Dreyer (Moon)

Named after Johann Ludwig Emil Dreyer - Danish astronomer (1852-1926).

Dreyer is the remnant of a lunar crater on the far side. It is located along the eastern edge of the Mare Marginis, about midway. The rim of this crater is heavily worn, with multiple impacts overlaying the edge and a small gap at the south end. The satellite crater Dreyer C lies across the northeastern rim, while Dreyer K intrudes into the southeastern side. (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.