117: Guardians of (a very small part of) the galaxy with Dr. Fast

Dr. Kelly Fast tells us about the Planetary Defense Coordination Office, which finds asteroids before they find us. She talks about a recent exercise involving the tiny asteroid 2012 TC4, where asteroid hunters across the world coordinated to observe this object on a recent fly-by. We also talk about 'Oumuamua, the first interstellar asteroid ever discovered.