How to Catch a Comet: Shoemaker-Levy 9 and the Rippled Rings of Jupiter

Dr. Showalter is a member of the Cassini Imaging Team and head of the PDS Rings node, which is housed at the SETI Institute. In this talk, Dr. Showalter will discuss the findings reported in his recent article in the journal Science.

Jupiter's ring shows vertical corrugations reminiscent of those recently detected in the rings of Saturn. The Galileo spacecraft imaged a pair of superimposed ripple patterns in 1996 and again in 2000. These patterns behave as two independent spirals, each winding up at a rate defined by Jupiter's gravity field. The dominant pattern originated between July and October 1994, when the entire ring was tilted by ~2 km.

Dr. Showalter will talk about how he and his colleagues found that the pattern is associated with the Shoemaker-Levy 9 impacts of July 1994. New Horizons images still show this pattern 13 years later and suggest that subsequent events may also have tilted the ring. Dr. Showalter will show that impacts by comets or their dust streams are regular occurrences in planetary rings, altering them in ways that remain detectable decades later.

Editor's Note:  The talk originally scheduled for this date, "Microbes and the four basic strategies for life on Earth: What we can learn from what we know (and how to look for what we don't know)" has been cancelled.