C. Mayer (Moon)

Named after Christian Mayer - German astronomer, mathematician, physicist (1719-1783).

Also to the south, but only a third as distant, is the smaller crater Sheepshanks. C. Mayer is a young formation, with a sharp-edged and well-defined outer rim. The rim is not quite circular, and appears somewhat polygonal-shaped with outward bulges along the edge, most notably to the west. (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.