This is one of the youngest known craters on the Moon: it was violently excavated from the lunar surface on April 14, 1970! No one saw it hit, but we know it happened then because we
were the ones who made it: it was formed when the upper-stage Saturn V booster from Apollo 13 slammed into the Moon!
This Lunar Reconnaissance Orbiter image has lots of hints to tell us this is where the booster hit: for one, the bright rays extending from the crater - made as dust plumes from the impact settled - indicate how young the hole is; they fade with time. The size of the crater (about 30 meters across) is what's expected from such an event. And of course, the impact point was known.
I almost put this in the Top 14 list, but the LRO shot of the boulder that rolled into the crater tickled me more. Get the hi-res version here.Image credit: NASA/GSFC/Arizona State University