SOLAR-SYSTEM CHAOS AND THE DISTRIBUTION OF ASTEROID ORBITS

We describe results from numerical simulations to follow the orbits of hundreds of test particles that originate from low-inclination orbits in the terrestrial domain, in a model of the Solar system which inclu des all major planets. Our 3-Myr integration shows that a general feat ure of the asteroidal trajectories is a large Liapunov exponent, i.e. the orbits are chaotic with an astronomically short e-folding time for deviations. An exception to this is the region in which the real aste roids are found. Our computations also explain the low number of aster oids in the interplanetary region of the terrestrial planets. We confi rm the results of other investigators concerning the Liapunov exponent of the Solar system itself: from a 200-Myr integration of the entire Solar system, an e-folding time of about 6 Myr is obtained.