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Math Help - light years and wave equation

  1. #1
    Junior Member
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    light years and wave equation

    If we see the light coming from a galaxy 100 light years away, how long ago was the light emitted?
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  2. #2
    Super Member
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    the galaxy is 100 light years away, that means the takes 100 years for light to travel that distance, so the light was emitted 100 years ago.


    Bobak
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