Gemma Frisius (Moon)

Named after Jemma, Reinier Frisius - Dutch doctor (1508-1555).

Gemma Frisius is a lunar crater that is located in the rugged southern highlands. It lies to the north of the walled plain Maurolycus, and southeast of the smaller crater Poisson. The crater Goodacre is attached to the northeast rim. The outer wall of this crater has been heavily damaged by impacts, particularly along the north and west sides. (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.