Possible Duplicate:
Why are our planets in the solar system all on the same disc/plane/layer?
I've noticed this in many pictures, Planets are shown with a single ring around them (in some particular plane). Taking extreme case... As gravity should act in all the directions, such planets must be covered with asteroids all around them. Not just single ring in some single plane..!
So, My question is: Why don't planets have many rings instead of just a single ring..?
Because of the rotation of the planet. E.g. Our galaxy rotates so it has also a stubble elliptical appearance. It is the same with planets orbiting sun but on a larger scale. Btw. if the planet did not rotate at all (which is in reality impossible in space) the rocks/ring material would be distributed "everywhere equally". However, it is impossible in real space, where everything is rotating in some way because of other forces of larger objects and the material must come from somewhere to the planet etc.
