Ptolemaeus (Moon)

Named after Ptolemy, Claudius Ptolemaeus - Greek astronomer, mathematician, geographer (c. 87-150).

Ptolemaeus Crater is a crater on Mars found in the Phaethontis quadrangle at 46.21° south latitude and 157.6° west longitude. The Soviet probe Mars 3 is thought to have successfully landed in Ptolemaeus Crater in 1971, but contact was lost seconds after landing. Mantle material that is believed to have fallen from the sky is visible in the crater. (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.