Geissler (Moon)

Named after Heinrich Geissler - German physicist (1814-1879).

Geissler is a small lunar impact crater that lies on the northern floor of the much larger walled plain Gilbert, near the eastern limb. Just to the northeast of this crater, attached to the outer rim of Gilbert, is the crater pair of Weierstrass and Van Vleck. The rim is nearly circular, with a slight outward bulge toward the northwest. The rim is sharp-edged and not notably worn. (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.