NASA - A Meteoroid Hits the Moon: "June 13, 2006: There's a new crater on the Moon. It's about 14 meters wide, 3 meters deep and precisely one month, eleven days old.
NASA astronomers watched it form: 'On May 2, 2006, a meteoroid hit the Moon's Sea of Clouds (Mare Nubium) with 17 billion joules of kinetic energy—that's about the same as 4 tons of TNT,' says Bill Cooke, the head of NASA's Meteoroid Environment Office in Huntsville, AL. 'The impact created a bright fireball which we video-recorded using a 10-inch telescope.'
Lunar impacts have been seen before--'stuff hits the Moon all the time,' notes Cooke--but this is the best-ever recording of an explosion in progress: