Isidorus is a lunar crater that is located to the north of the Mare Nectaris, on the eastern half 's near side. It forms a pair with the slightly larger Capella, which is attached to the east-northeastern rim. To the west-southwest across the lunar mare are Mädler and the prominent Theophilus. The rim is circular and somewhat eroded, with several tiny craterlets lying across the northern rim. (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.
