowding the sky, even from large cities? [/QUOTE] Similar question: If we were all the way out on the rim (rather than most of the way as we are now), we’d see the “Milky Way” streak only half the year, yes? Presuming the same sort of precession we have now. When looking back at the galaxy, we’d see the streak; when looking out away from it (i.e. with the galaxy “under” our feet, on the other side of the world) we’d see a normal starry sky. Yes? ---
**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:** [November 12, 2006, 2:53am UTC](https://boards.straightdope.com/t/stars-in-space/379850/38 "2006-11-12T02:53:16Z")
> [@](#): > > Similar question: If we were all the way out on the rim (rather than most of the way as we are now), we’d see the “Milky Way” streak only half the year, yes? Well, across half of the sky. Depending on the planet’s orbital plane and axis, that could manifest as being visible for only half the year, or only visible from one hemisphere, or some combination. But the sky in other directions probably wouldn’t exactly look “normal”, since the density of stars would probably be lower out there. This is mentioned, incidentally, in one of Asimov’s _Foundation_ books (the planet on which much of the events take place is way out on the rim). ---
**Author:** ![Steve\_MB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steve_mb/32/5339_2.png) [@Steve\_MB](https://boards.straightdope.com/u/Steve_MB)\ **Post date:** [November 12, 2006, 5:28am UTC](https://boards.straightdope.com/t/stars-in-space/379850/39 "2006-11-12T05:28:07Z")
[QUOTE=MonkeyMensch] Actually, you can see thousands of individual stars at night. I think the number of stars visible to the naked eye is around six thousand. [/QUOTE] That’s the number of stars in the entire sky visible to the naked eye. Of course, half of the celestial sphere is below the horizon, and the portion of it that is not far above the horizon is somewhat more blocked by the atmosphere than the portion of it that is more or less straight up – between those two factors, you can see about 2500 stars on any given night under ideal conditions. ---
**Author:** ![Steve\_MB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steve_mb/32/5339_2.png) [@Steve\_MB](https://boards.straightdope.com/u/Steve_MB)\ **Post date:** [November 12, 2006, 5:31am UTC](https://boards.straightdope.com/t/stars-in-space/379850/40 "2006-11-12T05:31:33Z")
[QUOTE=Alive At Both Ends] The idea that redshift causes distant galaxies to become invisible is based on a misunderstanding of the redshift. Actually, galaxies radiate in just about all parts of the electromagnetic spectrum, so all that happens is that the ultraviolet light emitted by these galaxies redshifts into the visible range. Therefore you can still see them. The true explanation of Olbers’ paradox is as explained by **MarcusF**. [/QUOTE] In general, the total electromagnetic energy delivered is reduced by the red shift. Specifically, the amount of visible light from just about any naturally occuring source is reduced by the red shift (something has to be **very** hot, well above most stellar surface temperatures, for its peak thermal energy emissions to be in the ultraviolet). [Previous page](https://boards.straightdope.com/t/stars-in-space/379850.md?page=1) [Next page](https://boards.straightdope.com/t/stars-in-space/379850.md?page=3)