How Did Roemer Measure the Speed of Light Using Jupiter's Moons?

AI Thread Summary
Roemer measured the speed of light by observing the delays in the eclipses of Jupiter's moon Io, noting a 22-minute delay as Earth moved from its closest to farthest point from Jupiter. This observation led to a calculation involving the average radius of Earth's orbit, approximately 1.50 x 10^8 kilometers. The key to determining the speed of light lies in understanding the additional distance light must travel when Earth is at its farthest point from Jupiter. To calculate the speed of light, one must consider the difference in distance and the time delay observed. This method provided one of the first empirical estimates of the speed of light.
dekoi
As a result of his observations, Roemer concluded that eclipses of Io by Jupiter were delayed by 22 min during a 6 month period as the Earth moved from the point in its orbit where it is closest to Jupiter to the diametrically opposite point where is is farthest from Jupiter. Using 1.50 x 10^8 as the average radius of the Earth's orbit around the Sun, calculate the speed of light from these data.
I have absolutely no idea how to start this. Please give me some suggestions.
Thank you.
 
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First ask yourself how much further the light has to travel when the Earth is furthest away from Jupiter compared to when it was closest to Jupiter. (Note that your value for the average radius of the Earth's orbit around the sun is given in kilometres)
 

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