Does the Speed of Light Change When Measured from the Sun?

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SUMMARY

The discussion centers on the measurement of the speed of light, specifically in relation to experiments involving the Sun as a light source. The Michelson-Morley experiment (MMX) is highlighted for its role in comparing the round-trip speed of light along different paths, rather than directly measuring its speed. The DeSitter experiment is also mentioned, which focused on the one-way speed of light between two stars. These experiments contribute to the understanding of light speed in varying contexts, particularly in astronomical measurements.

PREREQUISITES
  • Understanding of the Michelson-Morley experiment (MMX)
  • Familiarity with the DeSitter experiment and its methodology
  • Knowledge of astronomical measurements and their significance
  • Basic principles of light speed and relativity
NEXT STEPS
  • Research the detailed methodology of the Michelson-Morley experiment (MMX)
  • Explore the DeSitter experiment and its implications for one-way light speed
  • Study the section on 'Astronomical Measurements' in the Wikipedia article on speed of light
  • Investigate the effects of relative motion on light speed as described in relativity theory
USEFUL FOR

Astronomers, physicists, students of relativity, and anyone interested in the fundamental principles of light speed and its measurement in various contexts.

rushikesh
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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?
 
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rushikesh said:
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.
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.

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

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