Named after Georg Joachim von Lauchen of Rhaetia Rhaeticus - Hungarian astronomer, mathematician (1514-1576).
Rhaeticus is a lunar crater that lies astride the equator , on the southeast edge of the Sinus Medii. To the north-northwest is the crater Triesnecker, and due south can be found the worn remnant of the walled plain Hipparchus. The crater was named for Georg Joachim von Lauchen, also known as Rheticus. The outer wall is heavily disintegrated, with rifts and notches in the northeast. (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.