Happy Asteroid Day!

Asteroid Day, June 30th, marks the anniversary of the great Tunguska impact that leveled a Siberian forest. It reminds us that a Near Earth Object can destroy a city or even a civilization. Former Minor Planet Center Director Tim Spahr reviews our efforts to find and understand these bodies. Related links and the weekly space trivia contest are here: http://www.planetary.org/multimedia/planetary-radio/show/2017/0628-tim-spahr-asteroid-day.html