Polybius (Moon)

Named after Polybius - Greek historian (204(?)-122(?) B.C.).

Polybius is a lunar impact crater in the southeast part. It is located to the south-southeast of the larger crater Catharina, in the area framed by the Rupes Altai scarp. Some distance to the northeast is the Mare Nectaris, with the flooded craters Beaumont and Fracastorius. The crater rim appears slightly distended in the northeast, and has a cut through the northern wall. (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.