Petermann is a lunar crater that is located near the northern limb , on the eastern hemisphere. It is located about 10 kilometres to the north of the crater Cusanus. Due to its location, this crater appears significantly foreshortened when viewed from the Earth, and its visibility can be affected by libration. Attached to the western rim of this crater is the large, heavily eroded crater Petermann R, which is much larger than Petermann although less prominent in appearance. (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.