Multiple Choice
If we say that a galaxy has a lookback time of 1 billion years,we mean that
A) its light traveled through space for 1 billion years to reach us.
B) is now 1 billion light-years away.
C) it was 1 billion light-years away when the light left the galaxy.
D) it is 400 million years old.
Correct Answer:
Verified
Correct Answer:
Verified
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