On June 30, 1908, an asteroid caused a massive air blast that flattened thousands of square miles in Siberia. To mark the 110 year anniversary of the largest impact-related event in modern history, we brought in asteroid experts to discuss the threats asteroids pose and how we are protecting ourselves from the danger they may cause. The discussion will be moderated by the Applied Physics Laboratory's Cheryl Reed, who works on the asteroid deflection demonstration mission.

Speakers include:

•Museum geologist Jim Zimbelman on the importance of impacts throughout the solar system

•NASA astronaut Tom Jones on the asteroid hazard from a scientist-astronaut's perspective

•NASA scientists Lindley Johnson and Kelly Fast on NASA's planetary defense activities

This program is in recognition of Asteroid Day, a UN-sanctioned global awareness campaign.