Galen (crater)

Galen is a lunar impact crater that lies on the western edge of Mare Tranquillitatis. It is located to the east of the prominent crater Theon Senior, and is somewhat isolated from other named features.

Galen is a relatively small, bowl-shaped crater with a sharp, well-defined rim. Its interior is somewhat rough, with a higher albedo than the surrounding mare. There is no central peak. Due to its relative isolation and lack of significant features, Galen is often used as a landmark for lunar observers.

The crater is named after Claudius Galenus, a prominent Greek physician, surgeon and philosopher in the Roman Empire.