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# Is the earth pulled around by the moon?

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This seems like a no-brainer, but does the earth's distance from the sun fluctuate due to the moon's pull? In other words, does the moon completely orbit the earth, or does the earth do a little bit of moving as well?

To give an example, if you tie a string between two masses and spin them in the air, the bigger mass will still move around a little bit, even if the other mass is a fraction of the size.

If so, how much does the earth's orbit fluctuate?

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what youre thinking makes sense, newton 3rd law

I think earth doesn't move around moon because of inertia. The moon does pull on earth but not enough to make it start moving.

keep in mind that im likely to be wrong

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The moon doesn't orbit the earth. The moon and earth both orbit a center of mass of the system.

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YD is right. In case you want more explanation, here's a good place to start:

http://en.wikipedia.org/wiki/Orbit_of_the_Moon

If you have new questions after reading, post again.

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Iv got a question thats been bugging me for a while, when its a full moon in the UK for example, is it a no-moon or half moon somewhere else on the planet?

a bit like Eclipses can occur in one area but not in another.

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no, but half the planet will be unable to see the moon due to the earth. but that half of the planet will be in daylight anyway.

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Iv got a question thats been bugging me for a while, when its a full moon in the UK for example, is it a no-moon or half moon somewhere else on the planet?

a bit like Eclipses can occur in one area but not in another.

No. It's e.g. a full moon because the moon is on the far side of the earth, and is fully illuminated by the sun. The earth is just rotating, letting us all see that. I think if you drew a picture you'd see this.

———

You can see the effect of the moon's effect on the earth, making the orbit "wobble," by looking at the time of aphelion and perihelion. Unlike the solstices and equinoxes, which basically advance 6 hours and then reset on a leap year (reflecting the extra ~.25 day in the year), the time of the aphelion and perihelion jump around, because the moon's orbit isn't synched up with the length of the year, and the location of the moon affects the distance to the sun.

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so if its a full moon in the UK its a full moon everywhere, it may just take 12 hours for someone in america to see it.

Thanks

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Thanks for the help. I thought the moon and earth had an off-centered center of gravity.

I have another question, though: How does the moon keep the earth's axis rotation stable? Apparently, if we didn't have the moon, we would have almost a 90 degree turn every season. How does the moon stop this?

And thanks again for the help!

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The center of gravity between the Moon and Earth is not at Earth's exact core but it is somewhere in the mantle. So Earth has a wobble.

Some stars have significant wobbles produced by their planet(s?). This was astronomer's first clue towards the discovery of these extrasolar planets.

As far as our own Sun. I don't know what type of wobble it would have considering it doesn't have but one measely planet like many other "solar systems" out there. Since there are 7 other planets, et. al. It surely is a complex influence on the sun itself.

Earth also has a wobble in it's rotation.

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I have another question, though: How does the moon keep the earth's axis rotation stable? Apparently, if we didn't have the moon, we would have almost a 90 degree turn every season. How does the moon stop this?

Not every season — over a long time. The earth precesses, but having the moon limits the excursion.

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The earth and moon orbit around a center point in space called the La grange point where gravity is equal between the earth and moon.

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Somewhat, because both the earth and the moon are so large their gravitational fields affect eachother, this interference can easily be seen in tides for instance.

The gravity of the mooon is strong enough to pull the tides to oneside or the other, this is seen as low tide and high tide. our earth has a similar effect on the moon, but there is no water or oceans to see such effects.

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The earth and moon orbit around a center point in space called the La grange point where gravity is equal between the earth and moon.

No.

The Earth and Moon orbit about their center of mass, the position of which is inside the Earth (as has been previously noted). The Earth and Moon do not orbit any the Lagrange points (also called Lagrangian points and libration points). There five such points, none of which is located at the point "where gravity is equal between the earth and moon". The Lagrange points are points of equilibrium in the "circular restricted three body problem".

One of the Earth-Moon Lagrange points, L1, is located between the Earth and the Moon, but it is a bit closer to the Earth than is the "point where gravity is equal between the earth and moon". This latter point is of very little interest. Both the L1 point and this neutral point are located a lot closer to the Moon than they are to the Earth.

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Your right. It refers to a third mass such as a spaceship.Where at this point it would need very little fuel to sustain its position. A Lagrange point is a point in a system of two celestial bodies that orbit their common center of gravity in circular orbits, in which a space ship or other thing of negligible mass can remain for a long time without needing propulsion. Such a system of two bodies in circular orbits has five Lagrange points. And the other half looks good too. So my statment is only half right. The mind is the first thing to go.

lagrange points →

No.

The Earth and Moon orbit about their center of mass, the position of which is inside the Earth (as has been previously noted). The Earth and Moon do not orbit any the Lagrange points (also called Lagrangian points and libration points). There five such points, none of which is located at the point "where gravity is equal between the earth and moon". The Lagrange points are points of equilibrium in the "circular restricted three body problem".

One of the Earth-Moon Lagrange points, L1, is located between the Earth and the Moon, but it is a bit closer to the Earth than is the "point where gravity is equal between the earth and moon". This latter point is of very little interest. Both the L1 point and this neutral point are located a lot closer to the Moon than they are to the Earth.

A Lagrange point is a point in a system of two celestial bodies that orbit their common center of gravity in circular orbits, in which a space ship or other thing of negligible mass can remain for a long time without needing propulsion. Such a system of two bodies in circular orbits has five Lagrange points.

lagrange points →

Edited by interstellar
multiple post merged

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