What is "kopff"

Kopff is a lunar crater that lies along the eastern edge of the inner Mare Orientale impact basin, on the western limb of the Moon. In this position the crater is seen from on edge from the Earth, and its visibility is affected by libration. This situation makes it difficult to discern much detail about the crater unless it is viewed from orbit.

At one time this crater was considered to have formed due to volcanic activity, in contrast to most lunar craters which are considered to have been created through impacts. However it is more likely that the crater was formed by an impact against a surface that was still partly molten. This has left the crater with a sharp-edged, circular rim and a flat, dark-hued interior floor. Indeed, the albedo of the interior floor matches that of the lunar mare to the west. The southeast part of the floor is fractured with a series of narrow rilles. The floor along the northwest and northeast edges is more rugged, and these sections have escaped the lava that covered the remainder of the floor.