St. John (Moon)

Named after Charles Edward John - American solar physicist, astronomer (1857-1935).

St. John is an eroded lunar impact crater. This crater is situated to the northeast of the huge walled plain Mendeleev, and southwest of the crater Kohlschütter. To the east is the small crater Mills. (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.