When we look at the stars, are we actually staring into the past?

Question

Some stars are 20 billion light years away...so in fact the light we see when we look up at the stars actually took 20 billion years to reach our eyes...wouldn't that mean that the star could of blown up 10 billion years ago and we would still see it as it is?

Answer 1

you would see it as it was a long time ago

Answer 2

Yes. But you are looking into the past any time you look at anything! You are looking 9 years into the past when you look at the star Sirius, you are looking 8 minutes into the past when you look at the Sun, you are looking about a second and a half into the past when you look at the Moon and you are looking a small fraction of a second into the past when you look at your computer screen.

Answer 3

eerie how huge the universe is, isn't it....reminds me of cake....and of course 42....god i love the hitchhikers guide to the galaxy

Answer 4

no. light years are a measure of distance not time. 1 light year is how far light would travel in a year *exactly 9,460,730,472,580.8 km*.

so no, your not looking into the past, your look at a sun:18,921,460,945,161,600,000,000,000 km away

Answer 5

That's true. We're seeing what that star looked like at some point in the past.  Alpha Centauri, the closest star besides the sun, is 4.3 light years away;  if something happened to it in the last 3 years, we wouldn't know about it for another 16 months.  

Answer 6

20 billion light years away you'll find other galaxies which have their own stars.  Our galaxy which is a collection of some 100 to 300 billion stars has a diameter of 100,000 light years.  In a dark sky, most stars you see are relatively close to us. All individual stars that you can see with the naked eye are within 4000 light years and most are well closer than that.  

Since light from any object has to travel to us for us to see,  the farthest stars at a little over 4000 light years, that light has taken 4000 years to reach us so we are actually seeing those stars as they were 4000 years ago.  The farthest galaxies we can see are 13 billion light years away so we are seeing those galaxies as they were 13 billion years ago.  

In essence, a telescope is a time machine that can see the universe into the long ago past.  We can actually watch the universe age when we look at galaxies at different distances.

Answer 7

Um. Yea. wow your absoultly right. good job. nerd. lol jk jk

Answer 8

Yep, you are entirely correct!  The Andromeda Galaxy, or m31 is, in fact, 2 million light years away and what we're seeing now happened 2 million light years ago.  Astronomers and other scientists are now looking closely at a couple of stars that are threatening to explode at any time.  

One is Betelgeuse, a giant red star that is in the constellation Orion.  Since it is so close, people are keeping a close eye on it, every night.  They are afraid it will explode as a gamma ray burst, that will threaten life on Earth, due directly to the gamma rays that will be released.  Gamma Rays are "bad" for ones DNA.      

Answer 9

ya isn't it amazing!! :) i love thinking about that stuff

Answer 10

that is true, that is also wat explains a shooting star. When you see a shooting star, it means that this star could have been dead for an extremely long time and we are just seeing it die for the first time on earth. We are actually watching the stream of light end.