Hippalus

A crater on the eastern shore of Mare Humorum, notable for the system of concentric rilles (Rimae Hippalus) on its eastern rim.

Visual Description

Hippalus appeared as a prominent crater on the eastern edge of Mare Humorum, with its western wall partially breached by mare lava. The most distinctive feature was the system of concentric rilles (Rimae Hippalus) visible on the mare surface to the east of the crater. These rilles curved in arcs concentric with Mare Humorum, likely formed by subsidence of the mare floor. The combination of the crater and associated rille system made this an excellent telescopic target.

Notable Features

• Crater on Mare Humorum shore
• Western wall breached by lava
• Rimae Hippalus rille system to east
• Concentric rilles parallel to mare edge
• Excellent example of mare tectonics

Notes

• Named after ancient Greek navigator Hippalus
• Rille system is prominent feature
• Best observed 10-12 days after new moon
• Coordinates: 24.8°S, 30.2°W
• Requires good seeing for rille details