Geological Chronicle
Positioned near the northwestern limb of the Moon, Pythagoras spans 144.55 kilometers in diameter and lies just northwest of the somewhat larger crater Babbage. Due to its oblique viewing angle from Earth, the crater presents an oval appearance, leaving only the western face of its interior visible while the opposite side remains permanently out of sight. Observer T. W. Webb described the formation as the deepest walled plain in this quadrant of the visible Moon.
On the lunar geologic timescale, Pythagoras is of Eratosthenian age, characterized by a well-preserved rim with a wide terrace system, a slight exterior rampart, and evidence of peripheral landslips. Although generally circular, the crater outline assumes a hexagonal form around a flattened floor with an irregular, hilly surface. In the center stands a sharp mountainous rise with a double peak ascending 1.5 kilometers above the crater floor, where surveys identified anorthosite with very low mafic abundance and the infrared spectrum of pure crystalline plagioclase.
Italian astronomer Giovanni Riccioli incorporated the name into lunar nomenclature in 1651 in honor of the Greek mathematician and philosopher Pythagoras of Samos. The International Astronomical Union formally adopted the designation in 1935.