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Andrew Mason
Mar7-11, 08:32 PM
Sci Advisor
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Quote Quote by atomqwerty View Post
(*)The difference would be that while a sideral day is completed in 23h56'4", a solar day needs 24h to be completed, this is, 3'56" aprox.
Can you show how this is calculated? What is the exact angle that the earth moves through in one solar day, assuming a circular motion? (how is this related to the average angle per solar day for an elliptical motion?).

This difference can't be constant, because of earth's orbital velocity, that changes along the year.
With Kepler's 2nd Law, we can write the angular velocity L=mrv=mr'v' as a constant, where m is tha Earth's mass, r and r' represent the radiovector sun-earth in two given days. I could use the ellipse formula to give an expression for the time between two given days, keeping in mind (*). Am I in the correct way?
You might be. How is the angle that the earth travels through in a solar day related to the earth's distance from the sun? How much does this distance vary through out the year? How much does the angle vary? How much time does this variation represent?