Chaotic Orbits and Spins in the Solar System

It was surely the intricate clockwork regularity of the solar system, as our ancestors observed and pondered it over millenia, that inspired the quest that culminated in the differential equations of Isaac Newton. It is somewhat ironic, therefore, that these same differential equations—usually regarded as epitomizing order and predictabilty—also appear to be generating chaos in the solar system. Nowadays, when one speaks of chaos, especially in an essentially conservative, Hamiltonian system like the solar system, one does not mean the unpredictability inherent in intrinsically disorderly phenomena such as thermal noise or innumerable random collisions. The modern study of chaos (PHYSICS TODAY, December 1983, page 46) deals with the onset of wild and unpredictable fluctuations in systems governed by simple, deterministic equations from which one would naively expect nothing but good behavior.

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