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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 Orientale 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 b ... [...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, Eratosthenian, Imbrian ( Late and 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 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 surface are impact cratering and volcanism, and by using ... [...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 approximately 4.2 to 4.3 billion years ago, during the Pre-Nectarian epoch (with radiometric dating of lunar zircons proposed to originate from the basin suggesting a precise age of 4.338 billion years). 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 Tranquillitatis
Mare Tranquillitatis (Latin for Sea of Tranquillity or Sea of Tranquility) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It contains Tranquility Base, the first location on another celestial body 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, Mare Nectaris, Nectaris, Mare Crisium, Crisium, Mare Fecunditatis, Fecunditatis, and Mare Serenitatis, Serenitatis basins with two throughgoing rings of the Oceanus Procellarum, Procellarum basin. Palus Somni, on the northeastern rim of the mare, is filled with the basalt that spilled over from Tranquillitatis. 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 ... [...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 t ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Geological Survey
The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The agency also makes maps of planets and moons, based on data from U.S. space probes. The sole scientific agency of the U.S. Department of the Interior, USGS is a fact-finding research organization with no regulatory responsibility. It is headquartered in Reston, Virginia, with major offices near Lakewood, Colorado; at the Denver Federal Center; and in NASA Research Park in California. In 2009, it employed about 8,670 people. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on its hundredth anniversary, was "Earth Science in the Public S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Werner (crater)
Werner is a prominent Lunar craters, lunar impact crater that lies in the rugged south-central highlands of the Moon. It was named after the 15th-century German mathematician and astronomer Johannes Werner. It is almost joined with the crater Aliacensis (crater), Aliacensis to the southeast, and the pair form a rugged valley in the intervening gap. Due west of Werner is the distorted Regiomontanus (crater), Regiomontanus, and to the north is the remains of Blanchinus (crater), Blanchinus. It is from the Eratosthenian period, which lasted from 3.2 to 1.1 billion years ago. The rim of Werner shows little appearance of wear, and is much younger and less eroded than the other large craters in the surroundings. The interior wall is wiktionary:terrace, terraced, and there is a noticeable rampart on the exterior. There are several low rises on the crater floor and a notable central peak. Its highly terraced walls attain peaks of almost 1,500 feet. The crater is 45 miles (70 kilometers) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vlacq (crater)
Vlacq is a prominent lunar impact crater that is located in the southeastern part of the Moon, and appears foreshortened when viewed from the Earth. This crater is adjacent to the northeastern rim of the larger Hommel, and to the northwest rim of Rosenberger. This crater has become eroded, but not to the degree of the larger neighboring craters. The satellite crater Vlacq G intrudes into the southern rim of Vlacq, and is overlaid in turn along the southwest rim by the sharp-rimmed Vlacq B. The satellite crater Vlacq C is attached to the northeastern exterior rim of Vlacq. The interior floor of Vlacq has been resurfaced by lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ..., leaving a nearly level base. The southwest half of the floor, however, is overlaid by ejecta from near ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nectaris Basin
Mare Nectaris (Latin ''nectaris'', the "Sea of Nectar") is a small lunar mare or sea (a volcanic lava plain noticeably darker than the rest of the Moon's surface) located south of Mare Tranquillitatis southwest of Mare Fecunditatis, on the near side of the Moon. Montes Pyrenaeus borders the mare to the east and Sinus Asperitatis fuses to its northwestern edge. It is 84,000 square kilometers in size. Several large craters are situated at the borders of Mare Nectaris. The biggest one is lava-filled Fracastorius (124 km), which fuses with the southern coast of the Sea. A prominent trio of 100-km craters Theophilus, Cyrillus and Catharina is located near northwestern coast. Other notable feature is a " ghost crater" Daguerre, almost entirely covered with lava, in the northern part of Mare Nectaris. Mare Nectaris is located in the central part of 860-km-diameter impact basin, which was formed 3.8–3.9 billion years ago. This event marks the beginning of Nectarian period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nectarian
The Nectarian Period of the lunar geologic timescale was from 3.920 billion years ago to 3.850 billion years ago. It is the period during which the Nectaris Basin and other major basins were formed by large impact events. Ejecta from Nectaris form the upper part of the densely cratered terrain found in lunar highlands. The period ended with the formation of the Imbrium basin, which initiated the Imbrian Period. Magnetic anomalies found in some Nectarian Period basins suggest that the Moon possessed a core dynamo magnetic field at that time. Relationship to Earth's geologic time scale Since little or no geological evidence on Earth exists from the time spanned by the Nectarian Period of the Moon, the Nectarian has been used by at least one notable scientific work as an unofficial subdivision of the terrestrial Hadean The Hadean ( ) is the first and oldest of the four geologic eons of Earth's history, starting with the planet's formation about 4.6 billion years ago (e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
