Why does the light travel at precisely the speed...

[lemur]

http://en.wikipedia....ght#Measurement

 

That includes three different astronomical methods. The simplest, now that we have space probes all over the solar system, is to simply time a signal between them.

Thanks for posting these links. With the method that measures the difference in orbital periods of the moons, I wonder how they established a complete revolution if the orientation of the Earth from Jupiter was changing due to their respective orbital movements. I still don't understand exactly the method that looks at how the stars move relative to the Earth's position but I did notice that the number of minutes for light to cross the full diameter of Earth's orbit was 22 minutes, which is more than 2X the 8 minutes it supposedly takes for light to arrive from the sun; but is the additional time due to the diameter of the sun itself maybe? Also, although I can see how these discrepancies are measured in terms of minutes measured on Earth, I'm not sure what the basis is for measuring the distances in question. Is it just Newton's inverse square formula and assumptions about the relative masses of the bodies based on estimates?

[swansont]

Thanks for posting these links. With the method that measures the difference in orbital periods of the moons, I wonder how they established a complete revolution if the orientation of the Earth from Jupiter was changing due to their respective orbital movements. I still don't understand exactly the method that looks at how the stars move relative to the Earth's position but I did notice that the number of minutes for light to cross the full diameter of Earth's orbit was 22 minutes, which is more than 2X the 8 minutes it supposedly takes for light to arrive from the sun; but is the additional time due to the diameter of the sun itself maybe? Also, although I can see how these discrepancies are measured in terms of minutes measured on Earth, I'm not sure what the basis is for measuring the distances in question. Is it just Newton's inverse square formula and assumptions about the relative masses of the bodies based on estimates?

 

I think it has more to do with the experiment taking place in 1676 and was experimental error.