Mark Showalter: Unraveling the Mysteries of Planetary Rings

Planetary astronomer Mark Showalter of the SETI Institute's Carl Sagan Center for the Study of Life in the Universe is one of our planet's foremost experts on the rings surrounding Saturn and other planets. He shares the latest findings revealed at the annual meeting of the American Astronomical Society's Division of Planetary Sciences, with special focus on Uranus and Jupiter. Emily Lakdawalla catches up with the speediest spacecraft, while Bruce Betts and Mat Kaplan announce a new space trivia contest and the beginning of Planetary Radio's fifth anniversary contest.