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Home Q & A Board Science-Related Homework Help Physics
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killian killian
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10 years ago
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) it 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
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padrepadre
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10 years ago
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killian Author
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#2
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10 years ago
Thx man
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