Sirsalis

Sirsalis is a lunar feature name that refers to both a crater and a nearby system of rilles on the Moon. The crater Sirsalis is an impact crater located on the Moon’s near side, in the western part of Oceanus Procellarum. It has a roughly circular rim and a relatively flat interior that has been partially flooded by basaltic lava. The rim shows moderate wear, indicating an appreciable age compared with some younger nearby features. The crater’s proximity to a major rille system gives it particular significance in selenography.

Rimae Sirsalis is a prominent network of sinuous lunar rilles that extends across the mare for a considerable distance. The rilles are believed to have formed as the Moon cooled and crust cracked, with later volcanic resurfacing filling parts of the channels. Together, the Sirsalis crater and the Rimae Sirsalis illustrate the interplay of tectonic and volcanic processes in the Moon’s history.

Observing notes suggest that Sirsalis can be observed with small to medium telescopes under favorable lighting, with better detail near the terminator when the shadows accentuate topography. The features are commonly used as reference points in lunar mapping and in discussions of mare volcanism and crustal deformation.