Stearns is a lunar impact crater on the far side. Unlike many lunar craters, this is a fresh and well-defined impact feature with little appearance of erosion. The rim edge is sharp and roughly circular, with some unevenness. The inner walls are simple slopes down to piles of talus along the base. (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.