Seeliger is a small lunar impact crater that lies near the southeastern edge of Sinus Medii. To the southeast is a rille named the Rima Réaumur, following a line to the northwest. In the north is the 110-km-long Rima Oppolzer, which divides the mare where Seeliger is situated from the remainder of the Sinus Medii. (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.
