Necho (crater)

Necho (crater) is a prominent lunar impact crater located on the Moon's far side, beyond the visible limb from Earth. It is situated to the east of the immense Mare Orientale impact basin and lies within the rugged southern highlands. The crater is notable for its sharp, well-defined rim, terraced inner walls, and a complex central peak structure, making it a significant feature for geological study.

Description

Necho is a relatively young crater, classified as a complex crater due to its size and internal structure. Its rim is approximately circular with a sharp, scalloped edge that shows little sign of significant erosion from subsequent impacts. The inner walls display prominent terracing, formed by the collapse of the crater's initial transient cavity, which slopes down to a relatively flat floor. At the center of the floor rises a prominent, mountainous central peak complex, typical of larger impact craters, which is composed of material uplifted from great depths during the impact event. The crater's ejecta blanket extends outward in a radial pattern, overlaying the older, heavily cratered terrain of the Lunar highlands. Necho is located in a region southeast of the Dirichlet-Jackson Basin and northwest of the larger crater Minkowski, within the broader geological context of the South Pole–Aitken basin.

Origin of name

The crater is named for Necho II, a pharaoh of the Twenty-sixth Dynasty of Egypt who reigned in the late 7th century BCE. The name was officially adopted by the International Astronomical Union (IAU) in 1970, following their established convention of naming lunar craters after deceased scientists, explorers, and historical figures. The approval process for lunar nomenclature is managed by the IAU's Working Group for Planetary System Nomenclature (WGPSN). Necho II is historically noted for his ambitious projects, including attempts to construct a canal linking the Nile to the Red Sea and for sponsoring a famed Phoenician expedition that may have circumnavigated Africa, as recorded by the ancient Greek historian Herodotus.

Satellite craters

By convention, smaller craters associated with Necho are identified on lunar maps by placing a letter on the side of the crater's midpoint that is closest to Necho. These satellite craters provide additional context for understanding the impact history of the region. * Necho C: A small, bowl-shaped crater attached to the northeastern outer rim of Necho. Its formation post-dates Necho, as its ejecta partially covers the larger crater's rim. * Necho F: Located to the southwest of the main crater, this is a distinct, somewhat eroded impact feature situated on Necho's extended ejecta blanket. * Necho T: A small, sharp-rimmed crater to the northwest, which serves as a useful marker for stratigraphic studies comparing the ages of nearby features. The presence of these satellite craters, along with others like Necho X and Necho Z, helps planetary geologists establish a relative chronology of impact events in this sector of the lunar far side.

Related features

Necho is situated within a complex geological region influenced by several major basins. It lies to the east of the multi-ringed Mare Orientale, one of the youngest large impact basins on the Moon, whose formation likely affected the local tectonics. To the south and west, the terrain is part of the enormous and ancient South Pole–Aitken basin, the largest known impact crater in the Solar System. Other notable craters in the broader vicinity include Minkowski to the southeast, Fizeau to the north, and Lagrange farther to the southwest. Studies of Necho and its neighbors contribute to understanding the stratigraphy and bombardment history of the lunar far side, with data gathered from missions like Lunar Orbiter, Apollo, and more recently, Lunar Reconnaissance Orbiter.

Category:Impact craters on the Moon Category:Far side of the Moon