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L.W. Esposito (LASP - Univ. of Colorado)
Key aspects of our current understanding of planetary rings are that rings are young and invariably found intermixed with small moons. These characteristics highlight the importance of random events in explaining their history and morphology. Rings arise from singular events like the destruction of a ringmoon or comet. Many of their striking visual characteristics are the result of transient phenomena: ring arcs, bright clumps, spokes, microsignature absorptions. A ring’s physical nature is the result of a competition between fragmentation and accretion in the planet’s Roche zone. These processes often involve occasional major events. Some recent results of considering random processes include the natural coexistence of rinmoons and rings in the Roche zone; explanation of the photometry, spectrum, and dust in Saturn’s G ring, with implications for the safety of Cassini; how charge fluctuations in Jupiter’s ring may explain rapid evolution and longitudinal variations; that Neptune’s ring arcs are transient, but repeatedly renewed; and how a belt of moonlets between Prometheus and Pandora can explain both the bright clumps occasionally seen and the changes in the so-called ‘shepherds’ orbits (not to mention the recent advent of ring F, itself). Ring history is disorderly. These stochastic phenomena require long term observations to see individual events and to track the system responses. Cassini is now planning imaging movies, spectroscopy, and multiple stellar and radio ring occultations from Saturn orbit; and movies, phase curves, and ring plane crossing observations of the Jovian ring during its Jupiter flyby in 2000.
The author(s) of this abstract have provided an email address for comments about the abstract: esposito@maia.Colorado.EDU