It's been said that our universe is a cosmic shooting gallery. Gravity is moving everything around and things are bound to collide. Astronomers are attempting to understand how these collisions occur in the dark recesses of space. Learn about collisional families, which are clusters of comets and asteroids; planetary collisions; mass extinction impacts involving asteroids and comets; stars collisions; and galaxy cluster collisions. Cutting-edge computer graphics are used to bring this series down to earth as the heavens yield their greatest secrets.