William Hartmann on 100th Anniversary of Tunguska's Big Bang

Early on the morning of June 30, 1908, a peaceful Siberian forest was suddenly leveled by the explosion of a meteor. Scientist, author and artist Bill Hartmann returns to Planetary Radio to talk about this event. Emily Lakdawalla provides another Phoenix Mars mission update. Bill Nye reports on his visit to Congress. Catch the winner of the Random Space Fact recording contest on this week's What's Up with Bruce Betts and Mat Kaplan, which includes a chance to win an Explorer's Guide to Mars poster.