Named after Walther Hermann Nernst - German physical chemist; Nobel laureate (1864-1941).
Nernst is a lunar impact crater that lies on the far side , just beyond the northwestern limb. It lies across the northern part of the larger walled plain Lorentz, and intrudes slightly into the northwestern rim of the crater Röntgen. The rim is well-defined, although several smaller impacts lies across the edge. The satellite crater Nernst T has broken through the western rim edge. (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.