Geological Chronicle
Thebit is a lunar impact crater on the southeast shore of Mare Nubium, spanning 54.64 kilometers in diameter. Crater Arzachel lies to the north-northwest, Purbach lies to the south-southwest, and the flooded remnants of Thebit P lie to the southwest. Assigned to the Upper (Late) Imbrian period, Thebit has a circular rim with a double-notch in the southwest wall, a terrace, a hilly outer rampart, and a rough floor with no central peak.
The crater is relatively simple to identify by an arrangement of subsequent impacts along its perimeter. The prominent bowl-shaped crater Thebit A lies across the west-northwestern rim, and the west-northwestern rim of Thebit A is overlain in turn by the smaller Thebit L. Due west of Thebit is Rupes Recta, a 110-kilometer-long ridge that rises to 240 meters.
Thebit lies on the eastern rim of a much older 220-kilometer crater informally known as Ancient Thebit. Its eroded rim persists to the northwest and southwest, and Rupes Recta, Birt, and Rima Birt all lie within Ancient Thebit. The name is a Latinization of 9th-century Iraqi astronomer and mathematician Thābit ibn Qurra.