Geological Chronicle
Hipparchus is an ancient lunar impact crater with a diameter of 143.95 kilometers, located southeast of Sinus Medii near the center of the visible Moon. Its western rim has been all but worn away from impact erosion, leaving only low hills and rises in the surface to outline the feature. The wall to the east is somewhat more intact, but it too is heavily worn. A pair of deep clefts lie in the western wall, paralleling a set of scars running through the south-central highlands. To the south is the prominent crater Albategnius, and to the southwest lies Ptolemaeus, a feature of comparable dimensions to Hipparchus.
The crater floor has been partially resurfaced by basaltic lava flow, although the southwest part of the floor is slightly raised and much more rugged than the remainder. A few small rises and the raised partial rim of a flooded crater are all that remain of a central massif. Along the northwest rim of Hipparchus, gaps form valleys that connect with the mare to the northwest, and a rille named Rima Réaumur runs from this site to the outer wall of Réaumur. Horrocks lies entirely within the northeast rim of the crater. Halley is attached to the south rim, and Hind lies to the southeast. To the north-northeast is the bowl-shaped Pickering, and the flooded Saunder is located off the northeast rim.
It was named after the Greek astronomer, geographer and mathematician Hipparchus. In October 1664, Robert Hooke used a 36-foot telescope to make a detailed drawing of the single crater Hipparchus and surrounding terrain, which he published as a plate in his Micrographia (1665). His drawing contained an abundance of detail, and can be considered the first high-definition illustration of an individual lunar feature. Hooke argued that its features were not fixed, but were a product of ongoing physical forces, suggesting two possible models to explain lunar crater formation: projectile bombardment from space and subterranean lunar vulcanism. In the original version of the 1954 Tintin book Explorers on the Moon, the crew lands on Hipparchus. High-resolution images of Hipparchus were obtained by Lunar Orbiter 5 in 1967.