Dr. Mark Showalter

December 22, 2006

"Rings of Uranus: Dynamics, Properties and Shepherding Moons"

HST–GO–10102.03

This project consists of two observing programs running on the Hubble Space Telescope, focusing on the ring systems of Uranus and Neptune. Uranus has a set of narrow rings and a family of 13 nearby moons. Our Uranus observations in August 2003 discovered the two smallest of these moons, currently designated S/2003 U 1 and S/2003 U 2. Both bodies are only a few miles across, perhaps the size of San Francisco. It is a testament to the remarkable capabilities of the Hubble telescope that we are able to see bodies from Earth that were too small to be detected by Voyager's cameras during the 1986 flyby. Our work on Neptune's ring system is just beginning but our first observations clearly show its mysterious arcs, incomplete rings that have held together for at least 20 years now.