Mean Orbital Separation Question

AI Thread Summary
Orbital separation refers to the average distance between a planet and its moon during their orbit. To calculate it, one can use the orbital period formula, which can be rearranged to solve for the semi-major axis, representing the mean orbital separation. In the given scenario, a moon with a mass of 0.5 times Pluto orbits a planet with a mass of 2 times Pluto, resulting in a total system mass of 2.5 times Pluto. Resources like orbit simulators can assist in performing the necessary calculations. Understanding these concepts is crucial for accurately determining orbital dynamics.
hulkster1988
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So it was basic to figure out the masses and such, but I'm not exactly sure what the "orbital separation" really is? Can someone enlighten me? Here is the question for reference:

A moon with a mass one quarter that of its parent planet orbits that
planet with a period of 12 days. The mass of the planet is twice that of
Pluto. What is the mean orbital separation of the planet and its moon?

Thanks for any help.
 
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planet = 2Pluto
moon = .25 * 2Pluto = 0.5Pluto
total system mass = 2.5 Pluto

Google for Pluto's mass

Once you have it, you can algebraically re-write the Period formula P=2pi*sqrt(a3)/GM) to solve for a, the semi-major axis, which should equal to your orbital separation in a circular orbit, or your average orbital distance when averaged over longitude rather than time. There's a couple of calculators on this page: http://orbitsimulator.com/formulas/ that will do it for you. The 3rd one is the Period formula, and the 4th one is this formula re-written to solve for "a".
 
Great, thanks a lot ...that link is very helpful
 
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