A galaxy is at a distance of one billion light-years. Which of the following is true?
A)We see the galaxy the way it will be in one billion years.
B)We see the galaxy the way it was one billion years ago.
C)We see the galaxy the way it was when the universe was one billion years old.
D)We see what our galaxy will be like in one billion years.
E)We have no knowledge of anything at that distance.

Question

Quizplus · Accepted Answer

Since light from the galaxy has taken one billion years to reach us, we are seeing the galaxy as it was one billion years ago. Since light takes time to travel to us, the light we are receiving from the galaxy left it one billion years ago. Therefore, we are seeing the galaxy the way it was one billion years ago.

A Galaxy Is at a Distance of One Billion Light-Years