Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case, .
A)Galaxy 1 must be twice as big as Galaxy 2
B)Galaxy 2 must be twice as old as Galaxy 1
C)we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2
D)we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2

Question

Quizplus · Accepted Answer

When we observe distant galaxies, we are actually looking back in time because the light takes time to reach us. So, since Galaxy 1 is farther away, we are seeing it as it looked at an earlier time in the history of the universe than we are seeing Galaxy 2. Therefore, option D is the best choice. There is no direct relation between the distance of a galaxy and its size or age, so options A and B are incorrect. Option C does not make sense as we cannot determine the exact time at which a galaxy was formed just by looking at it.

Suppose We Look at Two Distant Galaxies: Galaxy 1 Is