Geological Chronicle
Situated in the northeastern quadrant of the Moon, Cepheus spans 39.43 kilometers in diameter and lies within one crater diameter northwest of the larger crater Franklin. Because of its location near the lunar limb, foreshortening gives the formation an oblong profile when viewed through Earth-based telescopes.
The crater formed during the Eratosthenian period, leaving behind a sharp, well-defined rim. Its outline remains nearly circular, modified by outward bulges to the north and south and interrupted on the northeast crest by Cepheus A, an even younger bowl-shaped satellite crater.
Terracing lines parts of the inner wall, most clearly along the northwest slope, while an elongated central peak rises across the middle of the floor. Surrounding the rim, the lunar regolith forms a radar-dark halo, indicating that deposited ejecta around the structure contains few meter-sized rock blocks.
Italian selenographer Giovanni B. Riccioli introduced the name in 1651, initially assigning it to the feature now known as Franklin. The International Astronomical Union officially adopted the designation in 1935, honoring the mythological king of Aethiopia and father of Andromeda.