# Planar orbit of planets around sun

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Imagine thee planets interacting through gravity, mathematically how should they come and rotate in a same plane, like planets and sun?

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A.T.
Imagine thee planets interacting through gravity, mathematically how should they come and rotate in a same plane, like planets and sun?

Dale
Staff Emeritus
2019 Award
Three points determine a plane.

sir i heard all that the galaxies started as dust and then it cooled and due to angular momentum conservation it happrnd, but my question is that if three point masses are interacting can you give me an equation that tells that they will eventually rotate in a single plane?

Three points determine a plane.
but rotation can be in two planes, think about it, a point fixed at origin second point rotating aroung it in xy plane and third one in yz plane.

A.T.
sir i heard all that the galaxies started as dust and then it cooled and due to angular momentum conservation it happrnd, but my question is that if three point masses
It applies to 3 particles too, but collisions are less likely.

A.T.
Three points determine a plane.
I think the OP means a plane that contains the Sun too, and has a fixed orientation in an inertial frame.

Staff Emeritus
2019 Award

Three points determine a plane. Three bodies will always be in a plane. It is true that that plane may not be constant in a particular coordinate system (e.g. one where everything is moving up with some velocity) but that is always true.

If you are talking about three planets and the sun, you should say so and do it clearly.

Tyrannosaurus_

Three points determine a plane. Three bodies will always be in a plane. It is true that that plane may not be constant in a particular coordinate system (e.g. one where everything is moving up with some velocity) but that is always true.

If you are talking about three planets and the sun, you should say so and do it clearly.

I chose three points just to make the problem simpler you can aslo say it for four points they dont lie in a plane nessesarily but thry come in a plane if interacting through a central force

It applies to 3 particles too, but collisions are less likely.
So they dont come into a place throught collisions ..sp how do they come in the plane?

So they dont come into a place throught collisions ..sp how do they come in the plane?
I mean three particles..if collisions are less likely ..let say one has radius of orbit twise as big than the other and they rotate around sun with sun at center in circular orbits...and their axis of rotation are perpendicular..will they cone to an intermediate plane?

No.
so the collisions is the only culprit here? or can we say they come into plane through mutual graviational attraction?

A.T.
I mean three particles..if collisions are less likely ..let say one has radius of orbit twise as big than the other and they rotate around sun with sun at center in circular orbits...and their axis of rotation are perpendicular..will they cone to an intermediate plane?
Without collisions, they won't necessarily tend towards one plane.