To answer your last post; As a geocentrist I don't attribute the Solar System's activity to gravity; first because gravity just can't explain it, and secondly because as a Christian I believe that God set the entire Solar System in the order he wanted it in.
"When I consider thy heavens, the work of thy fingers, the moon and the stars, which thou hast ordained; What is man, that thou art mindful of him? and the son of man, that thou visitest him?" -- Psalms 8:3-4
There are many other natural explanations (i.e. Electric Universe...); read some of the sites I linked to in my first post....they deal with that a bit