The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth. The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at 0.1654 g, with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density.
The South Pole–Aitken basin is an immense impact crater on the far side of the Moon. At roughly 2,500 km (1,600 mi) in diameter and between 6.2 and 8.2 km (3.9–5.1 mi) 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".
Amundsen is a large lunar impact crater located near the south pole of the Moon, named after the Norwegian explorer Roald Amundsen. It lies along the southern lunar limb, and so is viewed from the side by an observer on the Earth. To the northwest is the crater Scott, a formation of similar dimensions that is named for another Antarctic explorer. Nobile is attached to the western rim.
Copernicus is a lunar impact crater located in eastern Oceanus Procellarum. It was named after the astronomer Nicolaus Copernicus. It typifies craters that formed during the Copernican period in that it has a prominent ray system. It may have been created by debris from the breakup of the parent body of asteroid 495 Eulalia 800 million years ago.
Hermite is a lunar impact crater located along the northern lunar limb, close to the north pole of the Moon. Named for Charles Hermite, the crater was formed roughly 3.91 billion years ago. Hermite's southwestern edge is the coldest place currently known in the Solar System.
Posidonius is a lunar impact crater that is located on the north-eastern edge of Mare Serenitatis, to the south of Lacus Somniorum. It was named after ancient Greek philosopher and geographer Posidonius of Apamea. The crater Chacornac is attached to the southeast rim, and to the north is Daniell.
Shackleton is an impact crater that lies at the lunar south pole. The peaks along the crater's rim are exposed to almost continual sunlight, while the interior is perpetually in shadow. The low-temperature interior of this crater functions as a cold trap that may capture and freeze volatiles shed during comet impacts on the Moon. Measurements by the Lunar Prospector spacecraft showed higher than normal amounts of hydrogen within the crater, which may indicate the presence of water ice. The crater is named after Antarctic explorer Ernest Shackleton.
Peary is the closest large lunar impact crater to the lunar north pole. At this latitude the crater interior receives little sunlight, and portions of the southernmost region of the crater floor remain permanently cloaked in shadow. From the Earth the crater appears on the northern lunar limb, and is seen from the side.
Byrd is an irregular lunar impact crater that is located near the north pole of the Moon. The north rim of Byrd is nearly connected to the crater Peary, a formation that is adjacent to the pole. The smaller crater Gioja is attached to the remains of the southwest rim.
Plaskett is a prominent lunar impact crater that is located on the northern hemisphere on the far side of the Moon. It lies only a few hundred kilometers south of the lunar north pole, and the sunlight it receives is at a low angle. The large walled plain Rozhdestvenskiy is attached to the northeast rim of Plaskett, between the crater and the pole. To the south is the overlapping crater pair of Milankovic and Ricco.
Boltzmann is an old lunar impact crater that is located along the southern limb of the Moon, in the vicinity of the south pole. At this location the crater is viewed from the side from Earth, and so not much detail can be seen. It is located to the north of the walled plain Drygalski, and to the west of the crater Le Gentil.
Cabeus is a lunar impact crater that is located about 100 km (62 mi) from the south pole of the Moon. At this location the crater is seen obliquely from Earth, and it is almost perpetually in deep shadow due to lack of sunlight. Hence, not much detail can be seen of this crater, even from orbit. Through a telescope, this crater appears near the southern limb of the Moon, to the west of the crater Malapert and to the south-southwest of Newton.
A peak of eternal light (PEL) is a hypothetical point on the surface of an astronomical body that is always in sunlight. Such a peak must have high latitude, high elevation, and be on a body with very small axial tilt. The existence of such peaks was first postulated by Beer and Mädler in 1837. The pair said about the lunar polar mountains: "...many of these peaks have eternal sunshine". These polar peaks were later mentioned by Camille Flammarion in 1879, who speculated that there may exist pics de lumière éternelle at the poles of the Moon. PELs would be advantageous for space exploration and colonization due to the ability of an electrical device located there to receive solar power regardless of the time of day or day of the year, and the relatively stable temperature range.
Lunar water is water that is present on the Moon. Diffuse water molecules can persist at the Moon's sunlit surface, as discovered by NASA's SOFIA observatory in 2020. Gradually water vapor is decomposed by sunlight, leaving hydrogen and oxygen lost to outer space. Scientists have found water ice in the cold, permanently shadowed craters at the Moon's poles. Water molecules are also present in the extremely thin lunar atmosphere.
Nobile is a lunar impact crater that is located near the southern pole of the Moon. It lies to the south of the crater Scott, along the western rim of Amundsen. Between Nobile and the southern pole lie the smaller craters Shoemaker and Faustini.
The lunar south pole is the southernmost point on the Moon, at 90°S. It is of special interest to scientists because of the occurrence of water ice in permanently shadowed areas around it. The lunar south pole region features craters that are unique in that the near-constant sunlight does not reach their interior. Such craters are cold traps that contain a fossil record of hydrogen, water ice, and other volatiles dating from the early Solar System. In contrast, the lunar north pole region exhibits a much lower quantity of similarly sheltered craters.
Endeavour is an impact crater located in the Meridiani Planum extraterrestrial plain within the Margaritifer Sinus quadrangle (MC-19) region of the planet Mars. Endeavour is about 22 kilometers (14 mi) in diameter. Using Mars Reconnaissance Orbiter data, phyllosilicate-bearing outcrops have been detected along its rim. These minerals may have formed under wet conditions in a low-acidic environment during the early history of Mars. There are raised rim segments to the north, east, and southwest. The rim has become worn, rounded and degraded, with infilling of plains material in a manner similar to the Victoria crater.
Korolev is an ice-filled impact crater in the Mare Boreum quadrangle of Mars, located at 73° north latitude and 165° east longitude. It is 81.4 kilometres (50.6 mi) in diameter and contains about 2,200 cubic kilometres (530 cu mi) of water ice, comparable in volume to Great Bear Lake in northern Canada. The crater was named after Sergei Korolev (1907–1966), the head Soviet rocket engineer and designer during the Space Race in the 1950s and 1960s.
A permanently shadowed crater is a depression on a body in the Solar System within which lies a point that is always in darkness.
Pragyan was the rover of Chandrayaan-2, a lunar mission developed by the Indian Space Research Organisation (ISRO), that launched in July 2019. Pragyan was destroyed along with its lander, Vikram, when it crash-landed on the Moon in September 2019 and never got the chance to deploy.
