Discover how astronomers determined the unexpected brightening of an asteroid named Scheila was likely the result of an impact with a much smaller asteroid. This video from NASA looks at how the Swift satellite and the Hubble Space Telescope helped astronomers investigate what they thought was an unusual comet but was actually the aftermath of a collision between asteroids. Astronomers ruled out the possibility of a comet, using data about the shape, evolution, and content of the dust plumes to help them reconstruct what happened.