Stefan (Moon)

Named after Josef Stefan - Austrian physicist (1835-1893).

Stefan is a lunar crater on the far side , just beyond the northwestern limb. Attached to the western rim is the slightly smaller crater Wegener, and close to the eastern rim is Rynin. As with many craters of this size , the outer rim has been worn by impact erosion and the edge and inner wall are generally pitted with small craterlets. The southern edge of the rim in particular has been damaged by impacts, and is overlain by the satellite crater Stefan L. This bowl-shaped crater lies at the center of a small ray system, which is indicative of a young impact. (wikipedia entry)

A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.