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Title: If we say that a galaxy has a lookback time of 1 billion years, we mean that ___ Post by: killian on Apr 30, 2014 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 Title: Re: If we say that a galaxy has a lookback time of 1 billion years, we mean that ___ Post by: padre on May 3, 2014 Content hidden
Title: Re: If we say that a galaxy has a lookback time of 1 billion years, we mean that ___ Post by: killian on May 3, 2014 Thx man
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