Re: Why Sun and the planets are in the same plane?
Why the planets in the solar system are in same plane with the Sun?
Here’s wikipedia’s article on it, and below is my somewhat more sloppy explanation.http://en.wikipedia.org/wiki/Formation_ ... lar_System
Ok, so what happens is you start off with a big cloud of elemental dust called a nebula. The nebula that the sun came from was the remains of some probably second generation star going supernova.
The particles in the cloud attract eachother gravitationally. I’ve heard some rumbling that another supernova nearby may have kickstarted the process that got our nebula coalescing, but at any rate, particles begin to travel toward eachother, but they don’t all just fall strait in. They will have their own inertia from whatever circumstances they came from, and so one particle goes to move toward another, but ends up trailing it a bit.
The net motion of all these particles coming together, and chasing the motion of the particles they are gravitating toward begins a vortex motion. The conservation of angular momentum (retaining spin, essentially) means that the overall motion of the nebula will be in the direction of the most particle’s initial inertia.
Where particles are building up as they collect together causes an even stronger pull on those particles which are not yet a part of the grouped particles, producing a stronger gravitational pull toward those particles, and clearing out the regions “above” and “below” the angular plane of rotation of the cloud.
So, gravity pulls all the particles together, the particles continue moving with their initial inertia, plus the pull of gravity, causing them to circle in toward the center, which pulls the less influential clumps of matter into line behind them.
Clumps grow larger and large, becoming more gravitationally dominant and bigger and rounder all the time. They form asteroids, and planets and many of these have the wrong momentum to maintain a stable orbit around the cloud. These either fall into the center, or shoot off into space, or are arranged in wonky elliptical orbits which will ultimately bring them into conflict with another orbiting body, causing a collision.
So much matter (most of it hydrogen) collects in the center that thermo-nuclear-fusion begins, and the star lights up.
Most planets are also spinning in the same direction as the spin of the solar system, and this too owes to conservation of angular momentum. It’s the same process, but on a smaller scale.
So essentially the particles fall in a plane due to the momentum of gravitationally dominant particles, or masses, pulling the others behind, the sun is more or less at the center, and everything else falls into a plane because it is all balancing against itself. The things which would not stay in a stable orbit have been ejected from the system, or absorbed into dominant massive objects.