Giordano Bruno (crater)
Giordano Bruno is a small crater on the moon, whose eponym is the Italian philosopher Giordano Bruno. It has a prominent ray system. Were it not for the fact that it was possibly formed less than 1000 years ago, it would just be an obscure crater.
Shortly after sunset on June 18, 1178, five monks from Canterbury reported seeing what they described as two horns of light on the shaded part of the moon. Modern theories predict that there would be a plume of molten matter rising up from the surface of the moon, which is consistent with the monks' description. In addition, the location they recorded fits in well with Bruno's location. Additional evidence of Bruno's youth is its spectacular ray system: because micrometeorites constantly rain down, they kick up enough dust to quickly (in geological terms) erode a ray system. So there is probably enough circumstantial evidence to hold that Giordano Bruno was formed during human history.
However, the question of Bruno's age is not that simple. The impact creating the 22km wide crater would have kicked up enough debris to make a meteor storm on Earth with roughly 50,000 meteors per hour, for up to a week. There is no way the entire population of the planet could possibly have missed the greatest fireworks show in history! This is such a major objection that few astronomers still believe Bruno formed then.
All this raises the question of what did the monks see? An alternative theory holds that the monks just happened to be in the right place at the right time to see an exploding meteor coming at them and aligned with the Moon. Only a small area in Britain would have the perfect geometry to make it look like it was on the Moon.
