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Earth Orbit?

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#1 Brian Albin

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Posted 30 December 2012 - 07:51 PM

I have read that while Earth’s Moon orbits around the Earth, a more precise understanding is that Earth and it’s Moon each orbit around a shared point somewhere between the centers of the two bodies. In this case the point is so much closer to the center of Earth than to the center of the Moon that it is inside the globe of the Earth. The Moon goes once around this point in a month. How long does it take the center of the Earth to make an orbit around this point?

#2 GlennLeDrew

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Posted 30 December 2012 - 07:55 PM

The same period as for the Moon--both bodies' center of mass lie on opposite sides of the barycenter of the system.

#3 Brian Albin

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Posted 30 December 2012 - 07:56 PM

Thanks, Glenn.

#4 Qwickdraw

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Posted 31 December 2012 - 04:26 PM

Here is a very good explanation of the physics of it.

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