question of the past....?

Question

my question is, stars, if all we see is the light that is produced by the stars and well some stars are 100's of light years away, how do we know what we are looking at is really there? if it takes 100's of light years for that light to reach us, won't we in fact be looking at the past of that star, how do we know that that star is even there anymore? serious question, help...

Answer 1

Stupid question.I rather be eaten by sharks than to waste my time on you.

Answer 2

The most distant stars that we can see with the naked eye are a few thousand light-years away (let us say: 4,000).

Most of these are very luminous stars that use up their hydrogen very fast. Let us say that they will live a total of 4 million years before leaving the main sequence (it is actually much more than that, but let us just worry about the mathematics of the problem).

After that, they will live out the last stages of their lives very rapidly (red giant, blue giant, supernova, whatever). A "mere" million years.

Our Sun, by comparison, is a very weak star. If a twin to our sun was one hundred light years away, we would not see it (too faint). That is why we know most stars we see must be bigger.

So, if the average life of visible stars is 4 million years and their average distance is (let us say) 1,000 light years, then you could expect a probability of 1 in 4000 that a star is no longer there.

Since there are almost 8,000 stars visible to the naked eye, then I would expect that two stars we see are no longer there.

We already see stars that are now in their last stages, beyond their life on the main sequence. For example, Betelgeuse in Orion is already a red giant. We see it as it was 520 years ago, but its red giant phase will last much longer than 520 years, so, if we could instantly go there and look at it as it is now, we'd still see a red giant.

Answer 3

We don't. Every star out there could already be burnt out. However, we can observe conditions on our own sun which is only 8 minutes away at light speed and extrapolate that information to calculate the age and distance of other similar stars. There are also other types of stars that serve as 'benchmarks' for calulating distance and age of the star.

Answer 4

As a matter of fact, for the more distant objects being seen today (10+bln light years away) we can be reasonably certain they AREN'T still there! And, more annoyingly, there are certainly NEW things out there that we'll never know about because their light will take billions of years to arrive here.

We can only experience the brief snapshot of the universe that we get to observe and learn what we can from that snapshot.

Answer 5

We don't know, in fact the And. galaxy is more than 2 million light years away, we are seeing what it looked like more than 2 million years ago.

Answer 6

Yeah ur right we r not lookin at wat is actually there...