D'Arrest (Moon)

Named after Heinrich Louis D'Arrest - German astronomer (1822-1875).

D'Arrest is a lunar crater that is located in the lava-flooded region to the west of the Mare Tranquillitatis. It lies to the southeast of the crater Agrippa and northwest of Delambre. Just to the northeast are the small, bowl-shaped craters De Morgan and Cayley. The outer rim is broken in several places, with a gash at the south end and a wide gap to the northeast where only a low ridge remains in place of the original wall. (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.