Maclear is a lava-flooded crater on the northwest part of the Mare Tranquillitatis, a lunar mare in the eastern half of the Moon. Its diameter is 20 km.[1] The crater is located to the southwest of the slightly larger Ross. To the southwest of Maclear is Sosigenes, while farther to the south-southeast is Arago.
With most of its interior submerged in deposits of basaltic lava, all that remains of this crater is a narrow rim projecting above the surrounding mare. The rim is not quite circular, having a flat outward bulge along the western side. But the rim is relatively uniform in width and is not significantly eroded.
The crater rim lies at the southern terminus of a rille belonging to a system that runs along the western edges of Mare Tranquillitatis. The rille system to the north of the crater is designated Rimae Maclear, while the rilles to the south-southwest are named Rimae Sosigenes. The Rimae Maclear stretches for about 100 kilometers, reaching Al-Bakri to the north along the edge of the mare.
Menzel, D. H.; Minnaert, M.; Levin, B.; Dollfus, A.; Bell, B. (1971). "Report on Lunar Nomenclature by the Working Group of Commission 17 of the IAU". Space Science Reviews. 12 (2): 136–186. Bibcode:1971SSRv...12..136M. doi:10.1007/BF00171763. S2CID122125855.