Ptolemaeus

The northernmost crater in the famous Ptolemaeus-Alphonsus-Arzachel chain in the lunar highlands.

Visual Description

Ptolemaeus appeared as a very large, ancient crater with low walls and a flat, featureless floor. The crater was the largest in the prominent north-south chain with Alphonsus and Arzachel. The floor appeared smooth and relatively dark, showing signs of partial lava flooding. The crater’s great size and subdued features indicated its ancient age.

Notable Features

• Very large diameter
• Flat, smooth floor (partially flooded)
• Low, worn walls
• Part of Ptolemaeus-Alphonsus-Arzachel chain
• Ancient, degraded structure

Notes

• Named after Greco-Roman astronomer Claudius Ptolemy
• Best observed 8-10 days after new moon
• One of the largest craters in the central highlands
• Coordinates: 9.2°S, 1.8°W
• Forms famous chain with Alphonsus and Arzachel