Geological Chronicle
Oppenheimer is a large lunar impact crater measuring 201.16 kilometers in diameter on the far side of the Moon. Situated along the western outer rampart of the immense walled plain named Apollo, the formation dates to the Nectarian period of the lunar geologic timescale. Its outer rim is very nearly circular, broken in several locations by small craters, the most prominent of which is Oppenheimer H lying against the inner wall and rim.
The inner wall is unusually narrow along the western rim, but widens considerably across the eastern half near where the crater approaches the Apollo basin. The interior floor is relatively level, particularly near the center, and displays several patches of lower albedo near the western rim, including one that contains the flooded crater Oppenheimer U.
Near the northern and southern inner walls, a system of linear rilles marks the surface, while the far eastern half of the crater is crossed by a north–south ray system. Before the International Astronomical Union formally adopted the name in 1970 in honor of American physicist J. Robert Oppenheimer, the crater was designated Crater 382.