IGPP Seminar Series

History of Saturn's Rings

by Dr. Larry Esposito
University of Colorado

Abstract

The close-up Cassini observations of Saturn's rings show amazing variability and activity: numerous kinks, bright patches, braids, interchanges between rings and moons, clumps in the Encke gap, a small moon in the Keeler gap, waves, wakes, a variable cloud of neutral oxygen, a low surface mass density for the Cassini Division, sporadic EM bursts, sharp edges, short-range compositional gradients, fresh ice at density wave locations, and both counting statistics and time variability that indicate short-lived clumps in Saturn's A ring.

This dynamic present state implies an equally active past. Such processes would rapidly deplete any original ring material, unless active recycling re-uses and renews the rings. This implies a host of parent bodies among the rings, which serve both as sources and sinks for ring material. The present rings represent an active balance between production and destruction. Cassini discovered a number of small moons among the rings; together, these observations indicate the rings could be both young and old!

The dynamics of planetary rings has direct implications for proto-planetary disks around other stars. The process of planet formation is unlikely as smooth as we might have imagined. Proto-planets truncate the disk. Clumps and wakes may initiate planet formation and stochastic events reverse it.

Tuesday, 18 October 2005
3845 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM