Geological Chronicle
Located in the rugged southern highlands of the Moon, Buch spans 51.31 kilometers across and presents the softened outline of an old, worn crater. It lies to the northeast of the large crater Maurolycus, and the comparably sized crater Büsching is attached to its northeast rim.
The rim has been eroded by many lesser impacts so that the edge is rounded and worn down, forming only a low depression. Buch is slightly elongated in the northeastern direction, producing an egg-shaped depression. Within the crater, the floor is relatively flat and featureless, with no central peak at the midpoint and only a tiny crater near the northern inner wall.
Satellite crater Buch B is unusual in possessing both a dark halo of material around its rim and dark rays. Early speculation considered the feature volcanic in nature, but subsequent work showed it to be an ordinary impact crater formed over a pocket of darker material. Buch B dates to the Copernican period and contains meteoritic iron-rich impact melt.
The formation is named after German geologist Christian Leopold von Buch. German astronomer J. H. von Mädler incorporated its name into lunar nomenclature during the nineteenth century, and the designation was formally adopted by the International Astronomical Union in 1935.