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Pre-Nectarian
The pre-Nectarian period of the lunar geologic timescale runs from 4.533 billion years ago (the time of the initial formation of the Moon) to 3.920 billion years ago, when the Nectaris Basin was formed by a large impact. It is followed by the Nectarian period. Description Pre-Nectarian rocks are rare in the lunar sample suite; they are mostly composed of lunar highlands material which have been heavily churned, brecciated, and thermally affected by subsequent impacts, particularly during the Heavy Bombardment Eon (HBE; a period of 0.6-1 Gy from the formation of the Moon until at least the formation of the Imbrium Basin ~3.9 Ga, or even later with the formation of Orientalis Basin) that marks the approximate beginning of the Nectarian period. The primary pre-Nectarian lunar highland material is dominated by the rock type anorthosite, which suggests that the early stage of lunar crustal formation occurred via mineral crystallization of a global magma ocean. This geologic period has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Geologic Timescale
The lunar geological timescale (or selenological timescale) divides the history of Earth's Moon into five generally recognized periods: the Copernican period, Copernican, Eratosthenian, Imbrian (Late Imbrian, Late and Early Imbrian, Early epochs), Nectarian, and Pre-Nectarian. The boundaries of this time scale are related to large impact events that have modified the lunar surface, changes in impact crater, crater formation through time, and the size-frequency distribution of craters superposed on geological units. The absolute ages for these periods have been constrained by radiometric dating of samples obtained from the lunar surface. However, there is still much debate concerning the ages of certain key events, because correlating lunar regolith samples with geological units on the Moon is difficult, and most lunar radiometric ages have been highly affected by an intense history of bombardment. Lunar stratigraphy The primary geological processes that have modified the lunar sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basin Groups
Basin Groups refers to 9 subdivisions of the lunar Pre-Nectarian lunar geologic timescale, geologic period. It is the second era of the Hadean. Definition The motivation for creating the Basin Groups subdivisions was to place 30 pre-Nectarian impact basins into 9 relative age groups. The relative age of the first basin in each group is based on crater densities and superposition relationships, whereas the other basins are included based on weaker grounds. Basin Group 1 has no official age for its base, and the boundary between Basin Group 9 and the Nectarian period is defined by the formation of the Nectaris impact basin. The age of the Nectaris basin is somewhat contentious, with the most frequently cited numbers placing it at 3.92 Ga, or more infrequently at 3.85 Ga. Recently, however, it has been suggested that the Nectaris basin could be, in fact, much older and might have formed at ~4.1 Ga. Basin Groups are not used as a geologic period on any of the United States Geological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mare Nubium
Mare Nubium (Latin ''nūbium'', the "sea of clouds") is a lunar mare in the Nubium basin on the Moon's near side. The mare is located just to the southeast of Oceanus Procellarum. Formation The basin containing Mare Nubium is believed to have been part of the Pre-Nectarian system. The mare material is of the Imbrian and Eratosthenian age. Bullialdus crater, a prominent feature on the west side of the mare, is of Eratosthenian age. Other features within the mare include Pitatus on the southern margin and Guericke bounding the mare to the north. Opelt, Gould, Kies, Nicollet, Wolf, Birt, and Rupes Recta (the Straight Wall) lie within the mare. Names Like most of the other maria on the Moon, Mare Nubium was named by Giovanni Riccioli, whose 1651 nomenclature system has become standardized. Previously, William Gilbert had included it among the Continens Meridionalis ("Southern Continent") in his map of ''c''.1600, and Michael Van Langren had labelled it the Mare Borbon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mare Smythii
Mare Smythii (Latin for "Smyth's Sea") is a lunar mare located along the equator on the easternmost edge of the Moon's near side. It is named for the 19th-century British astronomer William Henry Smyth. The Smythii basin where the mare is located is of the Pre-Nectarian epoch, while the surrounding features are of the Nectarian system. It is contained within a minimal diameter of , and has been excavated to a depth of . The mare material, which makes up the floor of the mare, is a low alumina basalt, and consists of Upper Imbrian basalt covered by Eratosthenian basalt. Features observed within the basin include wrinkle ridges, submerged "ghost" craters, domes, crater chains, and rilles. The overall shape of the mare is circular, likely the result of a large impact. Further bombardment followed, creating the irregular shape. Subsequent volcanism laid down the mare material. As a result of this sequence, only the northeastern portion and a smaller area in the western central cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coulomb-Sarton Basin
The Coulomb-Sarton Basin is a Pre-Nectarian impact basin on the far side of the moon. It is named after the crater Coulomb northeast of the center of the basin and the smaller crater Sarton just south of the center. The basin is not obvious on the lunar surface. There are only small fragments of inner rings and a rim, and the most indicative topographic feature is a smooth, low plain at the center. At the center is a mass concentration (mascon), or gravitational high. The mascon was first identified by Doppler tracking of the Lunar Prospector spacecraft. The existence of the basin was confirmed by the GRAIL spacecraft. Other craters within the basin include Weber and Kramers. At the approximate margin of the basin are Dyson, Ellison, Stefan, Wegener, Wood, Landau, and Gullstrand. The large crater Birkhoff is to the northwest. File:Coulomb-Sarton basin topo.jpg, Topographic map File:Coulomb-Sarton basin GRAIL gravity.jpg, Gravity map based on GRAIL The Gravity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freundlich-Sharonov Basin
The Freundlich-Sharonov Basin is a Pre-Nectarian impact basin on the far side of the moon. It is named after the younger craters Freundlich near the northwest margin and Sharonov near the southwest margin. It lies east of Mare Moscoviense basin and northwest of Korolev basin. The basin is not obvious on lunar photographs, although it was discovered from analysis of Lunar Orbiter photographs. At the center is the small mare Lacus Luxuriae, just south of the oblique crater Buys-Ballot. Also at the center is a mass concentration (mascon), or gravitational high. The mascon was first identified by Doppler tracking of the Lunar Prospector spacecraft. Other craters within the basin include Anderson, Virtanen, Zernike, Dante, and the smaller Šafařík. Morse and Spencer Jones are at the margins. Views File:Freundlich-Sharonov basin topo.jpg, Topographic map File:Freundlich-Sharonov basin GRAIL gravity.jpg, Gravity map based on GRAIL File:Freundlich-Sharonov Basin AS16-M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Pole–Aitken Basin
The South Pole–Aitken basin (SPA Basin, ) is an immense impact crater on the far side of the Moon. At roughly in diameter and between deep, it is one of the largest known impact craters in the Solar System. It is the largest, oldest, and deepest basin recognized on the Moon. It is estimated that it was formed 4.2 to 4.3 billion years ago, during the Pre-Nectarian epoch. It was named for two features on opposite sides of the basin: the lunar South Pole at one end and the crater Aitken on the northern end. The outer rim of this basin can be seen from Earth as a huge mountain chain located on the Moon's southern limb, sometimes informally called "Leibnitz mountains". On 3 January 2019, the Chang'e 4, a Chinese spacecraft, landed in the basin, specifically within a crater called Von Kármán. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mare Ingenii
Mare Ingenii (Latin ''ingeniī'', the "Sea of Cleverness") is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin, which is of the Pre-Nectarian epoch, which lies in turn in the outer part of the older and much larger South Pole–Aitken basin. The mare material located in Ingenii and the surrounding craters is of the Upper Imbrian epoch. The dark circular feature which dominates this mare is the crater Thomson (112 km diameter), with the overflow from Ingenii/Thomson directly to the east. Mare Ingenii is incompletely and thinly covered over much of its expanse with mare lava sheets. The light grey crater to the south of Mare Ingenii is Obruchev. The mare has swirling patterns of bright material, similar to Reiner Gamma and to patterns within Mare Marginis, which are not associated with topographic or volcanic features. The lunar swirls are believed to be associated with magnetic fields. Prior to formal naming in 1961 by the IA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schiller-Zucchius Basin
The Schiller-Zucchius Basin is a Pre-Nectarian impact basin on the near side of the moon. It is named after the elongated crater Schiller at the northeast margin and fresh crater Zucchius near the southwest margin. This basin has received the unofficial designation 'Schiller Annular Plain' among lunar observers. The basin has a clear but eroded outer rim and a partial inner ring. It is thus an example of a peak ring basin. Also at the center is a mass concentration (mascon), or gravitational high. The mascon was first identified by Doppler tracking of the Lunar Prospector spacecraft. The existence of the basin was confirmed by the GRAIL spacecraft. Other craters within the basin include Segner and Weigel, as well as many satellite craters. Due south of the basin is Bettinus, to the northwest of the basin are Phocylides and Nasmyth, to the north is Nöggerath, and to the east is Rost. File:Schiller-Zucchius basin topo.jpg, Topographic map File:Schiller-Zucchius basi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mare Fecunditatis
Mare Fecunditatis (Latin ''fēcunditātis'', the "Sea of Fecundity" or "Sea of Fertility") is a lunar mare in the eastern half of the visible Moon. The mare has a maximum diameter of 840 km. __NOTOC__ Description The Fecunditatis basin formed in the Pre-Nectarian epoch, while the basin material surrounding the mare is of the subsequent Nectarian epoch. The mare material is of the Upper Imbrian epoch and is relatively thin compared to the neighboring Mare Crisium or Mare Tranquillitatis. This basin is overlapped with the Nectaris, Tranquillitatis, and Crisium basins. Fecunditatis basin meets Nectaris basin along Fecunditatis' western edge, with the area along this zone faulted by arcuated grabens. On the eastern edge of Fecunditatis is the crater Langrenus. Near the center lie the interesting craters Messier and Messier A. It was here that the first automated sample return took place via the Luna 16 probe, in September 1970. Sinus Successus lies along the eastern edge of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mare Australe
Mare Australe (Latin ''austrāle'' the "Southern Sea") is a lunar mare located in the southeastern hemisphere of the Moon. It is 997 kilometers in diameter, overlapping the near and far sides of the Moon. Smooth, dark volcanic basalt lines the bottom of the mare. The Australe basin was formed in the Pre-Nectarian epoch, while the mare material inside formed in the Upper Imbrian epoch. The basin was almost completely destroyed by impacts prior to the appearance of the mare. Unlike most of the lunar maria, Mare Australe has an uneven surface that is marked by a number of crater impacts. Examples of these include the craters Jenner and Lamb, which are flooded with basaltic lava much like many of the other crater features in this mare. The selenographic coordinates of this mare are 38.9° S, 93.0° E. The eastern half of the mare lies on the far side of the Moon, although it can be viewed in its entirety during periods of favorable libration. Gallery File:Mare Australe AS15-M-250 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mare Tranquillitatis
Mare Tranquillitatis (Latin ''tranquillitātis'', the Sea of Tranquillity or Sea of Tranquility; see spelling differences) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It is the first location on another world to be visited by humans. The mare material within the basin consists of basalt formed in the intermediate to young age group of the Upper Imbrian epoch. The surrounding mountains are thought to be of the Lower Imbrian epoch, but the actual basin is probably Pre-Nectarian. The basin has irregular margins and lacks a defined multiple-ringed structure. The irregular topography in and near this basin results from the intersection of the Tranquillitatis, Nectaris, Crisium, Fecunditatis, and Serenitatis basins with two throughgoing rings of the Procellarum basin. Palus Somni, on the northeastern rim of the mare, is filled with the basalt that spilled over from Tranquillitatis. This mare has a slight bluish tint relative to the rest of the Moon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
