Rydberg (Moon)

Named after Johannes Robert Rydberg - Swedish physicist (1854-1919).

Rydberg is a lunar impact crater on the far side , just past the southwest limb. It lies due south of the Mare Orientale, in the outer skirt of ejecta that surrounds the Orientale impact feature. Just to the southeast is the crater Guthnick. This is a little-eroded crater formation with a sharp 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.