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) we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2
C) we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2
D) Galaxy 2 must be twice as old as Galaxy 1

Question

Quizplus · Accepted Answer

When we look at distant galaxies, we are seeing them as they were in the past because it takes time for their light to travel to us. Since Galaxy 1 is twice as far away, it means its light took twice as long to reach us, so we are seeing it as it appeared in the past. Therefore, option B is the correct answer. Option A is incorrect because the distance between galaxies does not necessarily determine their size. Option C is also incorrect because, as stated above, we are actually seeing Galaxy 1 as it appeared in the past. Option D is unrelated to the question and therefore incorrect.

Suppose We Look at Two Distant Galaxies: Galaxy 1 Is