NASA tracks more than 10,000 Near Earth Objects (NEOs) in space. Millions of years ago, one of these NEOs hit Earth, wiping out the dinosaurs. No person has every been killed by one in recorded human history. Using Purdue University’s Impact Earth and data from NASA, we calculated the destruction different size asteroids would cause if they hit land. Produced by Kevin Reilly. Animations by Rob Ludacer. Special thanks to Julia Calderone.