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Distance and age

  1. Sep 11, 2010 #1
    I thought i understood a light year as a measure of distance.But i keep running into articles that say something like ....around Galaxy NCG 4921 there are a cluster of galaxies estimated to be 13+ billion years old at a distance of 320 light years from earth.How do you get that when you are measuring red shifts?
    Or how do you get "there are globular clusters that appear older than the known universe?"
    Thank you for any help.:confused:
  2. jcsd
  3. Sep 11, 2010 #2


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  4. Sep 11, 2010 #3


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    Redshift limits the maximum age of objects in the universe. That is to say that a galaxy 13 billion years old cannot be at a redshift distance in excess of about 700 million light years. Similarly, a galaxy 6 billion light years distant cannot be more than about 7.7 billion years old. So NGC 4921 at a distance of 260 million light years could be 13.4 billion years old.
  5. Sep 14, 2010 #4
    Re: Distance and age/I think i have it!

    By George,I think i have it.Thank you mothman and Chronos.
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