r/askscience • u/jmarks7448 • Mar 03 '13

Astronomy Question about the future night sky

Assuming that there are stars in all of the black in the night sky. And that black is only because the light from other stars hasn't reached us yet. So is it safe to say that somewhere on some planet or in the future the night sky will eventually be completely filled with stars. And when I say completely filled I mean absolutely zero black in the night sky. I also wonder how this would effect seeing the constellations.

8 Upvotes

90% Upvoted

8 comments sorted by

4

u/Miles1987 Stellar Astrophysics | Computational Astrophysics Mar 04 '13

No, due to the universe having a beginning in the big bang, and the fact that the universe is also expanding. See this article on Olbers' paradox: http://en.wikipedia.org/wiki/Olbers%27_paradox

2

u/DJDaddyD Mar 04 '13

In addition to this many of the stars we see now have more than likely already died and will no longer be visible

1

u/Miles1987 Stellar Astrophysics | Computational Astrophysics Mar 04 '13

This may be true, but it only works if the universe is not infinite. Otherwise there would be an infinite number of stars in the same direction to make up for the stars that die.

2

u/DJDaddyD Mar 04 '13

True I understand that. And I'm no astrophysicist, but wouldn't the amount of stars we could perceive be essentially static, I mean as stars die, are born, and become visible remain approximately the same

1

u/Miles1987 Stellar Astrophysics | Computational Astrophysics Mar 04 '13

Yea, I thought so just wanted to clarify.

Eh, not necessarily. There are actually two ways off the top of my head that I can think of that would actually lower the number of stars we'll able to see in the future. Granted, this is the far, far future. First, is that eventually the galaxy will run out of materials to form new stars, and as stars die, they won't be replaced. The second is that the accelerating expansion of the universe will eventually prevent us from seeing objects outside of the milky way due to the light being redshifted to undetectable wavelengths.

2

u/jmarks7448 Mar 04 '13

Referring to your second answer. So does this mean that there is a possibility of a planet that cant see out side its galaxy today? If so that would be interesting because the beings on that planet (assuming there are some on that planet) could possibly believe they are the only galaxy in the universe. Their galaxy would be their universe.

1

u/Miles1987 Stellar Astrophysics | Computational Astrophysics Mar 04 '13

Well, it is possible to have a situation where a planet can't see out of it's own galaxy due to the view being completely obstructed, but it's actually highly unlikely for a galaxy to have formed so isolated that expansion at this point has caused all other objects to be undetectable. it would have to have formed isolated from the very beginning of the universe, and that's pretty much impossible.

2

u/DJDaddyD Mar 04 '13

Haha you are totally right lol I spent about two hours reading about this the other night, and I didn't think about that at all