Dr. Michael Brown of Caltech shares the inside story of how he discovered "other Pluto's" out there beyond Neptune, including Eris, which is now known to be about the same size as Pluto. He named that new world for the goddess of discord, because, as he describes with his characteristic humor, its discovery resulted in a private and public controversy that led to a redefinition of what a planet is. Recorded January 19, 2011.