Cassini 40.2°N, 4.6°E

Cassini is a very conspicuous crater, 56 km in diameter, lying at the southern end of the Alps. It is a prominent landmark in this area of the Moon. The outer crater wall appears rounded and smooth because of deposits of melted ejected material – as with Archimedes and Aristoteles.

On high-resolution images the ejecta, which lies in a ring around the outer crater rim, appears remarkably smooth and wavy. It gives that impression that the impact onto the lunar surface took place into semi-fluid material with a consistency like that of mud. Considered morphologically, the crater and its immediate surroundings resembles those craters on Mars that are classified as ‘rampart craters’. There, however, sub-surface ice plays a part, which is liquified by the impact and turns the soil surrounding the impact into a muddy consistency.

The floor of Cassini is slightly rounded and appears extremely smooth. A chain of hills stretches from the inner crater wall to the crater Cassini A (15 km). It is crossed by a narrow, valley-like structure. Cassini B (9 km) also lies inside the crater, and between them lie two mountain peaks. A craterlet of about 2 km in diameter lies directly on the northern crater wall.

Cassini M (8 km) lies immediately next to the outer rampart on the northwest. From there a valley-like trough runs more than 20 km northwards. An interrupted, very narrow, nameless rille lies between Cassini and the crater Calippus. Large telescopes using webcam techniques have revealed half-a-dozen additional crater pits on the floor of Cassini.