Planetary smash-up: A high-speed collision in space
Another favorite from Hollywood’s file of doomsday scenarios: Could a planetary collision spell the end of Earth? NASA’s Spitzer Space Telescope has found evidence that this has happened in our galaxy. The young star HD 172555, just 100 light-years from Earth, may have been the center of a smash-up because NASA has found rubble, as well as signatures of vaporized and melted rock, around the star.
Has such a smash-up every happened in our solar system? Some experts believe that it has. In fact, our moon is thought to have formed when a fast-moving object slammed into the Earth some 30 million to 100 million years after the now 4.5 billion year old sun formed. The molten rock, vapor and debris that were flung off the Earth eventually coalesced into what is now our natural satellite.