There is more information available on this subject at Moon on the English Wikipedia.
Luna is Earth's moon. Like most bodies in the Solar System, Luna is littered with the debris of man's golden age. The surface of Luna appears to be shattered, with giant rifts in the ground and massive chunks tilted upward. One location on the moon is known as Hellmouth, a massive hole that goes deep into the moon's surface.[1] It is unknown what, if any, amount of combat takes place on Luna.