|384399 km (1.28 ls, 0.00257 AU)|
(29 d 12 h 44 min 2.9 s)
Average orbital speed
|Inclination||5.145° to the ecliptic[a]|
Regressing by one revolution in 18.61 years
Progressing by one
revolution in 8.85 years
|1737.4 km |
(0.2727 of Earth's)
|1738.1 km |
(0.2725 of Earth's)
|1736.0 km |
(0.2731 of Earth's)
|Circumference||10921 km (equatorial)|
|3.793×107 km2 |
(0.074 of Earth's)
|Volume||2.1958×1010 km3 |
(0.02 of Earth's)
|Mass||7.342×1022 kg |
(0.0123 of Earth's)
0.606 × Earth
|1.622 m/s2 (0.1654 g; 5.318 ft/s2)|
(8600 km/h; 5300 mph)
|27.321661 d (spin-orbit locked)|
Equatorial rotation velocity
North pole right ascension
North pole declination
|Surface absorbed dose rate||13.2 μGy/h|
|Surface equivalent dose rate||57.0 μSv/h|
|29.3 to 34.1 arcminutes[d]|
|Composition by volume|
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,[f] with a diameter about one-quarter that of Earth (comparable to the width of Australia). 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.
Orbiting Earth at an average distance of 384,400 km (238,900 mi), or about 30 times Earth's diameter, its gravitational influence very slowly lengthens Earth's day and is the main driver of Earth's tides. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period of 29.5 days, the amount of visible surface illuminated by the Sun varies from none up to 100%, resulting in lunar phases that form the basis for the months of a lunar calendar. The Moon is tidally locked to Earth, which means that the length of a full rotation of the Moon on its own axis causes its same side (the near side) to always face Earth, and the somewhat longer lunar day is the same as the synodic period. However, 59% of the total lunar surface can be seen from Earth through shifts in perspective due to libration.
The most widely accepted origin explanation posits that the Moon formed 4.51 billion years ago, not long after Earth, out of the debris from a giant impact between the planet and a hypothesized Mars-sized body called Theia. It then receded to a wider orbit because of tidal interaction with the Earth. The near side of the Moon is marked by dark volcanic maria ("seas"), which fill the spaces between bright ancient crustal highlands and prominent impact craters. Most of the large impact basins and mare surfaces were in place by the end of the Imbrian period, some three billion years ago. The lunar surface is relatively non-reflective, with a reflectance just slightly brighter than that of worn asphalt. However, because it has a large angular diameter, the full moon is the brightest celestial object in the night sky. The Moon's apparent size is nearly the same as that of the Sun, allowing it to cover the Sun almost completely during a total solar eclipse.
Both the Moon's prominence in Earth's sky and its regular cycle of phases have provided cultural references and influences for human societies throughout history. Such influences can be found in language, calendar systems, art, and mythology. The first artificial object to reach the Moon was the Soviet Union's Luna 2 uncrewed spacecraft in 1959; this was followed by the first successful soft landing by Luna 9 in 1966. The only human lunar missions to date have been those of the United States' Apollo program, which landed twelve men on the surface between 1969 and 1972. These and later uncrewed missions returned lunar rocks that have been used to develop a detailed geological understanding of the Moon's origins, internal structure, and subsequent history.
Names and etymology
The usual English proper name for Earth's natural satellite is simply Moon, with a capital M. The noun moon is derived from Old English mōna, which (like all its Germanic cognates) stems from Proto-Germanic *mēnōn, which in turn comes from Proto-Indo-European *mēnsis "month" (from earlier *mēnōt, genitive *mēneses) which may be related to the verb "measure" (of time).
Occasionally, the name Luna // is used in scientific writing and especially in science fiction to distinguish the Earth's moon from others, while in poetry "Luna" has been used to denote personification of the Moon. Cynthia // is another poetic name, though rare, for the Moon personified as a goddess, while Selene // (literally "Moon") is the Greek goddess of the Moon.
The usual English adjective pertaining to the Moon is "lunar", derived from the Latin word for the Moon, lūna. The adjective selenian //, derived from the Greek word for the Moon, σελήνη selēnē, and used to describe the Moon as a world rather than as an object in the sky, is rare, while its cognate selenic was originally a rare synonym but now nearly always refers to the chemical element selenium. The Greek word for the Moon does however provide us with the prefix seleno-, as in selenography, the study of the physical features of the Moon, as well as the element name selenium.
The Greek goddess of the wilderness and the hunt, Artemis, equated with the Roman Diana, one of whose symbols was the Moon and who was often regarded as the goddess of the Moon, was also called Cynthia, from her legendary birthplace on Mount Cynthus. These names – Luna, Cynthia and Selene – are reflected in technical terms for lunar orbits such as apolune, pericynthion and selenocentric.
The astronomical symbol for the Moon is a crescent, , for example in M☾ 'lunar mass' (also ML).
Lunar geologic timescale
Isotope dating of lunar samples suggests the Moon formed around 50 million years after the origin of the Solar System. Historically, several formation mechanisms have been proposed, but none satisfactorily explains the features of the Earth–Moon system. A fission of the Moon from Earth's crust through centrifugal force would require too great an initial rotation rate of Earth. Gravitational capture of a pre-formed Moon depends on an unfeasibly extended atmosphere of Earth to dissipate the energy of the passing Moon. A co-formation of Earth and the Moon together in the primordial accretion disk does not explain the depletion of metals in the Moon. None of these hypotheses can account for the high angular momentum of the Earth–Moon system.
The prevailing theory is that the Earth–Moon system formed after a giant impact of a Mars-sized body (named Theia) with the proto-Earth. The impact blasted material into orbit about the Earth and the material accreted and formed the Moon just beyond the Earth's Roche limit of ~2.56 R🜨.
Giant impacts are thought to have been common in the early Solar System. Computer simulations of giant impacts have produced results that are consistent with the mass of the lunar core and the angular momentum of the Earth–Moon system. These simulations show that most of the Moon derived from the impactor, rather than the proto-Earth. However, more recent simulations suggest a larger fraction of the Moon derived from the proto-Earth. Other bodies of the inner Solar System such as Mars and Vesta have, according to meteorites from them, very different oxygen and tungsten isotopic compositions compared to Earth. However, Earth and the Moon have nearly identical isotopic compositions. The isotopic equalization of the Earth-Moon system might be explained by the post-impact mixing of the vaporized material that formed the two, although this is debated.
The impact would have released enough energy to liquefy both the ejecta and the Earth's crust, forming a magma ocean. The liquefied ejecta could have then re-accreted into the Earth–Moon system. Similarly, the newly formed Moon would have had its own lunar magma ocean; its depth is estimated from about 500 km (300 miles) to 1,737 km (1,079 miles).
While the giant-impact theory explains many lines of evidence, some questions are still unresolved, most of which involve the Moon's composition.[example needed]Above a high resolution threshold for simulations, a study published in 2022 finds that giant impacts can immediately place a satellite with similar mass and iron content to the Moon into orbit far outside Earth's Roche limit. Even satellites that initially pass within the Roche limit can reliably and predictably survive, by being partially stripped and then torqued onto wider, stable orbits.
After the Moon's formation the Moon settled in orbit around Earth much closer than today, making both bodies appear much larger in each's sky and causing on both more frequent and stronger eclipses and tidal effects. Since then, due to tidal acceleration, the Moon's orbit around Earth has become significantly larger as well as longer, tidally locking the so-called lunar near side, always facing Earth with this same side.
The post formation cooled lunar surface has been shaped by large and many small impact events, retaining a broadly cratered landscape of all ages, as well as by volcanic activity, producing the prominent lunar maria. Volcanically active until 1.2 billion years ago, most of the Moon's mare basalts erupted during the Imbrian period, 3.3–3.7 billion years ago, though some being as young as 1.2 billion years and some as old as 4.2 billion years. The causes for the eruption of mare basalts, particularly their uneven occurrence on mainly the near-side, like the lunar highlands on the far side, has been an unresolved issue due to differing explanations. One explanation suggests that large meteorites were hitting the Moon in its early history leaving large craters which then were filled with lava. Other explanations suggest processes of lunar volcanism.
The Moon is a very slightly scalene ellipsoid due to tidal stretching, with its long axis displaced 30° from facing the Earth, due to gravitational anomalies from impact basins. Its shape is more elongated than current tidal forces can account for. This 'fossil bulge' indicates that the Moon solidified when it orbited at half its current distance to the Earth, and that it is now too cold for its shape to adjust to its orbit.
Size and mass
The Moon is by size and mass the fifth largest natural satellite of the Solar System, categorizeable as one of its planetary-mass moons, making it a satellite planet under the geophysical definitions of the term. It is smaller than Mercury and considerably larger than the largest dwarf planet of the Solar System, Pluto. While the minor-planet moon Charon of the Pluto-Charon system is larger relative to Pluto,[f] the Moon is the largest natural satellite of the Solar System relative to their primary planets.[g]
The Moon's diameter is about 3,500 km, more than a quarter of Earth's, with the face of the Moon comparable to the width of Australia. The whole surface area of the Moon is about 38 million square kilometers, slightly less than the area of the Americas (North and South America).
The Moon's mass is 1/81 of Earth's, being the second densest among the planetary moons, and having the second highest surface gravity, after Io, at 0.1654 g and an escape velocity of 2.38 km/s (8600 km/h; 5300 mph).
The Moon is a differentiated body that was initially in hydrostatic equilibrium but has since departed from this condition. It has a geochemically distinct crust, mantle, and core. The Moon has a solid iron-rich inner core with a radius possibly as small as 240 kilometres (150 mi) and a fluid outer core primarily made of liquid iron with a radius of roughly 300 kilometres (190 mi). Around the core is a partially molten boundary layer with a radius of about 500 kilometres (310 mi). This structure is thought to have developed through the fractional crystallization of a global magma ocean shortly after the Moon's formation 4.5 billion years ago.
Crystallization of this magma ocean would have created a mafic mantle from the precipitation and sinking of the minerals olivine, clinopyroxene, and orthopyroxene; after about three-quarters of the magma ocean had crystallised, lower-density plagioclase minerals could form and float into a crust atop. The final liquids to crystallise would have been initially sandwiched between the crust and mantle, with a high abundance of incompatible and heat-producing elements. Consistent with this perspective, geochemical mapping made from orbit suggests a crust of mostly anorthosite. The Moon rock samples of the flood lavas that erupted onto the surface from partial melting in the mantle confirm the mafic mantle composition, which is more iron-rich than that of Earth. The crust is on average about 50 kilometres (31 mi) thick.
The Moon is the second-densest satellite in the Solar System, after Io. However, the inner core of the Moon is small, with a radius of about 350 kilometres (220 mi) or less, around 20% of the radius of the Moon. Its composition is not well understood, but is probably metallic iron alloyed with a small amount of sulfur and nickel; analyses of the Moon's time-variable rotation suggest that it is at least partly molten. The pressure at the lunar core is estimated to be 5 GPa (49,000 atm).
Magnetic and gravitational fields
The Moon has an external magnetic field of less than 0.2 nanoteslas, or less than one hundred thousandth that of Earth. The Moon does not currently have a global dipolar magnetic field and only has crustal magnetization likely acquired early in its history when a dynamo was still operating. However, early in its history, 4 billion years ago, its magnetic field strength was likely close to that of Earth today. This early dynamo field apparently expired by about one billion years ago, after the lunar core had completely crystallized. Theoretically, some of the remnant magnetization may originate from transient magnetic fields generated during large impacts through the expansion of plasma clouds. These clouds are generated during large impacts in an ambient magnetic field. This is supported by the location of the largest crustal magnetizations situated near the antipodes of the giant impact basins.
The Moon's gravitational field is not uniform. The details of the gravitational field have been measured through tracking the Doppler shift of radio signals emitted by orbiting spacecraft. The main lunar gravity features are mascons, large positive gravitational anomalies associated with some of the giant impact basins, partly caused by the dense mare basaltic lava flows that fill those basins. The anomalies greatly influence the orbit of spacecraft about the Moon. There are some puzzles: lava flows by themselves cannot explain all of the gravitational signature, and some mascons exist that are not linked to mare volcanism.
On average the Moon's surface gravity is 1.62 m/s2 (0.1654 g; 5.318 ft/s2), about half of the surface gravity of Mars and about a sixth of Earth's. The surface of the Moon, having a surface pressure of 10−10 Pa, lacks any significant atmosphere to moderate the extreme conditions of the surface.
Ionizing radiation from cosmic rays, the Sun and the resulting neutron radiation produce radiation levels on average of 1,369 microsieverts per day, which is about 2-3 times more than on the International Space Station at about 400 km above Earth in orbit, 5-10 times more than during a trans-Atlantic flight, 200 times more than on Earth's surface. For further comparison radiation on a flight to Mars is about 1.84 millisieverts per day and on Mars 0.64 millisieverts per day.
The Moon's axial tilt with respect to the ecliptic is only 1.5427°, much less than the 23.44° of Earth. Because of this small tilt, the Moon's solar illumination varies much less with season than on Earth and it allows for the existence of some peaks of eternal light at the Moon's north pole, at the rim of the crater Peary.
The surface is exposed to drastic temperature differences ranging from 140 °C to −171 °C depending on the solar irradiance. Because of the lack of atmosphere, temperatures of different areas vary particularly upon whether they are in sunlight or shadow, making topographical details play a decisive role on local surface temperatures. Parts of many craters, particularly the bottoms of many polar craters, are permanently shadowed, these "craters of eternal darkness" have extremely low temperatures. The Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to the winter solstice in the north polar crater Hermite. This is the coldest temperature in the Solar System ever measured by a spacecraft, colder even than the surface of Pluto.
These extreme conditions for example are considered making it unlikely for spacecrafts to harbor bacterial spores at the Moon longer than just one lunar orbit.
The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 tonnes (9.8 long tons; 11 short tons). The surface pressure of this small mass is around 3 × 10−15 atm (0.3 nPa); it varies with the lunar day. Its sources include outgassing and sputtering, a product of the bombardment of lunar soil by solar wind ions. Elements that have been detected include sodium and potassium, produced by sputtering (also found in the atmospheres of Mercury and Io); helium-4 and neon from the solar wind; and argon-40, radon-222, and polonium-210, outgassed after their creation by radioactive decay within the crust and mantle. The absence of such neutral species (atoms or molecules) as oxygen, nitrogen, carbon, hydrogen and magnesium, which are present in the regolith, is not understood. Water vapor has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith. These gases either return into the regolith because of the Moon's gravity or are lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind's magnetic field.
Studies of Moon magma samples retrieved by the Apollo missions demonstrate that the Moon had once possessed a relatively thick atmosphere for a period of 70 million years between 3 and 4 billion years ago. This atmosphere, sourced from gases ejected from lunar volcanic eruptions, was twice the thickness of that of present-day Mars. The ancient lunar atmosphere was eventually stripped away by solar winds and dissipated into space.
A permanent Moon dust cloud exists around the Moon, generated by small particles from comets. Estimates are 5 tons of comet particles strike the Moon's surface every 24 hours, resulting in the ejection of dust particles. The dust stays above the Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. On average, 120 kilograms of dust are present above the Moon, rising up to 100 kilometers above the surface. Dust counts made by LADEE's Lunar Dust EXperiment (LDEX) found particle counts peaked during the Geminid, Quadrantid, Northern Taurid, and Omicron Centaurid meteor showers, when the Earth, and Moon pass through comet debris. The lunar dust cloud is asymmetric, being more dense near the boundary between the Moon's dayside and nightside.
The topography of the Moon has been measured with laser altimetry and stereo image analysis. Its most extensive topographic feature is the giant far-side South Pole–Aitken basin, some 2,240 km (1,390 mi) in diameter, the largest crater on the Moon and the second-largest confirmed impact crater in the Solar System. At 13 km (8.1 mi) deep, its floor is the lowest point on the surface of the Moon. The highest elevations of the Moon's surface are located directly to the northeast, which might have been thickened by the oblique formation impact of the South Pole–Aitken basin. Other large impact basins such as Imbrium, Serenitatis, Crisium, Smythii, and Orientale possess regionally low elevations and elevated rims. The far side of the lunar surface is on average about 1.9 km (1.2 mi) higher than that of the near side.
The discovery of fault scarp cliffs suggest that the Moon has shrunk by about 90 metres (300 ft) within the past billion years. Similar shrinkage features exist on Mercury. Mare Frigoris, a basin near the north pole long assumed to be geologically dead, has cracked and shifted. Since the Moon doesn't have tectonic plates, its tectonic activity is slow and cracks develop as it loses heat.
The main features visible from Earth by the naked eye are dark and relatively featureless lunar plains called maria (singular mare; Latin for "seas", as they were once believed to be filled with water) are vast solidified pools of ancient basaltic lava. Although similar to terrestrial basalts, lunar basalts have more iron and no minerals altered by water. The majority of these lava deposits erupted or flowed into the depressions associated with impact basins. Several geologic provinces containing shield volcanoes and volcanic domes are found within the near side "maria".
Almost all maria are on the near side of the Moon, and cover 31% of the surface of the near side compared with 2% of the far side. This is likely due to a concentration of heat-producing elements under the crust on the near side, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt. Most of the Moon's mare basalts erupted during the Imbrian period, 3.3–3.7 billion years ago, though some being as young as 1.2 billion years and as old as 4.2 billion years.
In 2006, a study of Ina, a tiny depression in Lacus Felicitatis, found jagged, relatively dust-free features that, because of the lack of erosion by infalling debris, appeared to be only 2 million years old. Moonquakes and releases of gas indicate continued lunar activity. Evidence of recent lunar volcanism has been identified at 70 irregular mare patches, some less than 50 million years old. This raises the possibility of a much warmer lunar mantle than previously believed, at least on the near side where the deep crust is substantially warmer because of the greater concentration of radioactive elements. Evidence has been found for 2–10 million years old basaltic volcanism within the crater Lowell, inside the Orientale basin. Some combination of an initially hotter mantle and local enrichment of heat-producing elements in the mantle could be responsible for prolonged activities on the far side in the Orientale basin.
The lighter-colored regions of the Moon are called terrae, or more commonly highlands, because they are higher than most maria. They have been radiometrically dated to having formed 4.4 billion years ago, and may represent plagioclase cumulates of the lunar magma ocean. In contrast to Earth, no major lunar mountains are believed to have formed as a result of tectonic events.
The concentration of maria on the near side likely reflects the substantially thicker crust of the highlands of the Far Side, which may have formed in a slow-velocity impact of a second moon of Earth a few tens of millions of years after the Moon's formation. Alternatively, it may be a consequence of asymmetrical tidal heating when the Moon was much closer to the Earth.
A major geologic process that has affected the Moon's surface is impact cratering, with craters formed when asteroids and comets collide with the lunar surface. There are estimated to be roughly 300,000 craters wider than 1 km (0.6 mi) on the Moon's near side. The lunar geologic timescale is based on the most prominent impact events, including Nectaris, Imbrium, and Orientale; structures characterized by multiple rings of uplifted material, between hundreds and thousands of kilometers in diameter and associated with a broad apron of ejecta deposits that form a regional stratigraphic horizon. The lack of an atmosphere, weather, and recent geological processes mean that many of these craters are well-preserved. Although only a few multi-ring basins have been definitively dated, they are useful for assigning relative ages. Because impact craters accumulate at a nearly constant rate, counting the number of craters per unit area can be used to estimate the age of the surface. The radiometric ages of impact-melted rocks collected during the Apollo missions cluster between 3.8 and 4.1 billion years old: this has been used to propose a Late Heavy Bombardment period of increased impacts.
High-resolution images from the Lunar Reconnaissance Orbiter in the 2010s show a contemporary crater-production rate significantly higher than was previously estimated. A secondary cratering process caused by distal ejecta is thought to churn the top two centimeters of regolith on a timescale of 81,000 years. This rate is 100 times faster than the rate computed from models based solely on direct micrometeorite impacts.
Lunar swirls are enigmatic features found across the Moon's surface. They are characterized by a high albedo, appear optically immature (i.e. the optical characteristics of a relatively young regolith), and often have a sinuous shape. Their shape is often accentuated by low albedo regions that wind between the bright swirls. They are located in places with enhanced surface magnetic fields and many are located at the antipodal point of major impacts. Well known swirls include the Reiner Gamma feature and Mare Ingenii. They are hypothesized to be areas that have been partially shielded from the solar wind, resulting in slower space weathering.
Blanketed on top of the Moon's crust is a highly comminuted (broken into ever smaller particles) and impact gardened mostly gray surface layer called regolith, formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has a texture resembling snow and a scent resembling spent gunpowder. The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from 10–15 m (33–49 ft) in the highlands and 4–5 m (13–16 ft) in the maria.
Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometers thick.
Presence of water
Liquid water cannot persist on the lunar surface. When exposed to solar radiation, water quickly decomposes through a process known as photodissociation and is lost to space. However, since the 1960s, scientists have hypothesized that water ice may be deposited by impacting comets or possibly produced by the reaction of oxygen-rich lunar rocks, and hydrogen from solar wind, leaving traces of water which could possibly persist in cold, permanently shadowed craters at either pole on the Moon. Computer simulations suggest that up to 14,000 km2 (5,400 sq mi) of the surface may be in permanent shadow. The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation as a cost-effective plan; the alternative of transporting water from Earth would be prohibitively expensive.
In years since, signatures of water have been found to exist on the lunar surface. In 1994, the bistatic radar experiment located on the Clementine spacecraft, indicated the existence of small, frozen pockets of water close to the surface. However, later radar observations by Arecibo, suggest these findings may rather be rocks ejected from young impact craters. In 1998, the neutron spectrometer on the Lunar Prospector spacecraft showed that high concentrations of hydrogen are present in the first meter of depth in the regolith near the polar regions. Volcanic lava beads, brought back to Earth aboard Apollo 15, showed small amounts of water in their interior.
The 2008 Chandrayaan-1 spacecraft has since confirmed the existence of surface water ice, using the on-board Moon Mineralogy Mapper. The spectrometer observed absorption lines common to hydroxyl, in reflected sunlight, providing evidence of large quantities of water ice, on the lunar surface. The spacecraft showed that concentrations may possibly be as high as 1,000 ppm. Using the mapper's reflectance spectra, indirect lighting of areas in shadow confirmed water ice within 20° latitude of both poles in 2018. In 2009, LCROSS sent a 2,300 kg (5,100 lb) impactor into a permanently shadowed polar crater, and detected at least 100 kg (220 lb) of water in a plume of ejected material. Another examination of the LCROSS data showed the amount of detected water to be closer to 155 ± 12 kg (342 ± 26 lb).
In May 2011, 615–1410 ppm water in melt inclusions in lunar sample 74220 was reported, the famous high-titanium "orange glass soil" of volcanic origin collected during the Apollo 17 mission in 1972. The inclusions were formed during explosive eruptions on the Moon approximately 3.7 billion years ago. This concentration is comparable with that of magma in Earth's upper mantle. Although of considerable selenological interest, this insight does not mean that water is easily available since the sample originated many kilometers below the surface, and the inclusions are so difficult to access that it took 39 years to find them with a state-of-the-art ion microprobe instrument.
Analysis of the findings of the Moon Mineralogy Mapper (M3) revealed in August 2018 for the first time "definitive evidence" for water-ice on the lunar surface. The data revealed the distinct reflective signatures of water-ice, as opposed to dust and other reflective substances. The ice deposits were found on the North and South poles, although it is more abundant in the South, where water is trapped in permanently shadowed craters and crevices, allowing it to persist as ice on the surface since they are shielded from the sun.
In October 2020, astronomers reported detecting molecular water on the sunlit surface of the Moon by several independent spacecraft, including the Stratospheric Observatory for Infrared Astronomy (SOFIA).
The Earth and the Moon form the Earth-Moon satellite system with a shared center of mass, or barycentre. This barycentre stays located at all times 1,700 km (1,100 mi) (about a quarter of Earth's radius) beneath the Earth's surface, making the Moon seemingly orbit the Earth.
The orbital eccentricity, giving ovalness of the orbit, is 0.055. The Lunar distance, or the semi-major axis of the geocentric lunar orbit, is approximately 400,000 km, which is a quarter of a million miles or 1.28 light-seconds, and a unit of measure in astronomy. This is not to be confused with the instantaneous Earth–Moon distance, or distance to the Moon, the momentanous distance from the center of Earth to the center of the Moon.
The Moon makes a complete orbit around Earth with respect to the fixed stars, its sidereal period, about once every 27.3 days,[h]. However, because the Earth-Moon system moves at the same time in its orbit around the Sun, it takes slightly longer, 29.5 days;[i], to return at the same lunar phase, completing a full cycle, as seen from Earth. This synodic period or synodic month is commonly known as the lunar month and is equal to the length of the solar day on the Moon.
Due to tidal locking, the Moon has a 1:1 spin–orbit resonance. This rotation–orbit ratio makes the Moon's orbital periods around Earth equal to its corresponding rotation periods. This is the reason for only one side of the Moon, its so-called near side, being visible from Earth. That said, while the movement of the Moon is in resonance, it still is not without nuances such as libration, resulting in slightly changing perspectives, making over time and location on Earth about 59% of the Moon's surface visible from Earth.
Unlike most satellites of other planets, the Moon's orbital plane is closer to the ecliptic plane than to the planet's equatorial plane. The Moon's orbit is subtly perturbed by the Sun and Earth in many small, complex and interacting ways. For example, the plane of the Moon's orbit gradually rotates once every 18.61 years, which affects other aspects of lunar motion. These follow-on effects are mathematically described by Cassini's laws.
The gravitational attraction that Earth and the Moon (as well as the Sun) exert on each other manifests in a slightly greater attraction on the sides of closest to each other, resulting in tidal forces. Ocean tides are the most widely experienced result of this, but tidal forces considerably affect also other mechanics of Earth, as well as the Moon and their system.
The lunar solid crust experiences tides of around 10 cm (4 in) amplitude over 27 days, with three components: a fixed one due to Earth, because they are in synchronous rotation, a variable tide due to orbital eccentricity and inclination, and a small varying component from the Sun. The Earth-induced variable component arises from changing distance and libration, a result of the Moon's orbital eccentricity and inclination (if the Moon's orbit were perfectly circular and un-inclined, there would only be solar tides). According to recent research, scientists suggest that the Moon's influence on the Earth may contribute to maintaining Earth's magnetic field.
The cumulative effects of stress built up by these tidal forces produces moonquakes. Moonquakes are much less common and weaker than are earthquakes, although moonquakes can last for up to an hour – significantly longer than terrestrial quakes – because of scattering of the seismic vibrations in the dry fragmented upper crust. The existence of moonquakes was an unexpected discovery from seismometers placed on the Moon by Apollo astronauts from 1969 through 1972.
The most commonly known effect of tidal forces are elevated sea levels called ocean tides. While the Moon exerts most of the tidal forces, the Sun also exerts tidal forces and therefore contributes to the tides as much as 40% of the Moon's tidal force; producing in interplay the spring and neap tides.
The tides are two bulges in the Earth's oceans, one on the side facing the Moon and the other on the side opposite. As the Earth rotates on its axis, one of the ocean bulges (high tide) is held in place "under" the Moon, while another such tide is opposite. As a result, there are two high tides, and two low tides in about 24 hours. Since the Moon is orbiting the Earth in the same direction of the Earth's rotation, the high tides occur about every 12 hours and 25 minutes; the 25 minutes is due to the Moon's time to orbit the Earth.
If the Earth were a water world (one with no continents) it would produce a tide of only one meter, and that tide would be very predictable, but the ocean tides are greatly modified by other effects:
- the frictional coupling of water to Earth's rotation through the ocean floors
- the inertia of water's movement
- ocean basins that grow shallower near land
- the sloshing of water between different ocean basins
As a result, the timing of the tides at most points on the Earth is a product of observations that are explained, incidentally, by theory.
Delays in the tidal peaks of both ocean and solid-body tides cause torque in opposition to the Earth's rotation. This "drains" angular momentum and rotational kinetic energy from Earth's rotation, slowing the Earth's rotation. That angular momentum, lost from the Earth, is transferred to the Moon in a process known as tidal acceleration, which lifts the Moon into a higher orbit while lowering orbital speed around the Earth.
Thus the distance between Earth and Moon is increasing, and the Earth's rotation is slowing in reaction. Measurements from laser reflectors left during the Apollo missions (lunar ranging experiments) have found that the Moon's distance increases by 38 mm (1.5 in) per year (roughly the rate at which human fingernails grow). Atomic clocks show that Earth's day lengthens by about 17 microseconds every year, slowly increasing the rate at which UTC is adjusted by leap seconds.
This tidal drag makes the rotation of Earth and the orbital period of the Moon very slowly match. This matching first results in tidally locking the lighter body of the orbital system, as already the case with the Moon. Eventually, after 50 billion years, also the Earth would be made to always face the Moon with the same side. This would complete the mutual tidal locking of Earth and the Moon, matching the length of Earth's day to the then also significantly increased lunar month and the Moon's day, and suspending the Moon over one meridian (comparable to the Pluto-Charon system). However, the Sun will become a red giant engulfing the Earth-Moon system long before the latter occurs.
Position and appearance
The tidally locked synchronous rotation of the Moon as it orbits the Earth results in it always keeping nearly the same face turned towards the planet. The side of the Moon that faces Earth is called the near side, and the opposite the far side. The far side is often inaccurately called the "dark side", but it is in fact illuminated as often as the near side: once every 29.5 Earth days. During dark moon to new moon, the near side is dark.
The Moon originally rotated at a faster rate, but early in its history its rotation slowed and became tidally locked in this orientation as a result of frictional effects associated with tidal deformations caused by Earth. With time, the energy of rotation of the Moon on its axis was dissipated as heat, until there was no rotation of the Moon relative to Earth. In 2016, planetary scientists using data collected on the 1998-99 NASA Lunar Prospector mission, found two hydrogen-rich areas (most likely former water ice) on opposite sides of the Moon. It is speculated that these patches were the poles of the Moon billions of years ago before it was tidally locked to Earth.
View from Earth
The Moon's highest altitude at culmination varies by its lunar phase, or more correctly its orbital position, and time of the year, or more correctly the position of the Earth's axis. The full moon is highest in the sky during winter and lowest during summer (for each hemisphere respectively), with its altitude changing towards dark moon to the opposite.
At the North and South Poles the Moon is 24 hours above the horizon for two weeks every tropical month (about 27.3 days), comparable to the polar day of the tropical year. Zooplankton in the Arctic use moonlight when the Sun is below the horizon for months on end.
The apparent orientation of the Moon depends on its position in the sky and the hemisphere of the Earth from which it is being viewed. In the northern hemisphere it is seen upside down compared to the view in the southern hemisphere. Sometimes the "horns" of a crescent moon appear to be pointing more upwards than sideways. This phenomenon is called a wet moon and occurs more frequently in the tropics.
The distance between the Moon and Earth varies from around 356,400 km (221,500 mi) to 406,700 km (252,700 mi) at perigee (closest) and apogee (farthest), respectively, making the Moon's apparent size fluctuate. On sverage the Moon's angular diameter is about 0.52° (on average) in the sky, roughly the same apparent size as the Sun (see § Eclipses). Additionally when close to the horizon a purely psychological effect, known as the Moon illusion, makes the Moon appear larger.
Albedo and colour
The Moon has an exceptionally low albedo, giving it a reflectance that is slightly brighter than that of worn asphalt. Despite this, it is the brightest object in the sky after the Sun.[j] This is due partly to the brightness enhancement of the opposition surge; the Moon at quarter phase is only one-tenth as bright, rather than half as bright, as at full moon. Additionally, color constancy in the visual system recalibrates the relations between the colors of an object and its surroundings, and because the surrounding sky is comparatively dark, the sunlit Moon is perceived as a bright object. The edges of the full moon seem as bright as the center, without limb darkening, because of the reflective properties of lunar soil, which retroreflects light more towards the Sun than in other directions. The Moon's color depends on the light the Moon reflects, which in turn depends on the Moon's surface and its features, having for example large darker regions. In general the lunar surface reflects a brown-tinged gray light.
Viewed from Earth the air filters the reflected light, at times giving it a red colour depending on the angle of the Moon in the sky and thickness of the atmosphere, or a blue tinge depending on the particles in the air, as in cases of volcanic particles. The terms blood moon and blue moon do not necessarily refer to circumstances of red or blue moonlight, but are rather particular cultural references such as particular full moons of a year.
There has been historical controversy over whether observed features on the Moon's surface change over time. Today, many of these claims are thought to be illusory, resulting from observation under different lighting conditions, poor astronomical seeing, or inadequate drawings. However, outgassing does occasionally occur and could be responsible for a minor percentage of the reported lunar transient phenomena. Recently, it has been suggested that a roughly 3 km (1.9 mi) diameter region of the lunar surface was modified by a gas release event about a million years ago.
Illumination and phases
Half of the Moon's surface is always illuminated by the Sun (except during a lunar eclipse). Earth also reflects light onto the Moon, observable at times as Earthlight when it is again reflected back to Earth from areas of the near side of the Moon that are not illuminated by the Sun.
With the different positions of the Moon, different areas of it are illuminated by the Sun. This illumination of different lunar areas, as viewed from Earth, produces the different lunar phases during the synodic month. A phase is equal to the area of the visible lunar sphere that is illuminated by the Sun. This area or degree of illumination is given by , where is the elongation (i.e., the angle between Moon, the observer on Earth, and the Sun).
On 14 November 2016, the Moon was at full phase closer to Earth than it had been since 1948. It was 14% closer and larger than its farthest position in apogee. This closest point coincided within an hour of a full moon, and it was 30% more luminous than when at its greatest distance because of its increased apparent diameter, which made it a particularly notable example of a "supermoon".
When the actual reduction is 1.00 / 1.30, or about 0.770, the perceived reduction is about 0.877, or 1.00 / 1.14. This gives a maximum perceived increase of 14% between apogee and perigee moons of the same phase.
Eclipses only occur when the Sun, Earth, and Moon are all in a straight line (termed "syzygy"). Solar eclipses occur at new moon, when the Moon is between the Sun and Earth. In contrast, lunar eclipses occur at full moon, when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both total (with the Moon appearing larger than the Sun) and annular (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye. Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. As it evolves toward becoming a red giant, the size of the Sun, and its apparent diameter in the sky, are slowly increasing.[k] The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.
Because the Moon's orbit around Earth is inclined by about 5.145° (5° 9') to the orbit of Earth around the Sun, eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes. The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by Earth, is described by the saros, which has a period of approximately 18 years.
Because the Moon continuously blocks the view of a half-degree-wide circular area of the sky,[l] the related phenomenon of occultation occurs when a bright star or planet passes behind the Moon and is occulted: hidden from view. In this way, a solar eclipse is an occultation of the Sun. Because the Moon is comparatively close to Earth, occultations of individual stars are not visible everywhere on the planet, nor at the same time. Because of the precession of the lunar orbit, each year different stars are occulted.
History of exploration and human presence
Pre-telescopic observation (before 1609)
It is believed by some that 20–30,000 year old tally sticks, were used to observe the phases of the Moon, keeping time using the waxing and waning of the Moon's phases. One of the earliest-discovered possible depictions of the Moon is a 5000-year-old rock carving Orthostat 47 at Knowth, Ireland.
The ancient Greek philosopher Anaxagoras (d. 428 BC) reasoned that the Sun and Moon were both giant spherical rocks, and that the latter reflected the light of the former.: 227 Elsewhere in the 5th century BC to 4th century BC, Babylonian astronomers had recorded the 18-year Saros cycle of lunar eclipses, and Indian astronomers had described the Moon's monthly elongation. The Chinese astronomer Shi Shen (fl. 4th century BC) gave instructions for predicting solar and lunar eclipses.: 411
In Aristotle's (384–322 BC) description of the universe, the Moon marked the boundary between the spheres of the mutable elements (earth, water, air and fire), and the imperishable stars of aether, an influential philosophy that would dominate for centuries. Archimedes (287–212 BC) designed a planetarium that could calculate the motions of the Moon and other objects in the Solar System. In the 2nd century BC, Seleucus of Seleucia correctly theorized that tides were due to the attraction of the Moon, and that their height depends on the Moon's position relative to the Sun. In the same century, Aristarchus computed the size and distance of the Moon from Earth, obtaining a value of about twenty times the radius of Earth for the distance.
Although the Chinese of the Han Dynasty believed the Moon to be energy equated to qi, their 'radiating influence' theory recognized that the light of the Moon was merely a reflection of the Sun, and Jing Fang (78–37 BC) noted the sphericity of the Moon.: 413–414 Ptolemy (90–168 AD) greatly improved on the numbers of Aristarchus, calculating the values of a mean distance of 59 times Earth's radius and a diameter of 0.292 Earth diameters were close to the correct values of about 60 and 0.273 respectively. In the 2nd century AD, Lucian wrote the novel A True Story, in which the heroes travel to the Moon and meet its inhabitants. In 499 AD, the Indian astronomer Aryabhata mentioned in his Aryabhatiya that reflected sunlight is the cause of the shining of the Moon. The astronomer and physicist Alhazen (965–1039) found that sunlight was not reflected from the Moon like a mirror, but that light was emitted from every part of the Moon's sunlit surface in all directions. Shen Kuo (1031–1095) of the Song dynasty created an allegory equating the waxing and waning of the Moon to a round ball of reflective silver that, when doused with white powder and viewed from the side, would appear to be a crescent.: 415–416
Telescopic exploration (1609-1959)
In 1609, Galileo Galilei used an early telescope to make drawings of the Moon for his book Sidereus Nuncius, and deduced that it was not smooth but had mountains and craters. Thomas Harriot had made, but not published such drawings a few months earlier.
Telescopic mapping of the Moon followed: later in the 17th century, the efforts of Giovanni Battista Riccioli and Francesco Maria Grimaldi led to the system of naming of lunar features in use today. The more exact 1834–1836 Mappa Selenographica of Wilhelm Beer and Johann Heinrich Mädler, and their associated 1837 book Der Mond, the first trigonometrically accurate study of lunar features, included the heights of more than a thousand mountains, and introduced the study of the Moon at accuracies possible in earthly geography. Lunar craters, first noted by Galileo, were thought to be volcanic until the 1870s proposal of Richard Proctor that they were formed by collisions. This view gained support in 1892 from the experimentation of geologist Grove Karl Gilbert, and from comparative studies from 1920 to the 1940s, leading to the development of lunar stratigraphy, which by the 1950s was becoming a new and growing branch of astrogeology.
First missions to the Moon (1959–1990)
After World War II the first launch systems were developed and by the end of the 1950s they reached capabilities that allowed the Soviet Union and the United States to launch spacecrafts into space. The Cold War fueled a closely followed development of launch systems by the two states, resulting in the so-called Space Race and its later phase the Moon Race, accelerating efforts and interest in exploration of the Moon.
After the first spaceflight of Sputnik 1 in 1957 during International Geophysical Year the spacecrafts of the Soviet Union's Luna program were the first to accomplish a number of goals. Following three unnamed failed missions in 1958, the first human-made object Luna 1 escaped Earth's gravity and passed near the Moon in 1959. Later that year the first human-made object Luna 2 reached the Moon's surface by intentionally impacting. By the end of the year Luna 3 reached as the first human-made object the normally occluded far side of the Moon, taking the first photographs of it. The first spacecraft to perform a successful lunar soft landing was Luna 9 and the first vehicle to orbit the Moon was Luna 10, both in 1966.
Following President John F. Kennedy's 1961 commitment to a manned Moon landing before the end of the decade, the United States, under NASA leadership, launched a series of uncrewed probes to develop an understanding of the lunar surface in preparation for human missions: the Jet Propulsion Laboratory's Ranger program, the Lunar Orbiter program and the Surveyor program. The crewed Apollo program was developed in parallel; after a series of uncrewed and crewed tests of the Apollo spacecraft in Earth orbit, and spurred on by a potential Soviet lunar human landing, in 1968 Apollo 8 made the first human mission to lunar orbit. The subsequent landing of the first humans on the Moon in 1969 is seen by many as the culmination of the Space Race.
Neil Armstrong became the first person to walk on the Moon as the commander of the American mission Apollo 11 by first setting foot on the Moon at 02:56 UTC on 21 July 1969. An estimated 500 million people worldwide watched the transmission by the Apollo TV camera, the largest television audience for a live broadcast at that time. The Apollo missions 11 to 17 (except Apollo 13, which aborted its planned lunar landing) removed 380.05 kilograms (837.87 lb) of lunar rock and soil in 2,196 separate samples.
Scientific instrument packages were installed on the lunar surface during all the Apollo landings. Long-lived instrument stations, including heat flow probes, seismometers, and magnetometers, were installed at the Apollo 12, 14, 15, 16, and 17 landing sites. Direct transmission of data to Earth concluded in late 1977 because of budgetary considerations, but as the stations' lunar laser ranging corner-cube retroreflector arrays are passive instruments, they are still being used. Apollo 17 in 1972 remains the last crewed mission to the Moon. Explorer 49 in 1973 was the last dedicated U.S. probe to the Moon until the 1990s.
The Soviet Union continued sending robotic missions to the Moon until 1976, deploying in 1970 with Luna 17 the first remote controlled rover Lunokhod 1 on an extraterrestrial surface, and collecting and returning 0.3 kg of rock and soil samples with three Luna sample return missions (Luna 16 in 1970, Luna 20 in 1972, and Luna 24 in 1976).
Moon Treaty and explorational absence (1976–1990)
A near lunar quietude of fourteen years followed the last Soviet mission to the Moon of 1976. Astronautics had shifted its focus towards the exploration of the inner (e.g. Venera program) and outer (e.g. Pioneer 10, 1972) Solar System planets, but also towards Earth orbit, developing and continuously operating, beside communication satellites, Earth observation satellites (e.g. Landsat program, 1972) space telescopes and particularly space stations (e.g. Salyut program, 1971).
The until 1979 negotiated Moon treaty, with its ratification in 1984 by its few signatories was about the only major activity regarding the Moon until 1990.
Renewed exploration (1990-present)
In 1994, the U.S. dedicated a mission to fly a spacecraft (Clementine) to the Moon again for the first time since 1973. This mission obtained the first near-global topographic map of the Moon, and the first global multispectral images of the lunar surface. In 1998 this was followed by the Lunar Prospector mission, whose instruments indicated the presence of excess hydrogen at the lunar poles, which is likely to have been caused by the presence of water ice in the upper few meters of the regolith within permanently shadowed craters.
The next years saw a row of first missions to the Moon by a new group of states actively exploring the Moon. Between 2004 and 2006 the first spacecraft by the European Space Agency (ESA) (SMART-1) reached the Moon, recording the first detailed survey of chemical elements on the lunar surface. The Chinese Lunar Exploration Program began with Chang'e 1 between 2007 and 2009, obtaining a full image map of the Moon. India reached the Moon in 2008 for the first time with its Chandrayaan-1, creating a high-resolution chemical, mineralogical and photo-geological map of the lunar surface, and confirming the presence of water molecules in lunar soil.
The U.S. launched the Lunar Reconnaissance Orbiter (LRO) and the LCROSS impactor on 18 June 2009. LCROSS completed its mission by making a planned and widely observed impact in the crater Cabeus on 9 October 2009, whereas LRO is currently in operation, obtaining precise lunar altimetry and high-resolution imagery.
China continued its lunar program in 2010 with Chang'e 2, mapping the surface at a higher resolution over an eight-month period, and in 2013 with Chang'e 3, a lunar lander along with a lunar rover named Yutu (Chinese: 玉兔; literally "Jade Rabbit"). This was the first lunar rover mission since Lunokhod 2 in 1973 and the first lunar soft landing since Luna 24 in 1976.
In 2014 the first privately funded probe, the Manfred Memorial Moon Mission, reached the Moon.
Also in 2019, India successfully sent its second probe, Chandrayaan-2 to the Moon.
With the signing of the U.S.-led Artemis Accords in 2020, the Artemis program aims to return in the astronauts to the Moon in the 2020s. The Accords have been joined by a growing number of countries. The introduction of the Artemis Accords has fueled a renewed discussion about the international framework and cooperation of lunar activity, building on the Moon Treaty and the ESA-led Moon Village concept. The U.S. developed plans for returning to the Moon beginning in 2004, which resulted in several programs. The Artemis program has advanced the farthest, and includes plans to send the first woman to the Moon as well as build an international lunar space station called Lunar Gateway.
Upcoming lunar missions include the Artemis program missions and Russia's first lunar mission, Luna-Glob: an uncrewed lander with a set of seismometers, and an orbiter based on its failed Martian Fobos-Grunt mission.
China has announced in 2021 the plan to develop and construct with Russia an International Lunar Research Station towards and into the 2030s. India in 2006 had among others expressed its hope to send people to the Moon by 2020.
Humans have been active around and on the Moon for more than half a century, having send a wide range of missions to the Moon, having stayed robotically and with people, leaving many traces and having set up temporary moonbases. The Moon remains a challenging and particular environment.
While the Moon has the lowest planetary protection target-categorization, its degradation as a pristine body and scientific place has been discussed. If there is astronomy performed from the Moon, it will need to be free from any physical and radio pollution. While the Moon has no significant atmosphere, traffic and impacts on the Moon causes clouds of dust that can spread far and possibly contaminate the original state of the Moon and its special scientific content. Scholar Alice Gorman asserts that, although the Moon is inhospitable, it is not dead, and that sustainable human activity would require treating the Moon's ecology as a co-participant.
The so-called "Tardigrade affair" of the 2019 crashed Beresheet lander and its carrying of tardigrades has been discussed as an example for lacking measures and lacking international regulation for planetary protection.
Space debris beyond Earth around the Moon has been considered as a future challenge with increasing numbers of missions to the Moon, particularly as a danger for such missions. As such lunar waste management has been raised as an issue which future lunar missions, particularly on the surface, need to tackle.
Beside the remains of human activity on the Moon, there have been some intended permanent installations like the Moon Museum art piece, Apollo 11 goodwill messages, six lunar plaques, the Fallen Astronaut memorial, and other artifacts.
Longterm missions continuing to be active are some orbiters such as the 2009-launched Lunar Reconnaissance Orbiter surveilling the Moon for future missions, as well as some Landers such as the 2013-launched Chang'e 3 with its Lunar Ultraviolet Telescope still operational. Five retroreflectors have been installed on the Moon since the 1970s and since used for accurate measurements of the physical librations through laser ranging to the Moon.
There are several missions by different agencies and companies planned to establish a longterm human presence on the Moon, with the Lunar Gateway as the currently most advanced project as part of the Artemis program.
Astronomy from the Moon
For many years, the Moon has been recognized as an excellent site for telescopes. It is relatively nearby; astronomical seeing is not a concern; certain craters near the poles are permanently dark and cold, and thus especially useful for infrared telescopes; and radio telescopes on the far side would be shielded from the radio chatter of Earth. The lunar soil, although it poses a problem for any moving parts of telescopes, can be mixed with carbon nanotubes and epoxies and employed in the construction of mirrors up to 50 meters in diameter. A lunar zenith telescope can be made cheaply with an ionic liquid.
Living on the Moon
The only instances of humans living on the Moon have taken place in an Apollo Lunar Module for several days at a time (for example, during the Apollo 17 mission). One challenge to astronauts during their stay on the surface is that lunar dust sticks to their suits and is carried into their quarters. Astronauts could taste and smell the dust, calling it the "Apollo aroma". This fine lunar dust can cause health issues.
Although Luna landers scattered pennants of the Soviet Union on the Moon, and U.S. flags were symbolically planted at their landing sites by the Apollo astronauts, no nation claims ownership of any part of the Moon's surface. Likewise no private ownership of parts of the Moon, or as a whole, is considered credible.
The 1967 Outer Space Treaty defines the Moon and all outer space as the "province of all mankind". It restricts the use of the Moon to peaceful purposes, explicitly banning military installations and weapons of mass destruction. A majority of countries are parties of this treaty. The 1979 Moon Agreement was created to elaborate, and restrict the exploitation of the Moon's resources by any single nation, leaving it to a yet unspecified international regulatory regime. As of January 2020, it has been signed and ratified by 18 nations, none of which have human spaceflight capabilities.
Since 2020 countries have joined the U.S. in their Artemis Accords, which are challenging the treaty. The U.S. has furthermore emphasized in an presidential executive order ("Encouraging International Support for the Recovery and Use of Space Resources.") that "the United States does not view outer space as a 'global commons'" and calls the Moon Agreement "a failed attempt at constraining free enterprise."
With Australia signing and ratifying both the Moon Treaty in 1986 as well as the Artemis Accords in 2020, there has been a discussion if they can be harmonized. In this light an Implementation Agreement for the Moon Treaty has been advocated for, as a way to compensate for the shortcomings of the Moon Treaty and to harmonize it with other laws, allowing it to be more widely accepted.
In the face of such increasing commercial and national interest, particularly prospecting territories, U.S. lawmakers have introduced in late 2020 specific regulation for the conservation of historic landing sites and interest groups have argued for making such sites World Heritage Sites and zones of scientific value protected zones, all of which add to the legal availability and territorialization of the Moon.
In 2021 the Declaration of the Rights of the Moon was created by a group of "lawyers, space archaeologists and concerned citizens", drawing on precedents in the Rights of Nature movement and the concept of legal personality for non-human entities in space.
In light of future development on the Moon some international and multi-space agency organizations have been created:
- International Lunar Exploration Working Group (ILEWG)
- Moon Village Association (MVA)
- International Space Exploration Coordination Group (ISECG)
In culture and life
Since pre-historic times people have taken note of the Moon's phases, its waxing and waning, and used it to keep record of time. Tally sticks, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon. The counting of the days between the Moon's phases gave eventually rise to generalized time periods of the full lunar cycle as months, and possibly of its phases as weeks.
The words for the month in a range of different languages carry this relation between the period of the month and the Moon etymologically. The English month as well as moon, and its cognates in other Indo-European languages (e.g. the Latin mensis and Ancient Greek μείς (meis) or μήν (mēn), meaning "month") stem from the Proto-Indo-European (PIE) root of moon, *méh1nōt, derived from the PIE verbal root *meh1-, "to measure", "indicat[ing] a functional conception of the Moon, i.e. marker of the month" (cf. the English words measure and menstrual). To give another example from a different language family, the Chinese language uses the same word (月) for moon as well as for month, which furthermore can be found in the symbols for the word week (星期).
This lunar timekeeping gave rise to the historically dominant, but varied, lunisolar calendars. The 7th-century Islamic calendar is an example of a purely lunar calendar, where months are traditionally determined by the visual sighting of the hilal, or earliest crescent moon, over the horizon.
Of particular significance has been the occasion of full moon, highlighted and celebrated in a range of calenders and cultures. Around autumnal equinox, the Full Moon is called the Harvest Moon and is celebrated with festivities such as the Harvest Moon Festival of the Chinese Lunar Calendar, its second most important celebration after Chinese New Year.
Furthermore, association of time with the Moon can also be found in religion, such as the ancient Egyptian temporal and lunar deity Khonsu.
For the representation of the Moon, especially its lunar phases, the crescent symbol (🌙) has been particularly used by many cultures. In writing systems such as Chinese the crescent has developed into the symbol 月, the word for Moon, and in ancient Egyptian it was the symbol 𓇹, which is spelled like the ancient Egyptian lunar deity Iah, meaning Moon.
Iconographically the crescent was used in Mesopotamia as the primary symbol of Nanna/Sîn, the ancient Sumerian lunar deity, who was the father of Innana/Ishtar, the goddess of the planet Venus (symbolized as the eight pointed Star of Ishtar), and Utu/Shamash, the god of the Sun (symbolized as a disc, optionally with eight rays), all three often depicted next to each other. Nanna was later known as Sîn, and was particularly associated with magic and sorcery.
The crescent was further used as an element of lunar deities wearing headgears or crowns in an arrangement reminiscent of horns, as in the case of the ancient Greek Selene or the ancient Egyptian Khonsu. Selene is associated with Artemis and paralleled by the Roman Luna, which both are occasionally depicted driving a chariot, like the Hindu lunar deity Chandra. The different or sharing aspects of deities within pantheons has been observed in many cultures, especially by later or contemporary culture, particularly forming triple deities. The Moon in Roman mythology for example has been associated with Juno and Diana, while Luna being identified as their byname and as part of a triplet (diva triformis) with Diana and Proserpina, Hecate being identified as their binding manifestation as trimorphos.
The star and crescent (☪️) arrangement goes back to the Bronze Age, representing either the Sun and Moon, or the Moon and planet Venus, in combination. It came to represent the goddess Artemis or Hecate, and via the patronage of Hecate came to be used as a symbol of Byzantium, possibly influencing the development of the Ottoman flag, specifically the combination of the Turkish crescent with a star. Since then the heraldric use of the star and crescent proliferated becoming a popular symbol for Islam (as the hilal of the Islamic calendar) and for a range of nations.
In Roman Catholic Marian veneration, the Virgin Mary (Queen of Heaven) has been depicted since the late middle ages on a crescent and adorned with stars. In Islam Muhammad is particularly attributed with the Moon through the so-called splitting of the Moon (Arabic: انشقاق القمر) miracle.
The contrast between the brighter highlands and the darker maria have been seen by different cultures forming abstract shapes, which are among others the Man in the Moon or the Moon Rabbit (e.g. the Chinese Tu'er Ye or in Indigenous American mythologies, as with the aspect of the Mayan Moon goddess).
Modern culture representation
The perception of the Moon in modern times has been informed by telescope enabled modern astronomy and later by spaceflight enabled actual human activity at the Moon, particularly the culturally impactful lunar landings. These new insights inspired cultural references, connecting romantic reflections about the Moon and speculative fiction such as science-fiction dealing with the Moon.
Contemporarily the Moon has been seen as a place for economic expansion into space, with missions prospecting for lunar resources. This has been accompanied with renewed public and critical reflection on humanity's cultural and legal relation to the celestial body, especially regarding colonialism, as in the 1970 poem "Whitey on the Moon". In this light the Moon's nature has been invoked, particularly for lunar conservation and as a common.
The lunar effect is a purported unproven correlation between specific stages of the roughly 29.5-day lunar cycle and behavior and physiological changes in living beings on Earth, including humans. The Moon has long been associated with insanity and irrationality; the words lunacy and lunatic are derived from the Latin name for the Moon, Luna. Philosophers Aristotle and Pliny the Elder argued that the full moon induced insanity in susceptible individuals, believing that the brain, which is mostly water, must be affected by the Moon and its power over the tides, but the Moon's gravity is too slight to affect any single person. Even today, people who believe in a lunar effect claim that admissions to psychiatric hospitals, traffic accidents, homicides or suicides increase during a full moon, but dozens of studies invalidate these claims.
- Between 18.29° and 28.58° to Earth's equator.
- There are a number of near-Earth asteroids, including 3753 Cruithne, that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term (Morais et al, 2002). These are quasi-satellites – they are not moons as they do not orbit Earth. For more information, see Other moons of Earth.
- The maximum value is given based on scaling of the brightness from the value of −12.74 given for an equator to Moon-centre distance of 378 000 km in the NASA factsheet reference to the minimum Earth–Moon distance given there, after the latter is corrected for Earth's equatorial radius of 6 378 km, giving 350 600 km. The minimum value (for a distant new moon) is based on a similar scaling using the maximum Earth–Moon distance of 407 000 km (given in the factsheet) and by calculating the brightness of the earthshine onto such a new moon. The brightness of the earthshine is [ Earth albedo × (Earth radius / Radius of Moon's orbit)2 ] relative to the direct solar illumination that occurs for a full moon. (Earth albedo = 0.367; Earth radius = (polar radius × equatorial radius)½ = 6 367 km.)
- The range of angular size values given are based on simple scaling of the following values given in the fact sheet reference: at an Earth-equator to Moon-centre distance of 378 000 km, the angular size is 1896 arcseconds. The same fact sheet gives extreme Earth–Moon distances of 407 000 km and 357 000 km. For the maximum angular size, the minimum distance has to be corrected for Earth's equatorial radius of 6 378 km, giving 350 600 km.
- Lucey et al. (2006) give 107 particles cm−3 by day and 105 particles cm−3 by night. Along with equatorial surface temperatures of 390 K by day and 100 K by night, the ideal gas law yields the pressures given in the infobox (rounded to the nearest order of magnitude): 10−7 Pa by day and 10−10 Pa by night.
- With 27% the diameter and 60% the density of Earth, the Moon has 1.23% of the mass of Earth. The moon Charon is larger relative to its primary Pluto, but Earth and the Moon are different since Pluto is considered a dwarf planet and not a planet, unlike Earth.
- There is no strong correlation between the sizes of planets and the sizes of their satellites. Larger planets tend to have more satellites, both large and small, than smaller planets.
- More accurately, the Moon's mean sidereal period (fixed star to fixed star) is 27.321661 days (27 d 07 h 43 min 11.5 s), and its mean tropical orbital period (from equinox to equinox) is 27.321582 days (27 d 07 h 43 min 04.7 s) (Explanatory Supplement to the Astronomical Ephemeris, 1961, at p.107).
- More accurately, the Moon's mean synodic period (between mean solar conjunctions) is 29.530589 days (29 d 12 h 44 min 02.9 s) (Explanatory Supplement to the Astronomical Ephemeris, 1961, at p.107).
- The Sun's apparent magnitude is −26.7, while the full moon's apparent magnitude is −12.7.
- See graph in Sun#Life phases. At present, the diameter of the Sun is increasing at a rate of about five percent per billion years. This is very similar to the rate at which the apparent angular diameter of the Moon is decreasing as it recedes from Earth.
- On average, the Moon covers an area of 0.21078 square degrees on the night sky.
- Wieczorek, Mark A.; Jolliff, Bradley L.; Khan, Amir; Pritchard, Matthew E.; Weiss, Benjamin P.; Williams, James G.; Hood, Lon L.; Righter, Kevin; Neal, Clive R.; Shearer, Charles K.; McCallum, I. Stewart; Tompkins, Stephanie; Hawke, B. Ray; Peterson, Chris; Gillis, Jeffrey J.; Bussey, Ben (2006). "The constitution and structure of the lunar interior". Reviews in Mineralogy and Geochemistry. 60 (1): 221–364. Bibcode:2006RvMG...60..221W. doi:10.2138/rmg.2006.60.3. S2CID 130734866. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Lang, Kenneth R. (2011). The Cambridge Guide to the Solar System (2nd ed.). Cambridge University Press. ISBN 9781139494175. Archived from the original on 1 January 2016.
- Morais, M. H. M.; Morbidelli, A. (2002). "The Population of Near-Earth Asteroids in Coorbital Motion with the Earth". Icarus. 160 (1): 1–9. Bibcode:2002Icar..160....1M. doi:10.1006/icar.2002.6937. hdl:10316/4391. S2CID 55214551. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Williams, David R. (2 February 2006). "Moon Fact Sheet". NASA/National Space Science Data Center. Archived from the original on 23 March 2010. Retrieved 31 December 2008.
- Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Lemoine, Frank G. (1 January 1997). "Topography of the Moon from the Clementine lidar". Journal of Geophysical Research. 102 (E1): 1601. Bibcode:1997JGR...102.1591S. doi:10.1029/96JE02940. hdl:2060/19980018849. S2CID 17475023. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Terry, Paul (2013). Top 10 of Everything. Octopus Publishing Group Ltd. p. 226. ISBN 978-0-600-62887-3.
- Williams, James G.; Newhall, XX; Dickey, Jean O. (1996). "Lunar moments, tides, orientation, and coordinate frames". Planetary and Space Science. 44 (10): 1077–1080. Bibcode:1996P&SS...44.1077W. doi:10.1016/0032-0633(95)00154-9.
- Hamilton, Calvin J.; Hamilton, Rosanna L., The Moon, Views of the Solar System Archived 4 February 2016 at the Wayback Machine, 1995–2011.
- Makemson, Maud W. (1971). "Determination of selenographic positions". The Moon. 2 (3): 293–308. Bibcode:1971Moon....2..293M. doi:10.1007/BF00561882. S2CID 119603394.
- Archinal, Brent A.; A'Hearn, Michael F.; Bowell, Edward G.; Conrad, Albert R.; Consolmagno, Guy J.; Courtin, Régis; Fukushima, Toshio; Hestroffer, Daniel; Hilton, James L.; Krasinsky, George A.; Neumann, Gregory A.; Oberst, Jürgen; Seidelmann, P. Kenneth; Stooke, Philip J.; Tholen, David J.; Thomas, Paul C.; Williams, Iwan P. (2010). "Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2009" (PDF). Celestial Mechanics and Dynamical Astronomy. 109 (2): 101–135. Bibcode:2011CeMDA.109..101A. doi:10.1007/s10569-010-9320-4. S2CID 189842666. Archived from the original (PDF) on 4 March 2016. Retrieved 24 September 2018. also available "via usgs.gov" (PDF). Archived (PDF) from the original on 27 April 2019. Retrieved 26 September 2018.
- Matthews, Grant (2008). "Celestial body irradiance determination from an underfilled satellite radiometer: application to albedo and thermal emission measurements of the Moon using CERES". Applied Optics. 47 (27): 4981–4993. Bibcode:2008ApOpt..47.4981M. doi:10.1364/AO.47.004981. PMID 18806861.
- Bugby, D. C.; Farmer, J. T.; O’Connor, B. F.; Wirzburger, M. J.; C. J. Stouffer, E. D. Abel (January 2010). Two‐Phase Thermal Switching System for a Small, Extended Duration Lunar Surface Science Platform. AIP Conference Proceedings. Vol. 1208. pp. 76–83. Bibcode:2010AIPC.1208...76B. doi:10.1063/1.3326291. hdl:2060/20100009810.
- Vasavada, A. R.; Paige, D. A.; Wood, S. E. (1999). "Near-Surface Temperatures on Mercury and the Moon and the Stability of Polar Ice Deposits". Icarus. 141 (2): 179–193. Bibcode:1999Icar..141..179V. doi:10.1006/icar.1999.6175. S2CID 37706412. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Zhang S, Wimmer-Schweingruber RF, Yu J, Wang C, Fu Q, Zou Y, et al. (2020). "First measurements of the radiation dose on the lunar surface". Science Advances. 6 (39). Bibcode:2020SciA....6.1334Z. doi:10.1126/sciadv.aaz1334. PMC 7518862. PMID 32978156.
We measured an average total absorbed dose rate in silicon of 13.2 ± 1 μGy/hour ... LND measured an average dose equivalent of 1369 μSv/day on the surface of the Moon
- Lucey, Paul; Korotev, Randy L.; Gillis, Jeffrey J.; Taylor, Larry A.; Lawrence, David; Campbell, Bruce A.; Elphic, Rick; Feldman, Bill; Hood, Lon L.; Hunten, Donald; Mendillo, Michael; Noble, Sarah; Papike, James J.; Reedy, Robert C.; Lawson, Stefanie; Prettyman, Tom; Gasnault, Olivier; Maurice, Sylvestre (2006). "Understanding the lunar surface and space-Moon interactions". Reviews in Mineralogy and Geochemistry. 60 (1): 83–219. Bibcode:2006RvMG...60...83L. doi:10.2138/rmg.2006.60.2.
- Horner, Jonti (18 July 2019). "How big is the Moon?". Archived from the original on 7 November 2020. Retrieved 15 November 2020.
- Metzger, Philip; Grundy, Will; Sykes, Mark; Stern, Alan; Bell, James; Detelich, Charlene; Runyon, Kirby; Summers, Michael (2021), "Moons are planets: Scientific usefulness versus cultural teleology in the taxonomy of planetary science", Icarus, 374: 114768, doi:10.1016/j.icarus.2021.114768, S2CID 240071005
- "Naming Astronomical Objects: Spelling of Names". International Astronomical Union. Archived from the original on 16 December 2008. Retrieved 6 April 2020.
- "Gazetteer of Planetary Nomenclature: Planetary Nomenclature FAQ". USGS Astrogeology Research Program. Archived from the original on 27 May 2010. Retrieved 6 April 2020.
- Orel, Vladimir (2003). A Handbook of Germanic Etymology. Brill. Archived from the original on 17 June 2020. Retrieved 5 March 2020.
- López-Menchero, Fernando (22 May 2020). "Late Proto-Indo-European Etymological Lexicon". Archived from the original on 22 May 2020. Retrieved 30 July 2022.
- Barnhart, Robert K. (1995). The Barnhart Concise Dictionary of Etymology. HarperCollins. p. 487. ISBN 978-0-06-270084-1.
- E.g.: Hall III, James A. (2016). Moons of the Solar System. Springer International. ISBN 978-3-319-20636-3.
- "Luna". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- "Cynthia". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- "selenian". Merriam-Webster Dictionary.
- "selenian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- "selenic". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- "selenic". Merriam-Webster Dictionary.
- "Oxford English Dictionary: lunar, a. and n." Oxford English Dictionary: Second Edition 1989. Oxford University Press. Archived from the original on 19 August 2020. Retrieved 23 March 2010.
- σελήνη. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
- Pannen, Imke (2010). When the Bad Bleeds: Mantic Elements in English Renaissance Revenge Tragedy. V&R unipress GmbH. pp. 96–. ISBN 978-3-89971-640-5. Archived from the original on 4 September 2016.
- Thiemens, Maxwell M.; Sprung, Peter; Fonseca, Raúl O. C.; Leitzke, Felipe P.; Münker, Carsten (July 2019). "Early Moon formation inferred from hafnium-tungsten systematics". Nature Geoscience. 12 (9): 696–700. Bibcode:2019NatGe..12..696T. doi:10.1038/s41561-019-0398-3. S2CID 198997377.
- "The Moon is older than scientists thought". Universe Today. Archived from the original on 3 August 2019. Retrieved 3 August 2019.
- Barboni, M.; Boehnke, P.; Keller, C.B.; Kohl, I.E.; Schoene, B.; Young, E.D.; McKeegan, K.D. (2017). "Early formation of the Moon 4.51 billion years ago". Science Advances. 3 (1): e1602365. Bibcode:2017SciA....3E2365B. doi:10.1126/sciadv.1602365. PMC 5226643. PMID 28097222.
- Binder, A. B. (1974). "On the origin of the Moon by rotational fission". The Moon. 11 (2): 53–76. Bibcode:1974Moon...11...53B. doi:10.1007/BF01877794. S2CID 122622374.
- Stroud, Rick (2009). The Book of the Moon. Walken and Company. pp. 24–27. ISBN 978-0-8027-1734-4. Archived from the original on 17 June 2020. Retrieved 11 November 2019.
- Mitler, H. E. (1975). "Formation of an iron-poor moon by partial capture, or: Yet another exotic theory of lunar origin". Icarus. 24 (2): 256–268. Bibcode:1975Icar...24..256M. doi:10.1016/0019-1035(75)90102-5.
- Stevenson, D.J. (1987). "Origin of the moon–The collision hypothesis". Annual Review of Earth and Planetary Sciences. 15 (1): 271–315. Bibcode:1987AREPS..15..271S. doi:10.1146/annurev.ea.15.050187.001415. S2CID 53516498. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Taylor, G. Jeffrey (31 December 1998). "Origin of the Earth and Moon". Planetary Science Research Discoveries. Hawai'i Institute of Geophysics and Planetology. Archived from the original on 10 June 2010. Retrieved 7 April 2010.
- "Asteroids Bear Scars of Moon's Violent Formation". 16 April 2015. Archived from the original on 8 October 2016.
- van Putten, Maurice H. P. M. (July 2017). "Scaling in global tidal dissipation of the Earth-Moon system". New Astronomy. 54: 115–121. arXiv:1609.07474. Bibcode:2017NewA...54..115V. doi:10.1016/j.newast.2017.01.012. S2CID 119285032.
- Canup, R.; Asphaug, E. (2001). "Origin of the Moon in a giant impact near the end of Earth's formation". Nature. 412 (6848): 708–712. Bibcode:2001Natur.412..708C. doi:10.1038/35089010. PMID 11507633. S2CID 4413525.
- "Earth-Asteroid Collision Formed Moon Later Than Thought". National Geographic. 28 October 2010. Archived from the original on 18 April 2009. Retrieved 7 May 2012.
- Kleine, Thorsten (2008). "2008 Pellas-Ryder Award for Mathieu Touboul" (PDF). Meteoritics and Planetary Science. 43 (S7): A11–A12. Bibcode:2008M&PS...43...11K. doi:10.1111/j.1945-5100.2008.tb00709.x. S2CID 128609987. Archived from the original (PDF) on 27 July 2018. Retrieved 8 April 2020.
- Touboul, M.; Kleine, T.; Bourdon, B.; Palme, H.; Wieler, R. (2007). "Late formation and prolonged differentiation of the Moon inferred from W isotopes in lunar metals". Nature. 450 (7173): 1206–1209. Bibcode:2007Natur.450.1206T. doi:10.1038/nature06428. PMID 18097403. S2CID 4416259.
- "Flying Oceans of Magma Help Demystify the Moon's Creation". National Geographic. 8 April 2015. Archived from the original on 9 April 2015.
- Pahlevan, Kaveh; Stevenson, David J. (2007). "Equilibration in the aftermath of the lunar-forming giant impact". Earth and Planetary Science Letters. 262 (3–4): 438–449. arXiv:1012.5323. Bibcode:2007E&PSL.262..438P. doi:10.1016/j.epsl.2007.07.055. S2CID 53064179.
- Nield, Ted (2009). "Moonwalk (summary of meeting at Meteoritical Society's 72nd Annual Meeting, Nancy, France)". Geoscientist. Vol. 19. p. 8. Archived from the original on 27 September 2012.
- Warren, P. H. (1985). "The magma ocean concept and lunar evolution". Annual Review of Earth and Planetary Sciences. 13 (1): 201–240. Bibcode:1985AREPS..13..201W. doi:10.1146/annurev.ea.13.050185.001221.
- Tonks, W. Brian; Melosh, H. Jay (1993). "Magma ocean formation due to giant impacts". Journal of Geophysical Research. 98 (E3): 5319–5333. Bibcode:1993JGR....98.5319T. doi:10.1029/92JE02726.
- Daniel Clery (11 October 2013). "Impact Theory Gets Whacked". Science. 342 (6155): 183–185. Bibcode:2013Sci...342..183C. doi:10.1126/science.342.6155.183. PMID 24115419.
- Kegerreis, J.A.; et al. (4 October 2022). "Immediate Origin of the Moon as a Post-impact Satellite". The Astrophysical Journal Letters. 937 (L40): L40. arXiv:2210.01814. Bibcode:2022ApJ...937L..40K. doi:10.3847/2041-8213/ac8d96. S2CID 249267497. Retrieved 8 October 2022.
- "Earth-Moon Dynamics". Lunar and Planetary Institute. Retrieved 2 September 2022.
- Hiesinger, H.; Head, J. W.; Wolf, U.; Jaumann, R.; Neukum, G. (2003). "Ages and stratigraphy of mare basalts in Oceanus Procellarum, Mare Numbium, Mare Cognitum, and Mare Insularum". Journal of Geophysical Research. 108 (E7): 1029. Bibcode:2003JGRE..108.5065H. doi:10.1029/2002JE001985. S2CID 9570915.
- Papike, J.; Ryder, G.; Shearer, C. (1998). "Lunar Samples". Reviews in Mineralogy and Geochemistry. 36: 5.1–5.234.
- "Lunar Far Side Highlands". ESA Science & Technology. 14 July 2006. Retrieved 2 September 2022.
- Garrick-Bethell, Ian; Perera, Viranga; Nimmo, Francis; Zuber, Maria T. (2014). "The tidal-rotational shape of the Moon and evidence for polar wander" (PDF). Nature. 512 (7513): 181–184. Bibcode:2014Natur.512..181G. doi:10.1038/nature13639. PMID 25079322. S2CID 4452886. Archived (PDF) from the original on 4 August 2020. Retrieved 12 April 2020.
- "Space Topics: Pluto and Charon". The Planetary Society. Archived from the original on 18 February 2012. Retrieved 6 April 2010.
- Spudis, P. D. (2004). "Moon". World Book Online Reference Center, NASA. Archived from the original on 3 July 2013. Retrieved 12 April 2007.
- Runcorn, Stanley Keith (31 March 1977). "Interpretation of lunar potential fields". Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences. 285 (1327): 507–516. Bibcode:1977RSPTA.285..507R. doi:10.1098/rsta.1977.0094. S2CID 124703189.
- Brown, D.; Anderson, J. (6 January 2011). "NASA Research Team Reveals Moon Has Earth-Like Core". NASA. NASA. Archived from the original on 11 January 2012.
- Weber, R.C.; Lin, P.-Y.; Garnero, E.J.; Williams, Q.; Lognonne, P. (21 January 2011). "Seismic Detection of the Lunar Core" (PDF). Science. 331 (6015): 309–312. Bibcode:2011Sci...331..309W. doi:10.1126/science.1199375. PMID 21212323. S2CID 206530647. Archived from the original (PDF) on 15 October 2015. Retrieved 10 April 2017.
- Nemchin, A.; Timms, N.; Pidgeon, R.; Geisler, T.; Reddy, S.; Meyer, C. (2009). "Timing of crystallization of the lunar magma ocean constrained by the oldest zircon". Nature Geoscience. 2 (2): 133–136. Bibcode:2009NatGe...2..133N. doi:10.1038/ngeo417. hdl:20.500.11937/44375.
- Shearer, Charles K.; Hess, Paul C.; Wieczorek, Mark A.; Pritchard, Matt E.; Parmentier, E. Mark; Borg, Lars E.; Longhi, John; Elkins-Tanton, Linda T.; Neal, Clive R.; Antonenko, Irene; Canup, Robin M.; Halliday, Alex N.; Grove, Tim L.; Hager, Bradford H.; Lee, D.-C.; Wiechert, Uwe (2006). "Thermal and magmatic evolution of the Moon". Reviews in Mineralogy and Geochemistry. 60 (1): 365–518. Bibcode:2006RvMG...60..365S. doi:10.2138/rmg.2006.60.4. S2CID 129184748. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Schubert, J. (2004). "Interior composition, structure, and dynamics of the Galilean satellites.". In F. Bagenal; et al. (eds.). Jupiter: The Planet, Satellites, and Magnetosphere. Cambridge University Press. pp. 281–306. ISBN 978-0-521-81808-7.
- Williams, J.G.; Turyshev, S.G.; Boggs, D.H.; Ratcliff, J.T. (2006). "Lunar laser ranging science: Gravitational physics and lunar interior and geodesy". Advances in Space Research. 37 (1): 67–71. arXiv:gr-qc/0412049. Bibcode:2006AdSpR..37...67W. doi:10.1016/j.asr.2005.05.013. S2CID 14801321.
- Evans, Alexander J.; Tikoo, Sonia M.; Jeffrey C., Andrews-Hanna (January 2018). "The Case Against an Early Lunar Dynamo Powered by Core Convection". Geophysical Research Letters. 45 (1): 98–107. Bibcode:2018GeoRL..45...98E. doi:10.1002/2017GL075441.
- Mighani, S.; Wang, H.; Shuster, D.L.; Borlina, C.S.; Nichols, C.I.O.; Weiss, B.P. (2020). "The end of the lunar dynamo". Science Advances. 6 (1): eaax0883. Bibcode:2020SciA....6..883M. doi:10.1126/sciadv.aax0883. PMC 6938704. PMID 31911941.
- Garrick-Bethell, Ian; Weiss, iBenjamin P.; Shuster, David L.; Buz, Jennifer (2009). "Early Lunar Magnetism". Science. 323 (5912): 356–359. Bibcode:2009Sci...323..356G. doi:10.1126/science.1166804. PMID 19150839. S2CID 23227936. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- "Magnetometer / Electron Reflectometer Results". Lunar Prospector (NASA). 2001. Archived from the original on 27 May 2010. Retrieved 17 March 2010.
- Hood, L.L.; Huang, Z. (1991). "Formation of magnetic anomalies antipodal to lunar impact basins: Two-dimensional model calculations". Journal of Geophysical Research. 96 (B6): 9837–9846. Bibcode:1991JGR....96.9837H. doi:10.1029/91JB00308.
- Muller, P.; Sjogren, W. (1968). "Mascons: lunar mass concentrations". Science. 161 (3842): 680–684. Bibcode:1968Sci...161..680M. doi:10.1126/science.161.3842.680. PMID 17801458. S2CID 40110502.
- Richard A. Kerr (12 April 2013). "The Mystery of Our Moon's Gravitational Bumps Solved?". Science. 340 (6129): 138–139. doi:10.1126/science.340.6129.138-a. PMID 23580504.
- Konopliv, A.; Asmar, S.; Carranza, E.; Sjogren, W.; Yuan, D. (2001). "Recent gravity models as a result of the Lunar Prospector mission" (PDF). Icarus. 50 (1): 1–18. Bibcode:2001Icar..150....1K. CiteSeerX 10.1.1.18.1930. doi:10.1006/icar.2000.6573. Archived from the original (PDF) on 13 November 2004.
- "Radioactive Moon". Science Mission Directorate. 8 September 2005. Archived from the original on 2 November 2019. Retrieved 28 July 2022.
- "We Finally Know How Much Radiation There Is on The Moon, And It's Not Great News". ScienceAlert. 26 September 2020. Archived from the original on 28 July 2022. Retrieved 28 July 2022.
- Wall, Mike (28 September 2020). "We now know exactly how much radiation astronauts will face on the moon". Space.com. Retrieved 7 August 2022.
- Wall, Mike (9 December 2013). "Radiation on Mars 'Manageable' for Manned Mission, Curiosity Rover Reveals". Space.com. Retrieved 7 August 2022.
- Rambaux, N.; Williams, J. G. (2011). "The Moon's physical librations and determination of their free modes". Celestial Mechanics and Dynamical Astronomy. 109 (1): 85–100. Bibcode:2011CeMDA.109...85R. doi:10.1007/s10569-010-9314-2. S2CID 45209988. Archived from the original on 30 July 2022. Retrieved 30 July 2022.
- Rocheleau, Jake (21 May 2012). "Temperature on the Moon – Surface Temperature of the Moon". PlanetFacts.org. Archived from the original on 27 May 2015.
- Amos, Jonathan (16 December 2009). "'Coldest place' found on the Moon". BBC News. Archived from the original on 11 August 2017. Retrieved 20 March 2010.
- Martel, L. M. V. (4 June 2003). "The Moon's Dark, Icy Poles". Planetary Science Research Discoveries: 73. Bibcode:2003psrd.reptE..73M. Archived from the original on 1 March 2012. Retrieved 12 April 2007.
- "Diviner News". UCLA. 17 September 2009. Archived from the original on 7 March 2010. Retrieved 17 March 2010.
- Schuerger, Andrew C.; Moores, John E.; Smith, David J.; Reitz, Günther (June 2019). "A Lunar Microbial Survival Model for Predicting the Forward Contamination of the Moon". Astrobiology. 19 (6): 730–756. Bibcode:2019AsBio..19..730S. doi:10.1089/ast.2018.1952. PMID 30810338. S2CID 73491587.
- "Lunar horizon glow from Surveyor 7". The Planetary Society. 6 May 2016. Retrieved 8 August 2022.
- "NASA Mission To Study Mysterious Lunar Twilight Rays". Science Mission Directorate. 3 September 2013. Retrieved 8 August 2022.
- Colwell, Joshua E.; Robertson, Scott R.; Horányi, Mihály; Wang, Xu; Poppe, Andrew; Wheeler, Patrick (1 January 2009). "Lunar Dust Levitation - Journal of Aerospace Engineering - Vol 22, No 1". Journal of Aerospace Engineering. 22 (1): 2–9. doi:10.1061/(ASCE)0893-1321(2009)22:1(2). Retrieved 8 August 2022.
- Deborah Byrd (24 April 2014). "The zodiacal light, seen from the moon". EarthSky. Retrieved 8 August 2022.
- Globus, Ruth (1977). "Chapter 5, Appendix J: Impact Upon Lunar Atmosphere". In Richard D. Johnson & Charles Holbrow (ed.). Space Settlements: A Design Study. NASA. Archived from the original on 31 May 2010. Retrieved 17 March 2010.
- Crotts, Arlin P.S. (2008). "Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data" (PDF). The Astrophysical Journal. 687 (1): 692–705. arXiv:0706.3949. Bibcode:2008ApJ...687..692C. doi:10.1086/591634. S2CID 16821394. Archived from the original (PDF) on 20 February 2009. Retrieved 29 September 2009.
- Steigerwald, William (17 August 2015). "NASA's LADEE Spacecraft Finds Neon in Lunar Atmosphere". NASA. Archived from the original on 19 August 2015. Retrieved 18 August 2015.
- Stern, S.A. (1999). "The Lunar atmosphere: History, status, current problems, and context". Reviews of Geophysics. 37 (4): 453–491. Bibcode:1999RvGeo..37..453S. CiteSeerX 10.1.1.21.9994. doi:10.1029/1999RG900005. S2CID 10406165.
- Lawson, S.; Feldman, W.; Lawrence, D.; Moore, K.; Elphic, R.; Belian, R. (2005). "Recent outgassing from the lunar surface: the Lunar Prospector alpha particle spectrometer". Journal of Geophysical Research. 110 (E9): 1029. Bibcode:2005JGRE..11009009L. doi:10.1029/2005JE002433.
- R. Sridharan; S.M. Ahmed; Tirtha Pratim Dasa; P. Sreelathaa; P. Pradeepkumara; Neha Naika; Gogulapati Supriya (2010). "'Direct' evidence for water (H2O) in the sunlit lunar ambience from CHACE on MIP of Chandrayaan I". Planetary and Space Science. 58 (6): 947–950. Bibcode:2010P&SS...58..947S. doi:10.1016/j.pss.2010.02.013.
- "NASA: The Moon Once Had an Atmosphere That Faded Away". Time. Archived from the original on 14 October 2017. Retrieved 14 October 2017.
- Drake, Nadia (17 June 2015). "Lopsided Cloud of Dust Discovered Around the Moon". National Geographic News. Archived from the original on 19 June 2015. Retrieved 20 June 2015.
- Horányi, M.; Szalay, J.R.; Kempf, S.; Schmidt, J.; Grün, E.; Srama, R.; Sternovsky, Z. (18 June 2015). "A permanent, asymmetric dust cloud around the Moon". Nature. 522 (7556): 324–326. Bibcode:2015Natur.522..324H. doi:10.1038/nature14479. PMID 26085272. S2CID 4453018.
- Spudis, Paul D.; Cook, A.; Robinson, M.; Bussey, B.; Fessler, B. (January 1998). "Topography of the South Polar Region from Clementine Stereo Imaging". Workshop on New Views of the Moon: Integrated Remotely Sensed, Geophysical, and Sample Datasets: 69. Bibcode:1998nvmi.conf...69S.
- Spudis, Paul D.; Reisse, Robert A.; Gillis, Jeffrey J. (1994). "Ancient Multiring Basins on the Moon Revealed by Clementine Laser Altimetry". Science. 266 (5192): 1848–1851. Bibcode:1994Sci...266.1848S. doi:10.1126/science.266.5192.1848. PMID 17737079. S2CID 41861312.
- Pieters, C. M.; Tompkins, S.; Head, J. W.; Hess, P. C. (1997). "Mineralogy of the Mafic Anomaly in the South Pole‐Aitken Basin: Implications for excavation of the lunar mantle". Geophysical Research Letters. 24 (15): 1903–1906. Bibcode:1997GeoRL..24.1903P. doi:10.1029/97GL01718. hdl:2060/19980018038. S2CID 128767066.
- Taylor, G. J. (17 July 1998). "The Biggest Hole in the Solar System". Planetary Science Research Discoveries: 20. Bibcode:1998psrd.reptE..20T. Archived from the original on 20 August 2007. Retrieved 12 April 2007.
- Schultz, P.H. (March 1997). "Forming the south-pole Aitken basin – The extreme games". Conference Paper, 28th Annual Lunar and Planetary Science Conference. 28: 1259. Bibcode:1997LPI....28.1259S.
- "NASA's LRO Reveals 'Incredible Shrinking Moon'". NASA. 19 August 2010. Archived from the original on 21 August 2010.
- Watters, Thomas R.; Weber, Renee C.; Collins, Geoffrey C.; Howley, Ian J.; Schmerr, Nicholas C.; Johnson, Catherine L. (June 2019). "Shallow seismic activity and young thrust faults on the Moon". Nature Geoscience (published 13 May 2019). 12 (6): 411–417. Bibcode:2019NatGe..12..411W. doi:10.1038/s41561-019-0362-2. ISSN 1752-0894. S2CID 182137223.
- Wlasuk, Peter (2000). Observing the Moon. Springer. p. 19. ISBN 978-1-85233-193-1.
- Norman, M. (21 April 2004). "The Oldest Moon Rocks". Planetary Science Research Discoveries. Hawai'i Institute of Geophysics and Planetology. Archived from the original on 18 April 2007. Retrieved 12 April 2007.
- Wilson, Lionel; Head, James W. (2003). "Lunar Gruithuisen and Mairan domes: Rheology and mode of emplacement". Journal of Geophysical Research. 108 (E2): 5012. Bibcode:2003JGRE..108.5012W. CiteSeerX 10.1.1.654.9619. doi:10.1029/2002JE001909. S2CID 14917901. Archived from the original on 12 March 2007. Retrieved 12 April 2007.
- Gillis, J. J.; Spudis, P. D. (1996). "The Composition and Geologic Setting of Lunar Far Side Maria". Lunar and Planetary Science. 27: 413. Bibcode:1996LPI....27..413G.
- Lawrence, D. J.; Feldman, W. C.; Barraclough, B. L.; Binder, A. B.; Elphic, R. C.; Maurice, S.; Thomsen, D. R. (11 August 1998). "Global Elemental Maps of the Moon: The Lunar Prospector Gamma-Ray Spectrometer". Science. 281 (5382): 1484–1489. Bibcode:1998Sci...281.1484L. doi:10.1126/science.281.5382.1484. PMID 9727970.
- Taylor, G. J. (31 August 2000). "A New Moon for the Twenty-First Century". Planetary Science Research Discoveries: 41. Bibcode:2000psrd.reptE..41T. Archived from the original on 1 March 2012. Retrieved 12 April 2007.
- Phil Berardelli (9 November 2006). "Long Live the Moon!". Science. Archived from the original on 18 October 2014. Retrieved 14 October 2014.
- Jason Major (14 October 2014). "Volcanoes Erupted 'Recently' on the Moon". Discovery News. Archived from the original on 16 October 2014.
- "NASA Mission Finds Widespread Evidence of Young Lunar Volcanism". NASA. 12 October 2014. Archived from the original on 3 January 2015.
- Eric Hand (12 October 2014). "Recent volcanic eruptions on the moon". Science. Archived from the original on 14 October 2014.
- Braden, S.E.; Stopar, J.D.; Robinson, M.S.; Lawrence, S.J.; van der Bogert, C.H.; Hiesinger, H. (2014). "Evidence for basaltic volcanism on the Moon within the past 100 million years". Nature Geoscience. 7 (11): 787–791. Bibcode:2014NatGe...7..787B. doi:10.1038/ngeo2252.
- Srivastava, N.; Gupta, R.P. (2013). "Young viscous flows in the Lowell crater of Orientale basin, Moon: Impact melts or volcanic eruptions?". Planetary and Space Science. 87: 37–45. Bibcode:2013P&SS...87...37S. doi:10.1016/j.pss.2013.09.001.
- Gupta, R.P.; Srivastava, N.; Tiwari, R.K. (2014). "Evidences of relatively new volcanic flows on the Moon". Current Science. 107 (3): 454–460. JSTOR 24103498.
- Whitten, Jennifer; Head, James W.; Staid, Matthew; Pieters, Carle M.; Mustard, John; Clark, Roger; Nettles, Jeff; Klima, Rachel L.; Taylor, Larry (2011). "Lunar mare deposits associated with the Orientale impact basin: New insights into mineralogy, history, mode of emplacement, and relation to Orientale Basin evolution from Moon Mineralogy Mapper (M3) data from Chandrayaan-1". Journal of Geophysical Research. 116: E00G09. Bibcode:2011JGRE..116.0G09W. doi:10.1029/2010JE003736. S2CID 7234547.
- Cho, Y.; et al. (2012). "Young mare volcanism in the Orientale region contemporary with the Procellarum KREEP Terrane (PKT) volcanism peak period 2 b.y. ago". Geophysical Research Letters. 39 (11): L11203. Bibcode:2012GeoRL..3911203C. doi:10.1029/2012GL051838. S2CID 134074700.
- Munsell, K. (4 December 2006). "Majestic Mountains". Solar System Exploration. NASA. Archived from the original on 17 September 2008. Retrieved 12 April 2007.
- Richard Lovett (2011). "Early Earth may have had two moons : Nature News". Nature. doi:10.1038/news.2011.456. Archived from the original on 3 November 2012. Retrieved 1 November 2012.
- "Was our two-faced moon in a small collision?". Theconversation.edu.au. Archived from the original on 30 January 2013. Retrieved 1 November 2012.
- Quillen, Alice C.; Martini, Larkin; Nakajima, Miki (September 2019). "Near/far side asymmetry in the tidally heated Moon". Icarus. 329: 182–196. arXiv:1810.10676. Bibcode:2019Icar..329..182Q. doi:10.1016/j.icarus.2019.04.010. PMC 7489467. PMID 32934397.
- Melosh, H. J. (1989). Impact cratering: A geologic process. Oxford University Press. ISBN 978-0-19-504284-9.
- "Moon Facts". SMART-1. European Space Agency. 2010. Archived from the original on 17 March 2012. Retrieved 12 May 2010.
- Wilhelms, Don (1987). "Relative Ages" (PDF). Geologic History of the Moon. U.S. Geological Survey. Archived from the original (PDF) on 11 June 2010. Retrieved 4 April 2010.
- Hartmann, William K.; Quantin, Cathy; Mangold, Nicolas (2007). "Possible long-term decline in impact rates: 2. Lunar impact-melt data regarding impact history". Icarus. 186 (1): 11–23. Bibcode:2007Icar..186...11H. doi:10.1016/j.icarus.2006.09.009.
- Boyle, Rebecca. "The moon has hundreds more craters than we thought". Archived from the original on 13 October 2016.
- Speyerer, Emerson J.; Povilaitis, Reinhold Z.; Robinson, Mark S.; Thomas, Peter C.; Wagner, Robert V. (13 October 2016). "Quantifying crater production and regolith overturn on the Moon with temporal imaging". Nature. 538 (7624): 215–218. Bibcode:2016Natur.538..215S. doi:10.1038/nature19829. PMID 27734864. S2CID 4443574.
- "Earth's Moon Hit by Surprising Number of Meteoroids". NASA. 13 October 2016. Archived from the original on 2 July 2022. Retrieved 21 May 2021.
- Chrbolková, Kateřina; Kohout, Tomáš; Ďurech, Josef (November 2019). "Reflectance spectra of seven lunar swirls examined by statistical methods: A space weathering study". Icarus. 333: 516–527. Bibcode:2019Icar..333..516C. doi:10.1016/j.icarus.2019.05.024.
- "The Smell of Moondust". NASA. 30 January 2006. Archived from the original on 8 March 2010. Retrieved 15 March 2010.
- Heiken, G. (1991). Vaniman, D.; French, B. (eds.). Lunar Sourcebook, a user's guide to the Moon. New York: Cambridge University Press. p. 286. ISBN 978-0-521-33444-0. Archived from the original on 17 June 2020. Retrieved 17 December 2019.
- Rasmussen, K.L.; Warren, P.H. (1985). "Megaregolith thickness, heat flow, and the bulk composition of the Moon". Nature. 313 (5998): 121–124. Bibcode:1985Natur.313..121R. doi:10.1038/313121a0. S2CID 4245137.
- Margot, J. L.; Campbell, D. B.; Jurgens, R. F.; Slade, M. A. (4 June 1999). "Topography of the Lunar Poles from Radar Interferometry: A Survey of Cold Trap Locations" (PDF). Science. 284 (5420): 1658–1660. Bibcode:1999Sci...284.1658M. CiteSeerX 10.1.1.485.312. doi:10.1126/science.284.5420.1658. PMID 10356393. Archived (PDF) from the original on 11 August 2017. Retrieved 25 October 2017.
- Ward, William R. (1 August 1975). "Past Orientation of the Lunar Spin Axis". Science. 189 (4200): 377–379. Bibcode:1975Sci...189..377W. doi:10.1126/science.189.4200.377. PMID 17840827. S2CID 21185695.
- Seedhouse, Erik (2009). Lunar Outpost: The Challenges of Establishing a Human Settlement on the Moon. Springer-Praxis Books in Space Exploration. Germany: Springer Praxis. p. 136. ISBN 978-0-387-09746-6. Archived from the original on 26 November 2020. Retrieved 22 August 2020.
- Coulter, Dauna (18 March 2010). "The Multiplying Mystery of Moonwater". NASA. Archived from the original on 13 December 2012. Retrieved 28 March 2010.
- Spudis, P. (6 November 2006). "Ice on the Moon". The Space Review. Archived from the original on 22 February 2007. Retrieved 12 April 2007.
- Feldman, W. C.; Maurice, S.; Binder, A. B.; Barraclough, B. L.; R.C. Elphic; D.J. Lawrence (1998). "Fluxes of Fast and Epithermal Neutrons from Lunar Prospector: Evidence for Water Ice at the Lunar Poles". Science. 281 (5382): 1496–1500. Bibcode:1998Sci...281.1496F. doi:10.1126/science.281.5382.1496. PMID 9727973. S2CID 9005608.
- Saal, Alberto E.; Hauri, Erik H.; Cascio, Mauro L.; van Orman, James A.; Rutherford, Malcolm C.; Cooper, Reid F. (2008). "Volatile content of lunar volcanic glasses and the presence of water in the Moon's interior". Nature. 454 (7201): 192–195. Bibcode:2008Natur.454..192S. doi:10.1038/nature07047. PMID 18615079. S2CID 4394004.
- Pieters, C. M.; Goswami, J. N.; Clark, R. N.; Annadurai, M.; Boardman, J.; Buratti, B.; Combe, J.-P.; Dyar, M. D.; Green, R.; Head, J. W.; Hibbitts, C.; Hicks, M.; Isaacson, P.; Klima, R.; Kramer, G.; Kumar, S.; Livo, E.; Lundeen, S.; Malaret, E.; McCord, T.; Mustard, J.; Nettles, J.; Petro, N.; Runyon, C.; Staid, M.; Sunshine, J.; Taylor, L.A.; Tompkins, S.; Varanasi, P. (2009). "Character and Spatial Distribution of OH/H2O on the Surface of the Moon Seen by M3 on Chandrayaan-1". Science. 326 (5952): 568–572. Bibcode:2009Sci...326..568P. doi:10.1126/science.1178658. PMID 19779151. S2CID 447133. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Li, Shuai; Lucey, Paul G.; Milliken, Ralph E.; Hayne, Paul O.; Fisher, Elizabeth; Williams, Jean-Pierre; Hurley, Dana M.; Elphic, Richard C. (August 2018). "Direct evidence of surface exposed water ice in the lunar polar regions". Proceedings of the National Academy of Sciences. 115 (36): 8907–8912. Bibcode:2018PNAS..115.8907L. doi:10.1073/pnas.1802345115. PMC 6130389. PMID 30126996.
- Lakdawalla, Emily (13 November 2009). "LCROSS Lunar Impactor Mission: "Yes, We Found Water!"". The Planetary Society. Archived from the original on 22 January 2010. Retrieved 13 April 2010.
- Colaprete, A.; Ennico, K.; Wooden, D.; Shirley, M.; Heldmann, J.; Marshall, W.; Sollitt, L.; Asphaug, E.; Korycansky, D.; Schultz, P.; Hermalyn, B.; Galal, K.; Bart, G.D.; Goldstein, D.; Summy, D. (1–5 March 2010). "Water and More: An Overview of LCROSS Impact Results". 41st Lunar and Planetary Science Conference. 41 (1533): 2335. Bibcode:2010LPI....41.2335C.
- Colaprete, Anthony; Schultz, Peter; Heldmann, Jennifer; Wooden, Diane; Shirley, Mark; Ennico, Kimberly; Hermalyn, Brendan; Marshall, William; Ricco, Antonio; Elphic, Richard C.; Goldstein, David; Summy, Dustin; Bart, Gwendolyn D.; Asphaug, Erik; Korycansky, Don; Landis, David; Sollitt, Luke (22 October 2010). "Detection of Water in the LCROSS Ejecta Plume". Science. 330 (6003): 463–468. Bibcode:2010Sci...330..463C. doi:10.1126/science.1186986. PMID 20966242. S2CID 206525375. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Hauri, Erik; Thomas Weinreich; Albert E. Saal; Malcolm C. Rutherford; James A. Van Orman (26 May 2011). "High Pre-Eruptive Water Contents Preserved in Lunar Melt Inclusions". Science Express. 10 (1126): 213–215. Bibcode:2011Sci...333..213H. doi:10.1126/science.1204626. PMID 21617039. S2CID 44437587. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- Rincon, Paul (21 August 2018). "Water ice 'detected on Moon's surface'". BBC News. Archived from the original on 21 August 2018. Retrieved 21 August 2018.
- David, Leonard. "Beyond the Shadow of a Doubt, Water Ice Exists on the Moon". Scientific American. Archived from the original on 21 August 2018. Retrieved 21 August 2018.
- "Water Ice Confirmed on the Surface of the Moon for the 1st Time!". Space.com. Archived from the original on 21 August 2018. Retrieved 21 August 2018.
- Honniball, C.I.; et al. (26 October 2020). "Molecular water detected on the sunlit Moon by SOFIA". Nature Astronomy. 5 (2): 121–127. Bibcode:2021NatAs...5..121H. doi:10.1038/s41550-020-01222-x. S2CID 228954129. Archived from the original on 27 October 2020. Retrieved 26 October 2020.
- Hayne, P.O.; et al. (26 October 2020). "Micro cold traps on the Moon". Nature Astronomy. 5 (2): 169–175. arXiv:2005.05369. Bibcode:2021NatAs...5..169H. doi:10.1038/s41550-020-1198-9. S2CID 218595642. Archived from the original on 27 October 2020. Retrieved 26 October 2020.
- Guarino, Ben; Achenbach, Joel (26 October 2020). "Pair of studies confirm there is water on the moon – New research confirms what scientists had theorized for years — the moon is wet". The Washington Post. Archived from the original on 26 October 2020. Retrieved 26 October 2020.
- Chang, Kenneth (26 October 2020). "There's Water and Ice on the Moon, and in More Places Than NASA Once Thought – Future astronauts seeking water on the moon may not need to go into the most treacherous craters in its polar regions to find it". The New York Times. Archived from the original on 26 October 2020. Retrieved 26 October 2020.
- Matt Williams (10 July 2017). "How Long is a Day on the Moon?". Archived from the original on 29 November 2020. Retrieved 5 December 2020.
- Stern, David (30 March 2014). "Libration of the Moon". NASA. Archived from the original on 22 May 2020. Retrieved 11 February 2020.
- Haigh, I. D.; Eliot, M.; Pattiaratchi, C. (2011). "Global influences of the 18.61 year nodal cycle and 8.85 year cycle of lunar perigee on high tidal levels" (PDF). J. Geophys. Res. 116 (C6): C06025. Bibcode:2011JGRC..116.6025H. doi:10.1029/2010JC006645. Archived (PDF) from the original on 12 December 2019. Retrieved 24 September 2019.
- V V Belet︠s︡kiĭ (2001). Essays on the Motion of Celestial Bodies. Birkhäuser. p. 183. ISBN 978-3-7643-5866-2. Archived from the original on 23 March 2018. Retrieved 22 August 2020.
- Touma, Jihad; Wisdom, Jack (1994). "Evolution of the Earth-Moon system". The Astronomical Journal. 108 (5): 1943–1961. Bibcode:1994AJ....108.1943T. doi:10.1086/117209.
- Iain Todd (31 March 2018). "Is the Moon maintaining Earth's magnetism?". BBC Sky at Night Magazine. Archived from the original on 22 September 2020. Retrieved 16 November 2020.
- Latham, Gary; Ewing, Maurice; Dorman, James; Lammlein, David; Press, Frank; Toksőz, Naft; Sutton, George; Duennebier, Fred; Nakamura, Yosio (1972). "Moonquakes and lunar tectonism". Earth, Moon, and Planets. 4 (3–4): 373–382. Bibcode:1972Moon....4..373L. doi:10.1007/BF00562004. S2CID 120692155.
- Lambeck, K. (1977). "Tidal Dissipation in the Oceans: Astronomical, Geophysical and Oceanographic Consequences". Philosophical Transactions of the Royal Society A. 287 (1347): 545–594. Bibcode:1977RSPTA.287..545L. doi:10.1098/rsta.1977.0159. S2CID 122853694.
- Le Provost, C.; Bennett, A.F.; Cartwright, D.E. (1995). "Ocean Tides for and from TOPEX/POSEIDON". Science. 267 (5198): 639–642. Bibcode:1995Sci...267..639L. doi:10.1126/science.267.5198.639. PMID 17745840. S2CID 13584636.
- Chapront, J.; Chapront-Touzé, M.; Francou, G. (2002). "A new determination of lunar orbital parameters, precession constant and tidal acceleration from LLR measurements". Astronomy and Astrophysics. 387 (2): 700–709. Bibcode:2002A&A...387..700C. doi:10.1051/0004-6361:20020420. S2CID 55131241.
- "Why the Moon is getting further away from Earth". BBC News. 1 February 2011. Archived from the original on 25 September 2015. Retrieved 18 September 2015.
- Williams, James G.; Boggs, Dale H. (2016). "Secular tidal changes in lunar orbit and Earth rotation". Celestial Mechanics and Dynamical Astronomy. 126 (1): 89–129. Bibcode:2016CeMDA.126...89W. doi:10.1007/s10569-016-9702-3. ISSN 1572-9478. S2CID 124256137. Archived from the original on 30 July 2022. Retrieved 30 July 2022.
- Ray, R. (15 May 2001). "Ocean Tides and the Earth's Rotation". IERS Special Bureau for Tides. Archived from the original on 27 March 2010. Retrieved 17 March 2010.
- Stephenson, F. R.; Morrison, L. V.; Hohenkerk, C. Y. (2016). "Measurement of the Earth's rotation: 720 BC to AD 2015". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 472 (2196): 20160404. Bibcode:2016RSPSA.47260404S. doi:10.1098/rspa.2016.0404. PMC 5247521. PMID 28119545.
- Morrison, L. V.; Stephenson, F. R.; Hohenkerk, C. Y.; Zawilski, M. (2021). "Addendum 2020 to 'Measurement of the Earth's rotation: 720 BC to AD 2015'". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 477 (2246): 20200776. Bibcode:2021RSPSA.47700776M. doi:10.1098/rspa.2020.0776. S2CID 231938488. Archived from the original on 23 June 2022. Retrieved 30 July 2022.
- "When Will Earth Lock to the Moon?". Universe Today. 12 April 2016. Archived from the original on 28 May 2022. Retrieved 5 January 2022.
- Murray, C.D.; Dermott, Stanley F. (1999). Solar System Dynamics. Cambridge University Press. p. 184. ISBN 978-0-521-57295-8.
- Dickinson, Terence (1993). From the Big Bang to Planet X. Camden East, Ontario: Camden House. pp. 79–81. ISBN 978-0-921820-71-0.
- Phil Plait. "Dark Side of the Moon". Bad Astronomy: Misconceptions. Archived from the original on 12 April 2010. Retrieved 15 February 2010.
- Alexander, M.E. (1973). "The Weak Friction Approximation and Tidal Evolution in Close Binary Systems". Astrophysics and Space Science. 23 (2): 459–508. Bibcode:1973Ap&SS..23..459A. doi:10.1007/BF00645172. S2CID 122918899.
- "Moon used to spin 'on different axis'". BBC News. BBC. 23 March 2016. Archived from the original on 23 March 2016. Retrieved 23 March 2016.
- "Moonlight helps plankton escape predators during Arctic winters". New Scientist. 16 January 2016. Archived from the original on 30 January 2016.
- Howells, Kate (25 September 2020). "Can the Moon be upside down?". The Planetary Society. Archived from the original on 2 January 2022. Retrieved 2 January 2022.
- Spekkens, K. (18 October 2002). "Is the Moon seen as a crescent (and not a "boat") all over the world?". Curious About Astronomy. Archived from the original on 16 October 2015. Retrieved 28 September 2015.
- Hershenson, Maurice (1989). The Moon illusion. Routledge. p. 5. ISBN 978-0-8058-0121-7.
- Luciuk, Mike. "How Bright is the Moon?". Amateur Astronomers. Archived from the original on 12 March 2010. Retrieved 16 March 2010.
- "Colors of the Moon". Science Mission Directorate. 11 November 2020. Archived from the original on 9 April 2022. Retrieved 9 April 2022.
- Gibbs, Philip (May 1997). "Why is the sky blue?". math.ucr.edu. Archived from the original on 2 November 2015. Retrieved 4 November 2015.
... may cause the moon to have a blue tinge since the red light has been scattered out.
- Taylor, G. J. (8 November 2006). "Recent Gas Escape from the Moon". Planetary Science Research Discoveries: 110. Bibcode:2006psrd.reptE.110T. Archived from the original on 4 March 2007. Retrieved 4 April 2007.
- Schultz, P. H.; Staid, M. I.; Pieters, C. M. (2006). "Lunar activity from recent gas release". Nature. 444 (7116): 184–186. Bibcode:2006Natur.444..184S. doi:10.1038/nature05303. PMID 17093445. S2CID 7679109.
- Gunn, Dr. Alastair (2022). "Why is the Moon sometimes visible during the day?". BBC Science Focus Magazine. BBC. Archived from the original on 21 January 2022. Retrieved 28 June 2022.
- "Supermoon November 2016". Space.com. 13 November 2016. Archived from the original on 14 November 2016. Retrieved 14 November 2016.
- Tony Phillips (16 March 2011). "Super Full Moon". NASA. Archived from the original on 7 May 2012. Retrieved 19 March 2011.
- Richard K. De Atley (18 March 2011). "Full moon tonight is as close as it gets". The Press-Enterprise. Archived from the original on 22 March 2011. Retrieved 19 March 2011.
- "'Super moon' to reach closest point for almost 20 years". The Guardian. 19 March 2011. Archived from the original on 25 December 2013. Retrieved 19 March 2011.
- Georgia State University, Dept. of Physics (Astronomy). "Perceived Brightness". Brightnes and Night/Day Sensitivity. Georgia State University. Archived from the original on 21 February 2014. Retrieved 25 January 2014.
- Lutron. "Measured light vs. perceived light" (PDF). From IES Lighting Handbook 2000, 27–4. Lutron. Archived (PDF) from the original on 5 February 2013. Retrieved 25 January 2014.
Walker, John (May 1997). "Inconstant Moon". Earth and Moon Viewer. Fourth paragraph of "How Bright the Moonlight": Fourmilab. Archived from the original on 14 December 2013. Retrieved 23 January 2014.
14% [...] due to the logarithmic response of the human eye.
- Espenak, F. (2000). "Solar Eclipses for Beginners". MrEclip. Archived from the original on 24 May 2015. Retrieved 17 March 2010.
- Walker, John (10 July 2004). "Moon near Perigee, Earth near Aphelion". Fourmilab. Archived from the original on 8 December 2013. Retrieved 25 December 2013.
- Thieman, J.; Keating, S. (2 May 2006). "Eclipse 99, Frequently Asked Questions". NASA. Archived from the original on 11 February 2007. Retrieved 12 April 2007.
- Espenak, F. "Saros Cycle". NASA. Archived from the original on 30 October 2007. Retrieved 17 March 2010.
- Guthrie, D.V. (1947). "The Square Degree as a Unit of Celestial Area". Popular Astronomy. Vol. 55. pp. 200–203. Bibcode:1947PA.....55..200G.
- "Total Lunar Occultations". Royal Astronomical Society of New Zealand. Archived from the original on 23 February 2010. Retrieved 17 March 2010.
- Burton, David M. (2011). The History of Mathematics: An Introduction. Mcgraw-Hill. p. 3. ISBN 9780077419219.
- "Lunar maps". Archived from the original on 1 June 2019. Retrieved 18 September 2019.
- "Carved and Drawn Prehistoric Maps of the Cosmos". Space Today. 2006. Archived from the original on 5 March 2012. Retrieved 12 April 2007.
- O'Connor, J.J.; Robertson, E.F. (February 1999). "Anaxagoras of Clazomenae". University of St Andrews. Archived from the original on 12 January 2012. Retrieved 12 April 2007.
- Needham, Joseph (1986). Science and Civilization in China, Volume III: Mathematics and the Sciences of the Heavens and Earth. Taipei: Caves Books. ISBN 978-0-521-05801-8. Archived from the original on 22 June 2019. Retrieved 22 August 2020.
- Aaboe, A.; Britton, J.P.; Henderson, J.A.; Neugebauer, Otto; Sachs, A.J. (1991). "Saros Cycle Dates and Related Babylonian Astronomical Texts". Transactions of the American Philosophical Society. 81 (6): 1–75. doi:10.2307/1006543. JSTOR 1006543.
One comprises what we have called "Saros Cycle Texts", which give the months of eclipse possibilities arranged in consistent cycles of 223 months (or 18 years).
- Sarma, K.V. (2008). "Astronomy in India". In Helaine Selin (ed.). Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Encyclopaedia of the History of Science (2 ed.). Springer. pp. 317–321. Bibcode:2008ehst.book.....S. ISBN 978-1-4020-4559-2.
- Lewis, C.S. (1964). The Discarded Image. Cambridge: Cambridge University Press. p. 108. ISBN 978-0-521-47735-2. Archived from the original on 17 June 2020. Retrieved 11 November 2019.
- "Discovering How Greeks Computed in 100 B.C." The New York Times. 31 July 2008. Archived from the original on 4 December 2013. Retrieved 9 March 2014.
- van der Waerden, Bartel Leendert (1987). "The Heliocentric System in Greek, Persian and Hindu Astronomy". Annals of the New York Academy of Sciences. 500 (1): 1–569. Bibcode:1987NYASA.500....1A. doi:10.1111/j.1749-6632.1987.tb37193.x. PMID 3296915. S2CID 84491987.
- Evans, James (1998). The History and Practice of Ancient Astronomy. Oxford & New York: Oxford University Press. pp. 71, 386. ISBN 978-0-19-509539-5.
- Robertson, E.F. (November 2000). "Aryabhata the Elder". Scotland: School of Mathematics and Statistics, University of St Andrews. Archived from the original on 11 July 2015. Retrieved 15 April 2010.
- A.I. Sabra (2008). "Ibn Al-Haytham, Abū ʿAlī Al-Ḥasan Ibn Al-Ḥasan". Dictionary of Scientific Biography. Detroit: Charles Scribner's Sons. pp. 189–210, at 195.
- Van Helden, A. (1995). "The Moon". Galileo Project. Archived from the original on 23 June 2004. Retrieved 12 April 2007.
- Consolmagno, Guy J. (1996). "Astronomy, Science Fiction and Popular Culture: 1277 to 2001 (And beyond)". Leonardo. 29 (2): 127–132. doi:10.2307/1576348. JSTOR 1576348. S2CID 41861791.
- Hall, R. Cargill (1977). "Appendix A: Lunar Theory Before 1964". NASA History Series. Lunar Impact: A History of Project Ranger. Washington, DC: Scientific and Technical Information Office, NASA. Archived from the original on 10 April 2010. Retrieved 13 April 2010.
- Zak, Anatoly (2009). "Russia's unmanned missions toward the Moon". Archived from the original on 14 April 2010. Retrieved 20 April 2010.
- Coren, M. (26 July 2004). "'Giant leap' opens world of possibility". CNN. Archived from the original on 20 January 2012. Retrieved 16 March 2010.
- "Record of Lunar Events, 24 July 1969". Apollo 11 30th anniversary. NASA. Archived from the original on 8 April 2010. Retrieved 13 April 2010.
- "Manned Space Chronology: Apollo_11". Spaceline.org. Archived from the original on 14 February 2008. Retrieved 6 February 2008.
- "Apollo Anniversary: Moon Landing "Inspired World"". National Geographic. Archived from the original on 9 February 2008. Retrieved 6 February 2008.
- Orloff, Richard W. (September 2004) [First published 2000]. "Extravehicular Activity". Apollo by the Numbers: A Statistical Reference. NASA History Division, Office of Policy and Plans. The NASA History Series. Washington, DC: NASA. ISBN 978-0-16-050631-4. LCCN 00061677. NASA SP-2000-4029. Archived from the original on 6 June 2013. Retrieved 1 August 2013.
- "NASA news release 77-47 page 242" (PDF) (Press release). 1 September 1977. Archived (PDF) from the original on 4 June 2011. Retrieved 16 March 2010.
- Appleton, James; Radley, Charles; Deans, John; Harvey, Simon; Burt, Paul; Haxell, Michael; Adams, Roy; Spooner N.; Brieske, Wayne (1977). "NASA Turns A Deaf Ear To The Moon". OASI Newsletters Archive. Archived from the original on 10 December 2007. Retrieved 29 August 2007.
- Dickey, J.; Bender, P. L.; Faller, J. E.; Newhall, X. X.; Ricklefs, R. L.; Ries, J. G.; Shelus, P. J.; Veillet, C.; Whipple, A. L. (1994). "Lunar laser ranging: a continuing legacy of the Apollo program". Science. 265 (5171): 482–490. Bibcode:1994Sci...265..482D. doi:10.1126/science.265.5171.482. PMID 17781305. S2CID 10157934. Archived from the original on 19 August 2020. Retrieved 2 December 2019.
- "Rocks and Soils from the Moon". NASA. Archived from the original on 27 May 2010. Retrieved 6 April 2010.
- "Hiten-Hagomoro". NASA. Archived from the original on 14 June 2011. Retrieved 29 March 2010.
- "Clementine information". NASA. 1994. Archived from the original on 25 September 2010. Retrieved 29 March 2010.
- "Lunar Prospector: Neutron Spectrometer". NASA. 2001. Archived from the original on 27 May 2010. Retrieved 29 March 2010.
- "SMART-1 factsheet". European Space Agency. 26 February 2007. Archived from the original on 23 March 2010. Retrieved 29 March 2010.
- "Chang'e 1". NASA. 2019. Archived from the original on 22 November 2021. Retrieved 3 October 2021.
- "Mission Sequence". Indian Space Research Organisation. 17 November 2008. Archived from the original on 6 July 2010. Retrieved 13 April 2010.
- "Lunar CRater Observation and Sensing Satellite (LCROSS): Strategy & Astronomer Observation Campaign". NASA. October 2009. Archived from the original on 1 January 2012. Retrieved 13 April 2010.
- David, Leonard (17 March 2015). "China Outlines New Rockets, Space Station and Moon Plans". Space.com. Archived from the original on 1 July 2016. Retrieved 29 June 2016.
- "China's Chang'e-5 brought 1,731 grams of samples from the moon". The Hindu. 20 December 2020. Archived from the original on 29 October 2021. Retrieved 15 October 2021.
- Mann, Adam (July 2019). "NASA's Artemis Program". Space.com. Archived from the original on 17 April 2021. Retrieved 19 April 2021.
- "The Space Review: The Artemis Accords: repeating the mistakes of the Age of Exploration". The Space Review. 29 June 2020. Archived from the original on 25 January 2022. Retrieved 1 February 2022.
- "Australia Between the Moon Agreement and the Artemis Accords". Australian Institute of International Affairs. 2 June 2021. Archived from the original on 1 February 2022. Retrieved 1 February 2022.
- "The Space Treaty Institute – Dedicated to Peace and Sustainability in Outer Space. Our Mission: To give people Hope and Inspiration by helping the nations of Earth to build a Common Future". The Space Treaty Institute – Dedicated to Peace and Sustainability in Outer Space. Our Mission. Archived from the original on 1 February 2022. Retrieved 1 February 2022.
- "President Bush Offers New Vision For NASA" (Press release). NASA. 14 December 2004. Archived from the original on 10 May 2007. Retrieved 12 April 2007.
- "NASA plans to send first woman on Moon by 2024". The Asian Age. 15 May 2019. Archived from the original on 14 April 2020. Retrieved 15 May 2019.
- Covault, C. (4 June 2006). "Russia Plans Ambitious Robotic Lunar Mission". Aviation Week. Archived from the original on 12 June 2006. Retrieved 12 April 2007.
- "India's Space Agency Proposes Manned Spaceflight Program". Space.com. 10 November 2006. Archived from the original on 11 April 2012. Retrieved 23 October 2008.
- Garber, Megan (19 December 2012). "The Trash We've Left on the Moon". The Atlantic. Archived from the original on 9 April 2022. Retrieved 11 April 2022.
- Vidaurri, Monica (24 October 2019). "Will people go to space—and then colonize it?". Quartz. Archived from the original on 9 November 2021. Retrieved 9 November 2021.
- David, Leonard (21 August 2020). "Cold as (lunar) ice: Protecting the moon's polar regions from contamination". Space.com. Archived from the original on 4 February 2022. Retrieved 3 February 2022.
- Gorman, Alice (1 July 2022). "#SpaceWatchGL Opinion: An ecofeminist approach to the sustainable use of the Moon". SpaceWatch.Global. Archived from the original on 4 July 2022. Retrieved 3 July 2022. Note: see Val Plumwood which Alice Gorman cites regarding co-participation.
- Alvarez, Tamara (1 January 2020). The Eighth Continent: An Ethnography of Twenty-First Century Euro-American Plans to Settle the Moon (Thesis). p. 109-115, 164–167, 176. Archived from the original on 5 February 2022. Retrieved 1 November 2021.
- Carter, Jamie (27 February 2022). "As Chinese Rocket Strikes Moon This Week We Need To Act Now To Prevent New Space Junk Around The Moon Say Scientists". Forbes. Archived from the original on 9 April 2022. Retrieved 9 April 2022.
- "Space: The Final Frontier of Environmental Disasters?". Wired. 15 July 2013. Archived from the original on 14 July 2021. Retrieved 9 April 2022.
- Pino, Paolo; Salmeri, Antonino; Hugo, Adam; Hume, Shayna (27 August 2021). "Waste Management for Lunar Resources Activities: Toward a Circular Lunar Economy". New Space. Mary Ann Liebert Inc. 10 (3): 274–283. doi:10.1089/space.2021.0012. ISSN 2168-0256. S2CID 233335692.
- Briggs, Randall; Sacco, Albert (1985). "1985lbsa.conf..423B Page 423". Lunar Bases and Space Activities of the 21St Century (in Finnish): 423. Bibcode:1985lbsa.conf..423B. Archived from the original on 26 May 2022. Retrieved 26 May 2022.
- Andrew Jones (23 September 2020). "China's Chang'e 3 lunar lander still going strong after 7 years on the moon". Space.com. Archived from the original on 25 November 2020. Retrieved 16 November 2020.
- Takahashi, Yuki (September 1999). "Mission Design for Setting up an Optical Telescope on the Moon". California Institute of Technology. Archived from the original on 6 November 2015. Retrieved 27 March 2011.
- Chandler, David (15 February 2008). "MIT to lead development of new telescopes on moon". MIT News. Archived from the original on 4 March 2009. Retrieved 27 March 2011.
- Naeye, Robert (6 April 2008). "NASA Scientists Pioneer Method for Making Giant Lunar Telescopes". Goddard Space Flight Center. Archived from the original on 22 December 2010. Retrieved 27 March 2011.
- Bell, Trudy (9 October 2008). "Liquid Mirror Telescopes on the Moon". Science News. NASA. Archived from the original on 23 March 2011. Retrieved 27 March 2011.
- "Far Ultraviolet Camera/Spectrograph". Lpi.usra.edu. Archived from the original on 3 December 2013. Retrieved 3 October 2013.
- "Mission Report: Apollo 17 – The Most Productive Lunar Expedition" (PDF). NASA. Archived from the original (PDF) on 30 September 2006. Retrieved 10 February 2021.
- David, Leonard (21 October 2019). "Moon Dust Could Be a Problem for Future Lunar Explorers". Space.com. Archived from the original on 1 December 2020. Retrieved 26 November 2020.
- Zheng, William (15 January 2019). "Chinese lunar lander's cotton seeds spring to life on far side of the moon". South China Morning Post. Archived from the original on 16 January 2019. Retrieved 26 November 2020.
- "Can any State claim a part of outer space as its own?". United Nations Office for Outer Space Affairs. Archived from the original on 21 April 2010. Retrieved 28 March 2010.
- "The treaties control space-related activities of States. What about non-governmental entities active in outer space, like companies and even individuals?". United Nations Office for Outer Space Affairs. Archived from the original on 21 April 2010. Retrieved 28 March 2010.
- "Statement by the Board of Directors of the IISL On Claims to Property Rights Regarding The Moon and Other Celestial Bodies (2004)" (PDF). International Institute of Space Law. 2004. Archived from the original (PDF) on 22 December 2009. Retrieved 28 March 2010.
- "Further Statement by the Board of Directors of the IISL On Claims to Lunar Property Rights (2009)" (PDF). International Institute of Space Law. 22 March 2009. Archived from the original (PDF) on 22 December 2009. Retrieved 28 March 2010.
- "Do the five international treaties regulate military activities in outer space?". United Nations Office for Outer Space Affairs. Archived from the original on 21 April 2010. Retrieved 28 March 2010.
- "How many States have signed and ratified the five international treaties governing outer space?". United Nations Office for Outer Space Affairs. 1 January 2006. Archived from the original on 21 April 2010. Retrieved 28 March 2010.
- "The Space Review: Is outer space a de jure common-pool resource?". The Space Review. 25 October 2021. Archived from the original on 2 November 2021. Retrieved 9 April 2022.
- "Agreement Governing the Activities of States on the Moon and Other Celestial Bodies". United Nations Office for Outer Space Affairs. Archived from the original on 9 August 2010. Retrieved 28 March 2010.
- Vazhapully, Kiran (22 July 2020). "Space Law at the Crossroads: Contextualizing the Artemis Accords and the Space Resources Executive Order". OpinioJuris. Archived from the original on 10 May 2021. Retrieved 10 May 2021.
- "Administration Statement on Executive Order on Encouraging International Support for the Recovery and Use of Space Resources". SpaceRef.com. White House. 6 April 2020. Retrieved 17 June 2020.
- "'One Small Step' Act Encourages Protection of Human Heritage in Space". HowStuffWorks. 12 January 2021. Archived from the original on 1 November 2021. Retrieved 1 November 2021.
- "Moonkind – Human Heritage in Outer Space". For All Moonkind. Archived from the original on 1 November 2021. Retrieved 1 November 2021.
- "Declaration of the Rights of the Moon". Australian Earth Laws Alliance. 11 February 2021. Archived from the original on 23 April 2021. Retrieved 10 May 2021.
- Tepper, Eytan; Whitehead, Christopher (1 December 2018). "Moon, Inc.: The New Zealand Model of Granting Legal Personality to Natural Resources Applied to Space". New Space. 6 (4): 288–298. Bibcode:2018NewSp...6..288T. doi:10.1089/space.2018.0025. ISSN 2168-0256. S2CID 158616075. Archived from the original on 28 June 2021. Retrieved 30 July 2022.
- Evans, Kate (20 July 2021). "Hear Ye! Hear Ye! A Declaration of the Rights of the Moon". Eos. Archived from the original on 6 February 2022. Retrieved 9 April 2022.
- Thompson, William Irwin. (1981). The time falling bodies take to light : mythology, sexuality, and the origins of culture. New York: St. Martin's Press. p. 105. ISBN 0-312-80510-1. OCLC 6890108. Archived from the original on 3 October 2021. Retrieved 30 July 2022.
- Boyle, Rebecca (9 July 2019). "Ancient humans used the moon as a calendar in the sky". Science News. Archived from the original on 4 November 2021. Retrieved 4 November 2021.
- Brooks, A. S.; Smith, C. C. (1987). "Ishango revisited: new age determinations and cultural interpretations". The African Archaeological Review. 5: 65–78. doi:10.1007/BF01117083. JSTOR 25130482. S2CID 129091602.
- Duncan, David Ewing (1998). The Calendar. Fourth Estate Ltd. pp. 10–11. ISBN 978-1-85702-721-1.
- Zerubavel, E. (1989). The Seven Day Circle: The History and Meaning of the Week. University of Chicago Press. p. 9. ISBN 978-0-226-98165-9. Archived from the original on 25 July 2022. Retrieved 25 February 2022.
- Smith, William George (1849). Dictionary of Greek and Roman Biography and Mythology: Oarses-Zygia. Vol. 3. J. Walton. p. 768. Archived from the original on 26 November 2020. Retrieved 29 March 2010.
- Estienne, Henri (1846). Thesaurus graecae linguae. Vol. 5. Didot. p. 1001. Archived from the original on 28 July 2020. Retrieved 29 March 2010.
- mensis. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project.
- μείς in Liddell and Scott.
- Mallory, J.P.; Adams, D.Q. (2006). The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World. Oxford Linguistics. Oxford University Press. pp. 98, 128, 317. ISBN 978-0-19-928791-8.
- Harper, Douglas. "measure". Online Etymology Dictionary.
- Harper, Douglas. "menstrual". Online Etymology Dictionary.
- Ilyas, Mohammad (March 1994). "Lunar Crescent Visibility Criterion and Islamic Calendar". Quarterly Journal of the Royal Astronomical Society. 35: 425. Bibcode:1994QJRAS..35..425L.
- "Mid-Autumn Festival Celebration". Confucius Institute for Scotland. 30 August 2022. Retrieved 22 November 2022.
- "Cylinder vase". Collections Search – Museum of Fine Arts, Boston. 20 May 1987. Archived from the original on 11 November 2021. Retrieved 11 November 2021.
- Hart, G. (2005). The Routledge Dictionary of Egyptian Gods and Goddesses. Routledge Dictionaries. Taylor & Francis. p. 77. ISBN 978-1-134-28424-5. Archived from the original on 25 July 2022. Retrieved 23 February 2022.
- Black, Jeremy; Green, Anthony (1992). Gods, Demons and Symbols of Ancient Mesopotamia: An Illustrated Dictionary. The British Museum Press. p. 135. ISBN 978-0-7141-1705-8. Archived from the original on 19 August 2020. Retrieved 28 October 2017.
- Nemet-Nejat, Karen Rhea (1998), Daily Life in Ancient Mesopotamia, Daily Life, Greenwood, p. 203, ISBN 978-0-313-29497-6, archived from the original on 16 June 2020, retrieved 11 June 2019
- Zschietzschmann, W. (2006). Hellas and Rome: The Classical World in Pictures. Whitefish, Montana: Kessinger Publishing. p. 23. ISBN 978-1-4286-5544-7.
- Cohen, Beth (2006). "Outline as a Special Technique in Black- and Red-figure Vase-painting". The Colors of Clay: Special Techniques in Athenian Vases. Los Angeles: Getty Publications. pp. 178–179. ISBN 978-0-89236-942-3. Archived from the original on 19 August 2020. Retrieved 28 April 2020.
- "It seems possible, though not certain, that after the conquest Mehmed took over the crescent and star as an emblem of sovereignty from the Byzantines. The half-moon alone on a blood red flag, allegedly conferred on the Janissaries by Emir Orhan, was much older, as is demonstrated by numerous references to it dating from before 1453. But since these flags lack the star, which along with the half-moon is to be found on Sassanid and Byzantine municipal coins, it may be regarded as an innovation of Mehmed. It seems certain that in the interior of Asia tribes of Turkish nomads had been using the half-moon alone as an emblem for some time past, but it is equally certain that crescent and star together are attested only for a much later period. There is good reason to believe that old Turkish and Byzantine traditions were combined in the emblem of Ottoman and, much later, present-day Republican Turkish sovereignty." Franz Babinger (William C. Hickman Ed., Ralph Manheim Trans.), Mehmed the Conqueror and His Time, Princeton University Press, 1992, p 108
- Kadoi, Yuka (1 October 2014). "Crescent (symbol of Islam)". Brill Encyclopedia of Islam Online. Archived from the original on 8 April 2022. Retrieved 8 April 2022.
- "Muhammad." Encyclopædia Britannica. 2007. Encyclopædia Britannica Online, p.13
- Abbri, Ferdinando (30 August 2019). "Gold and silver: perfection of metals in medieval and early modern alchemy". Substantia: 39–44. doi:10.13128/Substantia-603. ISSN 2532-3997. Archived from the original on 17 June 2022. Retrieved 8 April 2022.
- "The Moon of Science or the Moon of Lovers?". The MIT Press Reader. 29 September 2020. Archived from the original on 1 November 2021. Retrieved 1 November 2021.
- "Imagining the Moon". The New York Times. 9 July 2019. Archived from the original on 9 July 2019. Retrieved 4 November 2021.
- Seed, David (9 July 2019). "Moon on the mind: two millennia of lunar literature". Nature. 571 (7764): 172–173. Bibcode:2019Natur.571..172S. doi:10.1038/d41586-019-02090-w. S2CID 195847287. Archived from the original on 21 December 2021. Retrieved 1 November 2021.
- "Polycentricity for Governance of the Moon as a Commons". Open Lunar Foundation. 22 March 2022. Archived from the original on 20 April 2022. Retrieved 9 April 2022.
- Lilienfeld, Scott O.; Arkowitz, Hal (2009). "Lunacy and the Full Moon". Scientific American. Archived from the original on 16 October 2009. Retrieved 13 April 2010.
- Rotton, James; Kelly, I.W. (1985). "Much ado about the full moon: A meta-analysis of lunar-lunacy research". Psychological Bulletin. 97 (2): 286–306. doi:10.1037/0033-2909.97.2.286. PMID 3885282.
- Martens, R.; Kelly, I.W.; Saklofske, D.H. (1988). "Lunar Phase and Birthrate: A 50-year Critical Review". Psychological Reports. 63 (3): 923–934. doi:10.2466/pr0.19220.127.116.113. PMID 3070616. S2CID 34184527.
- Kelly, Ivan; Rotton, James; Culver, Roger (1986), "The Moon Was Full and Nothing Happened: A Review of Studies on the Moon and Human Behavior", Skeptical Inquirer, 10 (2): 129–143. Reprinted in The Hundredth Monkey – and other paradigms of the paranormal, edited by Kendrick Frazier, Prometheus Books. Revised and updated in The Outer Edge: Classic Investigations of the Paranormal, edited by Joe Nickell, Barry Karr, and Tom Genoni, 1996, CSICOP.
- Foster, Russell G.; Roenneberg, Till (2008). "Human Responses to the Geophysical Daily, Annual and Lunar Cycles". Current Biology. 18 (17): R784–R794. doi:10.1016/j.cub.2008.07.003. PMID 18786384. S2CID 15429616.
- Angier, Natalie (7 September 2014). "The Moon Comes Around Again". The New York Times. Archived from the original on 8 September 2014. Retrieved 8 September 2014.
- "The Moon". Discovery 2008. BBC World Service. Archived from the original on 11 March 2011. Retrieved 9 May 2021.
- Bussey, B.; Spudis, P.D. (2004). The Clementine Atlas of the Moon. Cambridge University Press. ISBN 978-0-521-81528-4.
- Cain, Fraser. "Where does the Moon Come From?". Universe Today. Archived from the original on 10 May 2021. Retrieved 9 May 2021. (podcast and transcript)
- Jolliff, B. (2006). Wieczorek, M.; Shearer, C.; Neal, C. (eds.). New views of the Moon. Reviews in Mineralogy and Geochemistry. Vol. 60. Chantilly, Virginia: Mineralogy Society of America. p. 721. Bibcode:2006RvMG...60D...5J. doi:10.2138/rmg.2006.60.0. ISBN 978-0-939950-72-0. Archived from the original on 27 June 2007. Retrieved 12 April 2007.
- Jones, E. M. (2006). "Apollo Lunar Surface Journal". NASA. Archived from the original on 8 May 2021. Retrieved 9 May 2021.
- "Exploring the Moon". Lunar and Planetary Institute. Archived from the original on 10 May 2021. Retrieved 9 May 2021.
- Mackenzie, Dana (2003). The Big Splat, or How Our Moon Came to Be. Hoboken, NJ: John Wiley & Sons. ISBN 978-0-471-15057-2. Archived from the original on 17 June 2020. Retrieved 11 June 2019.
- Moore, P. (2001). On the Moon. Tucson, Arizona: Sterling Publishing Co. ISBN 978-0-304-35469-6.
- "Moon Articles". Planetary Science Research Discoveries. Hawai'i Institute of Geophysics and Planetology. Archived from the original on 17 November 2015. Retrieved 18 November 2006.
- Spudis, P.D. (1996). The Once and Future Moon. Smithsonian Institution Press. ISBN 978-1-56098-634-8. Archived from the original on 17 June 2020. Retrieved 11 June 2019.
- Taylor, S.R. (1992). Solar system evolution. Cambridge University Press. p. 307. ISBN 978-0-521-37212-1.
- Teague, K. (2006). "The Project Apollo Archive". Archived from the original on 4 April 2007. Retrieved 12 April 2007.
- Wilhelms, D.E. (1987). "Geologic History of the Moon". U.S. Geological Survey Professional Paper. Professional Paper. 1348. doi:10.3133/pp1348. Archived from the original on 23 February 2019. Retrieved 12 April 2007.
- Wilhelms, D.E. (1993). To a Rocky Moon: A Geologist's History of Lunar Exploration. Tucson: University of Arizona Press. ISBN 978-0-8165-1065-8. Archived from the original on 17 June 2020. Retrieved 10 March 2009.
- NASA images and videos about the Moon
- Albums of images and high-resolution overflight videos by Seán Doran, based on LROC data, on Flickr and YouTube
- on YouTube
- on YouTube
- Unified Geologic Map of the Moon – United States Geological Survey
- Moon Trek – An integrated map browser of datasets and maps for the Moon
- The Moon on Google Maps, a 3-D rendition of the Moon akin to Google Earth
- "Consolidated Lunar Atlas". Lunar and Planetary Institute. Retrieved 26 February 2012.
- Gazetteer of Planetary Nomenclature (USGS) List of feature names.
- "Clementine Lunar Image Browser". U.S. Navy. 15 October 2003. Archived from the original on 7 April 2007. Retrieved 12 April 2007.
- 3D zoomable globes:
- Aeschliman, R. "Lunar Maps". Planetary Cartography and Graphics. Archived from the original on 29 May 2015. Retrieved 12 April 2007. Maps and panoramas at Apollo landing sites
- Japan Aerospace Exploration Agency (JAXA) Kaguya (Selene) images
- Lunar Earthside chart (4497 x 3150px)
- Large image of the Moon's north pole area Archived 23 August 2016 at the Wayback Machine
- "NASA's SKYCAL – Sky Events Calendar". NASA. Archived from the original on 20 August 2007. Retrieved 27 August 2007.
- "Find moonrise, moonset and moonphase for a location". 2008. Retrieved 18 February 2008.
- "HMNAO's Moon Watch". 2005. Archived from the original on 4 February 2009. Retrieved 24 May 2009. See when the next new crescent moon is visible for any location.