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Author Topic: Shape of the moon's orbit  (Read 1636 times)

Offline ruthW

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Shape of the moon's orbit
« on: 30/06/2009 14:10:40 »
My daughter asked me a question that I could not answer today.  What is the shape of the moon's orbit round earth?  Is it  circular,oval  or wavy circle (sorry can not think of another way to describe it) due to the gravitation pull of the sun esp when the moon is between the earth and the sun?    This is really rough as I am not good with the pencil and free drawing but I hope that it gives you some idea of the "wavy circle"


 

Offline LeeE

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Shape of the moon's orbit
« Reply #1 on: 30/06/2009 17:50:52 »
Hmm...  fried egg with a slice of lemon and a pea.

The Moon's orbit around the Earth is very nearly circular; it has an orbital eccentricity of just 0.0549.  The Moon's orbit around the Sun will be more wobbly though, and closer to your fried egg.
 

Offline Bored chemist

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Shape of the moon's orbit
« Reply #2 on: 30/06/2009 18:41:37 »
The moon's orbit round the sun looks like a 13 sided polygon with rounded corners.
 

lyner

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Shape of the moon's orbit
« Reply #3 on: 01/07/2009 15:48:55 »
Yes -  no cusps, in the case of the Moon; it is always traveling in the same orbital direction.
Earth's speed through space is about 30km/s and the Moon is 'only' traveling backwards at about 17m/s [edit - typing!!] when it is on the Sun side of Earth.

I think this must be a general situation, when you have a single, massive, central object and smaller objects, with their moons, orbiting around it. You might get loops in binary star systems, where the poor old satellite wouldn't know which star it was supposed to be orbiting around. I think that would not be stable.

But, it's all relative. In the old days, when they thought the Sun orbited 'around the Earth', people saw Mars's orbit and said that it had a loop in it -and it did - relative to Earth.
« Last Edit: 01/07/2009 18:04:50 by sophiecentaur »
 

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Shape of the moon's orbit
« Reply #3 on: 01/07/2009 15:48:55 »

 

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