Cassegrain (Moon)

Named after Laurent Cassegrain - French astronomer, doctor (1629-1693).

Cassegrain is a lunar impact crater on the far side , beyond the southeastern limb. It lies to the southeast of the larger crater Lebedev, and to the northeast of the comparably-sized Priestley. The interior of this crater has a dark-hued floor, a feature it has in common with other craters to the west and northwest that form part of the Mare Australe. The floor is level and mostly featureless, except for some deposits in the northwest corner. (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.