# Does rotation modify the effects of gravity,(does it flatten/narrow the curvature to the plane of rotation)?

As I have found, the major objects in space are orbiting around the center of gravity in a curved orbit that usually (more and more with time) matches the rotational plane of the central mass. So let's say a new planet would enter the solar system. Whatever direction it arrives from (most probably one that does not match the rotational plane of the Sun), first it will not orbit in the rotational plane of the Sun. But with time, it will converge to that rotational plane of the Sun. Questions:

1. Why is that? Does rotation of the central mass of gravity modify the gravitational effects actively? (Does it rotate the gravity field) Please note that I am asking here if the spacetime curvature gets modified by the rotation of the center of mass or not, so does curved spacetime look a little bit 'flatter' along the plane of rotation? (and so 'diverting' everything into the plane of rotation)
2. if the Sun would not be rotating, then the new planet that would arrive in the solar system would just keep orbiting in its own rotational plane (defined by what angle it came from)
3. the effects of gravity cause curved spacetime even without rotation? Have we seen a large non-rotating object in space that caused gravitational affects on its surroundings?

I'm pretty sure the current thinking is that the solar system started from the same cloud, and this cloud had an initial rotation. That rotation is the source of the rotational motion of the sun and the orbital motion of the planets.

I've never heard of a dynamical 3 body interaction where the angular momentum would tend to line up, but maybe...

If I were you, I would start by reading up on the formation of the solar system. The Wikipedia article on it https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System is pretty readable.

There are also some very nice documentaries around you should check out.

• thank you. But my question is more about if gravity is an active effect that changes with rotation or not. So what I have read is that the rotation of the center of mass aligns everything around it in this 2D plane. But I did not find anywhere exactly how gravity (spacetime curvature) does that. So i imagine that the gravitational effects (spacetime curvature) around a rotating center of mass must look a little bit flatter to the axis of the rotational plane, since bodies moving around the center tend to be pushed into the rotational plane, I guess but I am not sure HOW it works with GR. – Árpád Szendrei Oct 26 '16 at 18:53
• Actually I will change the title question based on that a little bit. – Árpád Szendrei Oct 26 '16 at 18:57
• There is a small effect, but it probably isn't big enough to do what you would like. – David Elm Oct 26 '16 at 20:19
• then what effect does it? – Árpád Szendrei Oct 26 '16 at 20:20
• There is an analogy between gravity and electricity/magnetism. There is a something a bit like a gravitational version of magnetism. en.wikipedia.org/wiki/Gravitoelectromagnetism Just as a spinning or rotating charge will produce a magnetic field, a spinning or rotating mass will produce a gravitational version of the magnetic field. – David Elm Oct 26 '16 at 20:22

Gravity and rotation are two counter forces relative to each other. If gravity of your new object is stronger than the gravity of the sun, it will in fact move the sun and would not converge. If gravity of this new object is less than that of the sun, then yes, it will converge. Think of it in simple term: F = M*A. Curved space-time is present regardless of rotation simply because your object is moving. (Although this could also be argued that any object that is moving is also in fact rotating according to the 5th dimension)

• ok, but why (how does it work with the curvature) will it follow the plane of rotation of the center of mass? will the curvature be flatter along the plane? It should be I guess cause what other effect would push the orbiting mass along the plane? – Árpád Szendrei Oct 26 '16 at 20:09