Astronomy - Orbit length and Oribital Period of the moon to Mass of the Larger planet

1. Sep 15, 2008

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This question has been stumping me on my Astronomy homework for the past couple of days. I've tried to input the question into any of the other formulae that we've studied, but I keep drawing a blank on it.

1. The problem statement, all variables and given/known data

Given the size of Triton's orbit(a = 355,000,000 meters) and its orbital period (P = 5.877 days), calculate the mass of Neptune.

2. Sep 15, 2008

mgb_phys

Re: Astronomy - Orbit length and Oribital Period of the moon to Mass of the Larger pl

Look up kepler's third law, it does include the mass of the moon but as long as this is much less than the mass of the planet it can be ignored.

Last edited: Sep 15, 2008
3. Sep 15, 2008

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Re: Astronomy - Orbit length and Oribital Period of the moon to Mass of the Larger pl

Thanks.