Clausius is a lunar crater that is located in the southwest part , in the small lunar mare designated Lacus Excellentiae. The rim is low and sharp, with a slightly oval shape that is longer in the north-south direction. The interior floor has been flooded by basaltic lava, and appears level and featureless with a darker surface that matches the mare surface that surrounds the crater exterior. (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.
