This is very intriguing...after learning the basics of Kepler and others mentioned above ... I have been under the impression that "chaotic" models have also been mentioned as possible models that could better explain the motion of the starry wanderers.

see:
Chaotic Motion in the Solar System

Rev Mod Phys
Volume: 71
Year 1999
page: 835

Author: Jack J. Lissauer

__________________
"The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir."
---Carl Sagan