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Eratosthenian
The Eratosthenian period in the lunar geologic timescale runs from 3,200 million years ago to 1,100 million years ago. It is named after the crater Eratosthenes, which displays characteristics typical of craters of this age, including a surface that is not significantly eroded by subsequent impacts, but which also does not possess a ray system. The massive basaltic volcanism of the Imbrian period tapered off and ceased during this long span of lunar time. The youngest lunar lava flows identified from orbital images are tentatively placed near the end of this period. Its Earth equivalent consists of most of the Mesoarchean and Neoarchean eras (Archean eon), Paleoproterozoic and Mesoproterozoic eras (Proterozoic eon). Examples Other than Eratosthenes itself, examples of large Eratosthenian craters on the near side of the moon include Langrenus, Macrobius, Aristoteles, Hausen, Moretus, Pythagoras, Scoresby, Bullialdus, Plutarch, and Cavalerius. On the far side, examples incl ... [...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] |
Eratosthenes (crater)
Eratosthenes crater is a relatively deep lunar impact crater that lies on the boundary between the Mare Imbrium and Sinus Aestuum mare regions. It forms the western terminus of the Montes Apenninus mountain range. It is named after ancient Greek astronomer Eratosthenes of Cyrene, who estimated the circumference of the Earth, and the distance from the Earth to the Sun. Description The crater has a well-defined circular rim, terraced inner wall, central mountain peaks, an irregular floor, and an outer rampart of ejecta. It lacks a ray system of its own, but is overlain by rays from the prominent crater Copernicus to the south-west. The Eratosthenian period in the lunar geological timescale is named after this crater, though it does not define the start of this time period. The crater is believed to have been formed about 3.2 billion years ago. At low Sun-angles, this crater is prominent due to the shadow cast by the rim. When the Sun is directly overhead, however, Eratosthenes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kirkwood (crater)
Kirkwood is a well-formed lunar impact crater that is located on the far side of the Moon, on the northern hemisphere, approximately 68 kilometers in diameter. It lies just to the northeast of the crater Sommerfeld, and Hippocrates is located to the east-northeast. It was named after American astronomer Daniel Kirkwood. Description The perimeter of this crater is generally circular, with a few slight outward notches particularly to the southeast. It displays very little appearance of wear, and neither the interior nor the outer rampart are marked by any craters of note. The inner wall has slumped somewhat, and has formed a few terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk ...-like structures. The interior ejecta spreads a good way across the inner floor, covering n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finsen (crater)
Finsen is a lunar impact crater that is located in the southern hemisphere, on the Moon's far side. It is attached to the southeastern exterior of the walled plain Leibnitz, and the ejecta from Finsen covers the southeastern part of Leibnitz's interior floor. To the southwest of Finsen is another walled plain, Von Kármán, partly overlain by Leibnitz. This is a relatively young impact crater with well-defined features that have not been significantly eroded by subsequent impacts. The rim is circular but somewhat uneven along the edge, with outward protrusions along all sides except to the north and northwest. The inner wall has slumped in places, producing a sharp rim edge in the southern half. There are also a number of short terraces along the inner wall. The inner wall is wider to the north, and so the relatively level interior floor is offset slightly to the south. At the midpoint of the crater is a central peak formation, occupying an area of roughly 15 km. This cen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birkeland (lunar Crater)
Birkeland is a lunar impact crater that lies in the southern hemisphere on the far side of the Moon. This crater is attached to the central waist of the oddly shaped Van de Graaff crater formation, and may partly account for that crater's figure-8 shape. To the southeast is the large walled plain Leibnitz. This crater has not been significantly eroded, and the outer rim is well-defined with a well-terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk an ...d inner walls around much of the interior. The rim has a slight inward bulge along the north where it is attached to the Van de Graaff formation. The interior floor is relatively level, except in the southeast where there is some rough terrain. There is a central peak formation at the midpoint. Satellite craters By convention the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hamilton (crater)
Hamilton is a lunar impact crater that is located near the southeastern limb of the Moon. From the Earth this crater is viewed nearly from the edge, limiting the amount of detail that can be observed. It can also become hidden from sight due to libration, or brought into a more favorably viewing position. This crater is situated almost due east of the lava-flooded crater Oken, near the uneven Mare Australe. To the northeast of Hamilton, along the lunar limb, is the flooded crater Gum. Less than three crater diameters to the south is the flooded walled plain Lyot. This is a nearly circular crater, although the rim to the north is somewhat straightened. It has a well-formed edge that has not been noticeably degraded through impact erosion. There are terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olcott (crater)
Olcott is a relatively fresh crater on the far side of the Moon. It was named after American astronomer William Tyler Olcott. It lies to the south-southeast of the craters Seyfert and Polzunov, and to the north of Kostinskiy. This crater lacks any significant appearance of erosion from subsequent impacts, and its features are relatively well-defined. The rim edge is generally circular, with a slight outward bulge to the northeast and a larger bulge to the south. It has an outer rampart and some terraces and slumped edges along the inner wall. Several low ridges lie near the interior midpoint, with the western pair near the center and the eastern peaks offset towards the eastern rim. The satellite craters Olcott M and Olcott L form an overlapping pair along the southern outer rampart of Olcott, with the smaller member of the pair Olcott L overlapping Olcott M. The satellite crater Olcott E is partly overlain by the eastern rim of Olcott. Prior to naming in 1970 by the IAU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavalerius (crater)
Cavalerius is a prominent lunar impact crater that lies on the western edge of the Oceanus Procellarum lunar mare on the west part of the visible Moon. It nearly joins the northern rim of Hevelius to the south. The rim of Cavalerius is relatively high, rising to over 3 kilometers in places. There are clefts in the northern and southern parts of the rim and inner walls. Parts of the inner sides are terraced. The interior floor has mixed low hills and level areas. In the midpoint of the crater floor is a low central peak, with neighboring ridges to the north and east. Northeast of this crater is the site designated Planitia Descensus, the landing site of the Soviet Luna 9 Luna 9 (Луна-9), internal designation Ye-6 No.13, was an uncrewed space mission of the Soviet Union's Luna programme. On 3 February 1966, the Luna 9 spacecraft became the first spacecraft to achieve a survivable landing on a celestial body ... probe, the first vehicle to soft-land on the Moon. It lies am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutarch (crater)
Plutarch is a lunar impact crater that lies near the north-northeastern limb of the Moon, just to the south of the irregular crater Seneca. To the southeast is the flooded crater Cannon. The proximity of this crater to the limb causes it to appear foreshortened when viewed from the Earth, but it is actually a circular formation. This crater has a well-defined rim edge that is only slightly eroded. A small crater intrudes slightly into the southwestern rim, and another small crater lies near the south-southeastern rim. The inner wall is unusually wide in the southern half of the crater, with the narrowest section along the northern rim. There is some slumping and terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk an ...s formed along the inner sides, and a notable central peak near ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bullialdus (crater)
Bullialdus is a lunar impact crater located in the western part of the Mare Nubium. It was named after French astronomer Ismaël Boulliau. To the north by north-west is the broken-rimmed and lava-flooded crater Lubiniezky. South-west of Bullialdus lies the smaller crater König. The relatively isolated location of this crater serves to highlight its well-formed shape. Bullialdus has a high outer rim that is circular but observers have noted a slightly polygonal appearance. The inner walls are terraced and contain many signs of landslips. The outer ramparts are covered in a wide ''ejecta'' blanket that highlights a radial pattern of low ridges and valleys. In the center of the crater is a formation of several peaks and rises that climb to over a kilometer in height. A raised ridge runs from the peaks to the south-east, until finally merging with the inner wall. The floor of the crater is generally rough with many low rises. Overall it has a somewhat convex shape, bulging upward ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scoresby (crater)
Scoresby is a lunar impact crater that is located in the northern part of the Moon's near side. It is nearly attached to the crater Challis along the north-northwestern rim, and is located just to the north of the walled plain Meton. Due to its location, this crater appears highly foreshortened when viewed from the Earth, appearing elliptical in shape. It is, however, very nearly circular when seen from above. This formation has a sharp-edged outer wall that has not been significantly worn and is not marked by impacts. It has an outer rampart that extends outwards to nearly half a crater diameter, except where intersected by Challis in the north. The wide inner walls display an appearance of having been terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk ...d, but these have bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pythagoras (crater)
Pythagoras is a prominent impact crater located near the northwestern limb of the Moon. It lies just to the northwest of the somewhat larger Babbage. The crater has an oval appearance due to the oblique viewing angle. Only the western face of the interior can be viewed from the Earth, the other side being permanently out of sight. The well-preserved rim of Pythagoras has a wide terrace system, and a slight rampart around the exterior. Although generally circular, the crater outline has a hexagon In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...al form. The floor is flattened, but with an irregular, hilly surface. There is evidence of landslips around the periphery. In the center is a sharp, mountainous rise with a double peak that ascends 1.5 kilometers above the crater floor. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
