Balmer (Moon)

Named after Johann Jakob Balmer - Swiss mathematician, physician (1825-1898).

Balmer is the lava-flooded remains of a lunar crater. Only the heavily worn southern and eastern sections of the crater still survive; the remainder being overlaid by a lava flow that joins to the nearby mare. Balmer lies to the east-southeast of the crater Vendelinus. (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.