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Measuring speed of light

  1. Dec 6, 2013 #1
    I know about the Michaelson-Morley expt. trying to measure the speed of light, once in the direction of motion of the earth and then perpendicular to it. But the source of light was a torch (or similar) which is (obviously) on earth.

    I have somewhere read that it was also done with the source of light as sun. That is, it was experimented to find out whether the speed of light from sun appears the same while moving towards it or away from it. Can anyone tell me more about this experiment (with respect to sun) or provide a reference giving more details?
  2. jcsd
  3. Dec 6, 2013 #2


    Staff: Mentor

    In the wiki article:


    Check the section on 'Astronomical Measurements'

    They use a telescope and study moons of other planets as we are approaching an receding from them.
  4. Dec 7, 2013 #3


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    Science Advisor
    Gold Member

    MMX was not actually measuring the speed of light, it was comparing the round-trip speed of light along one path to the round-trip speed of light along a perpendicular path.

    I think you may be remembering the DeSitter experiment which compared the one-way speed of light between two stars
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