Geological Chronicle
Pytheas is a small lunar impact crater located in the southern part of Mare Imbrium, to the south of the crater Lambert. Spanning 18.81 kilometers in diameter, the crater was named after ancient Greek navigator and geographer Pytheas of Massalia.
The crater has a sharply defined rim, a hummocky outer rampart, and an irregular interior produced by slumping or fallback. Spectral analysis in the infrared has identified pure crystalline plagioclase on its central peak.
Pytheas possesses a small ray system extending roughly 50 kilometers in radius, surrounded by lunar mare dusted with ray material from Copernicus to the south. A small crater lies along its northern outer rampart, and a similar crater sits about 20 kilometers to the west.