They say that when we look up to see stars, we’re actually seeing the light from dead stars. So technically, we can’t see what’s out there in the present? What do you think is out there now? is it just new, modern stars or we don’t get to see anything at all? (since by now, everything has expanded billions of miles apart from each other that light is far from anything to reach)
In: Planetary Science
When you are looking at the stars with your unaided eyes, 75% of them are within 500 light years. 90% of them are within 1100 light years. So unaided, what you see is younger than the Roman empire and most is younger than the oldest university in the english speaking world.
As for what we can see with a telescope… Stars have lifecycles and we can estimate where stars are on this (by size, emission spectrum, etc). We can also observe how they are moving and, along with all the other gravitational sources, predict their path. Thus we can and do make pretty good models of what distant galaxies look like now. In fact one thing we do to test theories is to model young ( far away ) galaxies we see, simulate their temporal evolution, and see if they look like the closer, older galaxies. (Simplified for eil5).
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