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kyt_0903
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I am doing a project about the earth, the sun, and the moon. My question is why does the moon rotate around the earth?
russ_watters said:Welcome to PF.
That's a little bit of a vague question...what would happen if it didn't?
Borek said:The shortest answer (and probably not the one you expect) is: it doesn't
why?Borek said:The shortest answer (and probably not the one you expect) is: it doesn't
kyt_0903 said:
kyt_0903 said:why?
But why does it go around the earth?Jonathan Scott said:I'm guessing that what Borek means is that from the point of view of someone at rest in the Solar System, the Earth and Moon orbit together around the sun, but their orbits wiggle slightly around each other because of their mutual gravitational pull. The orbit of the moon around the sun is always curved towards the sun, so from that point of view it would be difficult to see the moon as going around the earth.
However, from the point of view of the earth, the moon rotates about the earth. In fact, the Earth and moon together orbit their common center of mass, but because the Earth is so much heavier, that's approximately the same as the moon going round the earth.
The general answer is that because moon is passing fairly close to the earth, the Earth's gravity pulls it round into a closed orbit, and the smoothing effect of tides over millions of years have made that orbit approximately circular and the moon's rotation to synchronize with the orbit so that it always presents approximately the same face.
yeahBorek said:I was aiming at the fact that both Earth and Moon rotate around barycenter. It happens that the barycenter is inside the Earth, but quite far from the Earth center.
Have you heard about momentum conservation?
kyt_0903 said:yeahBorek said:Have you heard about momentum conservation?
I thought you were aiming for the fact that the Moon revolves, with rotation being used for a single object about an axis.Borek said:I was aiming at the fact that both Earth and Moon rotate around barycenter...
tony873004 said:I thought you were aiming for the fact that the Moon revolves, with rotation being used for a single object about an axis.
That is a good point of distinction, and one not asked of the original poster.tony873004 said:I thought you were aiming for the fact that the Moon revolves, with rotation being used for a single object about an axis.
kyt_0903 said:But why does it go around the earth?
The Moon rotates around the Earth due to the force of gravity. The Earth's gravity pulls the Moon towards it, causing it to orbit around the Earth.
Yes, the Moon rotates around the Earth at a constant speed. This is because of the laws of physics, specifically the law of conservation of angular momentum.
The Moon takes approximately 27.3 days to complete one rotation around the Earth. This is known as its orbital period.
No, the Moon's orbit around the Earth is not perfectly circular. It is slightly elliptical, meaning there are times when the Moon is closer or farther from the Earth during its orbit.
Yes, the Moon does rotate on its own axis as it orbits the Earth. This is why we always see the same side of the Moon facing us from Earth.