The Moon is a long, long way away from Earth.
That leaves a lot of empty space surrounding the Moon, where anything could get to it from all angles.
PIA00559: The Earth and Moon As Seen by 2001 Mars Odyssey's Thermal Emission Imaging System
Image Source: https://photojournal.jpl.nasa.gov/catalog/PIA00559
RE: Whats The Deal With The Moon's Craters