Named after Edward Arthur Milne - British mathematician, astrophysicist (1896-1950).
Milne lies to the northeast of the Mare Australe, and southeast of Lacus Solitudinis. The southern portion of the wall has been obliterated by impacts, and this area is now overlain by the craters Milne M and Milne N. Milne N has a ray system and is mapped as part of the Copernican System. Although the interior floor is flat, it has been marred by many impacts in the surface. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.