Arnold (Moon)

Named after Christoph Arnold - German astronomer (1650-1695).

Arnold is a lunar crater that is located in the north-northeastern part of the visible Moon, near the lunar limb. This location gives the crater a notably oval appearance due to foreshortening, although the formation is actually round. It lies to the northeast of the Mare Frigoris, to the north of the crater Democritus. West is the smaller crater Moigno. (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.