d'Alembert (Moon)

Named after Jean-Le-Rond d'Alembert - French mathematician, physicist (1717-1783).

D'Alembert is a large lunar impact crater located in the northern hemisphere on the far side , to the northeast of the somewhat smaller walled plain Campbell. Astride the southwest rim of D'Alembert is Slipher. To the north is the crater Yamamoto, and to the south-southwest lies Langevin. This walled plain has the same diameter as Clavius on the near side, making it one of the largest such formations. (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.