Calippus is a small lunar crater that is located on the eastern edge of the rugged Montes Caucasus mountain range in the northern part of the Moon. It lies to the southwest of the Alexander crater remnant, to the northwest of the Mare Serenitatis.
The outer rim of Calippus has an irregular appearance, with outward bulges to the northeast and particularly to the west where there is an interior shelf of slumped material. The exterior has a slight rampart that is surrounded by the rugged terrain of the mountain range. Within the sharp-sided interior walls is a rough and irregular interior floor.
To the southeast of this crater, on the edge of the Mare Serenitatis, is an arcing rille designated Rima Callipus. This cleft follows a path to the northeast for a length of about 40 kilometers.
By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Calippus crater.
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