2007-05-15 01:19:45 · 4 answers · asked by Bryant A 2 in Science & Mathematics ➔ Astronomy & Space
By observing objects billions of light years away, they can see what those objects looked like billions of years ago.
2007-05-15 01:23:45 · answer #1 · answered by Darth Vader 6 · 0⤊ 0⤋
They observe distant objects. The speed of light is theoretically the greatest velocity that anything in the universe can have, but it's still finite. We measure large astronomical distances in terms of how long it takes light to travel those distances. A light year is the distance light travels in a year. So if an object is a thousand light years away, like some stars within our own Milky Way galaxy, it means that when we are observing it, the light we see left the star a thousand years ago. We are seeing the star as it appeared a thousand years ago. If the star exploded in a supernova two hundred years ago, we wouldn't see that for another eight hundred years. So when astronomers observe very distant objects, billions of light years away, they are seeing how that object looked billions of years ago. Therefore, observing extremely distant objects shows scientists how parts of the universe looked in the extremely distant past.
2007-05-15 08:21:58 · answer #2 · answered by DavidK93 7 · 0⤊ 0⤋
You Look In The Past Measured In Light Years From Us.
2007-05-15 08:31:21 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Very carefully...and they always check twice!
Now, Astronomers check their theories looking at lots and lots of charts, I'm sure!
2007-05-15 08:52:39 · answer #4 · answered by canguroargentino 4 · 0⤊ 0⤋