Geological Chronicle
Situated near the northwest limb of the Moon, Babbage is an ancient and eroded lunar formation attached to the southeastern rim of the prominent crater Pythagoras. Rather than an ordinary single impact crater, it is described as having formed by fusion of two large rings. The crater remnant named South intrudes into the southeastern floor of Babbage.
Subsequent impacts eroded and modified the outer rim until all that remains is a ring of rounded hills. Patrick Moore noted that the wall of Babbage is so broken and discontinuous that it is often difficult to recognize. The most notable modification is the satellite crater Babbage D, which overlays the southwestern rim with a broken, disorganized northeast rim that forms a bay on the perimeter. Oenopides is another worn formation attached to the southwest edge of this protuberance.
Inside Babbage, the outer rampart of Pythagoras lies across the floor, forming a region of rough terrain in the northwest part of the interior. The rest of the crater floor is relatively flat, marked by many tiny craterlets. The interior's most notable feature is the satellite crater Babbage A in the southeast part of the interior; it has not been significantly worn and appears much younger than the remainder of the formation, accompanied just to the west by the smaller, bowl-shaped Babbage C.