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No. 58: Jul-Aug 1988

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Chaotic Dynamics In The Solar System

The following abstract appeared in a 1988 issue of Eos, a weekly publication of the American Geophysical Union.

"Newton's equations have chaotic solutions as well as regular solutions. The solar system is generally perceived as evolving with clockwork regularity, yet there are several physical situations in the solar system where chaotic solutions of Newton's equations play an important role. There are physical examples of both chaotic rotation and chaotic orbital evolution.

"Saturn's satellite Hyperion is currently tumbling chaotically, its rotation and spin axis orientation undergo significant irregular variations on a time scale of only a couple of orbit periods. Many other satellites in the solar system have had chaotic rotations in the past. It is not possible to tidally evolve into a synchronous rotation without passing through a chaotic zone. For irregularly shaped satellites this chaotic zone is attitude-unstable and chaotic tumbling ensues. This episode of chaotic tumbling probably lasts on the order of the tidal despinning timescale. For example, the Martian satellites Phobos and Deimos tumbled before they were captured into synchronous rotation for a time interval on the order of 10 million years and 100 million years, respectively. This episode of chaotic tumbling could have had a significant effect on the orbital histories of these satellites."

Theis abstract continues, naming as other candidates for chaotic histories: some of the asteroids, Miranda (a satellite of Uranus), and the planet Pluto. (Wisdom, J.; "Chaotic Dynamics in the Solar System," Eos, 69:300, 1988. Also see: Kerr, Richard A.; "Pluto's Orbital Motion Looks Chaotic," Science, 240: 986, 1988.)

Comment. We have been assured often, particularly in the days of Velikovsky, that the solar system has been stable for billions of years! Yet, Wisdom states very clearly above that synchrony cannot be evolved without passing through a chaotic zone. The solar system abounds in resonances, not the least of which is the earth-Venus resonance. For more on this, see ABB1 in our catalog: The Sun and Solar System Debris. This volume is described here.

From Science Frontiers #58, JUL-AUG 1988. � 1988-2000 William R. Corliss