Although the stability of planetary motion helped Newton to establish the laws of classical mechanics, new research on the positions of the outer planets suggest they are governed by chaos. Norman Murray from the University of Toronto and Matthew Holman from the Harvard-Smithsonian Center for Astrophysics have developed a new analytical technique which reveals two chaotic resonance effects that could move asteroids and comets into the inner solar system. The resonances are caused by subtle gravitational interactions between Jupiter, Saturn, Uranus and Neptune (Science 283 1877).
Murray and Holman ran numerical simulations of the planets positions over a 200 million year period using their new technique. They discovered that although the outer planets appear in stable orbits, over longer time scales their classical ‘predicted’ orbit diverges from the simulations due to chaotic effects. One resonance is caused by interactions between Jupiter, Saturn, and Uranus. The second, weaker effect originates from the gravity wells of Saturn, Uranus, and Neptune. According to their calculations there is a 20 percent chance that the outer planets are now in a chaotic state.
