Calippus (Moon)

Named after Calippus of Cyzicus - Greek astronomer (c. 370 B.C.).

Calippus is a small lunar crater on the eastern edge of the rugged Montes Caucasus mountain range in the northern part. It lies to the southwest of the crater remnant Alexander, to the northwest of the Mare Serenitatis. The outer rim has an irregular appearance, with outward bulges to the northeast and particularly to the west where there is an interior shelf of slumped material. The exterior has a slight rampart that is surrounded by the rugged terrain of the mountain range. (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.