Moon
A full moon as seen by an observer on Earth. Full moon is a Lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001
Perigee363,104 km  (0. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand 0024 AU)
Apogee405,696 km  (0. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 0027 AU)
Semi-major axis384,399 km  (0. In Geometry, the semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae 00257 AU[1])
Eccentricity0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 0549[1]
Orbital period27. The orbital period is the time taken for a given object to make one complete Orbit about another object 321582 d  (27 d 7 h 43. A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the The hour (symbol h) is a unit of Time. It is not an SI unit but is accepted for use with the SI 1 min[1])
Synodic period29. A minute is a Unit of measurement of Time or of Angle. The minute is a unit of Time equal to 1/60th of an Hour or 60 The orbital period is the time taken for a given object to make one complete Orbit about another object 530588 d  (29 d 12 h 44. 0 min)
Average orbital speed1. The orbital speed of a body generally a Planet, a Natural satellite, an artificial satellite, or a Multiple star, is the speed at which it 022 km/s
Inclination5. Inclination in general is the Angle between a Reference plane and another plane or axis of direction 145° to the ecliptic[1]
(between 18. This article describes the unit of angle For other meanings see Degree. The ecliptic is the apparent path that the Sun traces out in the sky during the year 29° and 28. 58° to Earth's equator)
Longitude of ascending noderegressing by one revolution in 18. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the The longitude of the ascending node (☊ or Ω is one of the Orbital elements used to specify the Orbit of an object in space In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star 6 years
Argument of perigeeprogressing by one revolution in 8. The argument of periapsis (or argument of perifocus) ( ω) is the Orbital element describing the Angle of an Orbiting body's periapsis 85 years
Satellite ofEarth
Physical characteristics
Mean radius1,737. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 10 km  (0. 273 Earths)[1]
Equatorial radius1,738. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the 14 km  (0. 273 Earths)
Polar radius1,735. A geographical pole, or geographic pole, is either of two fixed points on the surface of a spinning body or Planet, at 90 degrees from the Equator, based 97 km  (0. 273 Earths)
Flattening0. Ellipticity redirects here For the mathematical topic of ellipticity see Elliptic operator. 00125
Circumference10,921 km (equatorial)
Surface area3. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the Equation A spheroid centered at the origin and rotated about the z axis is defined by the implicit equation \left(\frac{x}{a}\right^2+\left(\frac{y}{a}\right^2+\left(\frac{z}{b}\right^2 793×107 km²  (0. Square Kilometre ( US spelling square kilometer) symbol km2, is a decimal multiple of the SI unit of 074 Earths)
Volume2. The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically 1958×1010 k  (0. CM3 redirects here If you were looking for the 3rd game in the Cooking Mama series abbreviated as CM3 see here. 020 Earths)
Mass7. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object 3477×1022 kg  (0. 0123 Earths[1])
Mean density3,346. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 4 kg/m³[1]
Equatorial surface gravity1. Kilogram per cubic metre is the SI measure of Density and is represented as kg/m³ where kg stands for Kilogram and m³ stands for Cubic metre The surface gravity, g, of an astronomical or other object is the Gravitational acceleration experienced at its surface 622 m/s² (0. 1654 g)
Escape velocity2. g-force (also G-force, g-load) is a measurement of an object's Acceleration expressed in g s In Physics, escape velocity is the speed where the Kinetic energy of an object is equal to the magnitude of its Gravitational potential energy 38 km/s
Sidereal rotation
period
27. The rotation period of an astronomical object is the time it takes to complete one revolution around its Axis of rotation relative to the background stars 321582 d (synchronous)
Equatorial rotation velocity4. A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the In Astronomy, synchronous rotation is a planetological term describing a body orbiting another where the orbiting body takes as long to rotate 627 m/s
Axial tilt1. In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. 5424° (to ecliptic)
6. The ecliptic is the apparent path that the Sun traces out in the sky during the year 687° (to orbit plane)
Albedo0. The orbital plane of an object orbiting another is the geometrical plane in which the orbit is embedded. The albedo of an object is the extent to which it diffusely reflects light from the sun 12
Surface temp.
equator
85°N[5]
minmeanmax
100 K220 K390 K
70 K130 K230 K
Apparent magnitude−2. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 5 to −12. 9[2]
−12. 74 (mean full moon)[3]
Angular diameter29. Full moon is a Lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle 3 to 34. 1 arcminutes[3][4]

The Moon (Latin: Luna) is Earth's only natural satellite and the fifth largest natural satellite in the Solar System. A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60 of one degree. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. The tables below of Natural satellites in the Solar System are ordered from largest to smallest by average diameter The Solar System consists of the Sun and those celestial objects bound to it by Gravity.

The average centre-to-centre distance from the Earth to the Moon is 384,403 km, about thirty times the diameter of the Earth. The Moon's diameter is 3,474 km,[6] a little more than a quarter that of the Earth. This means that the Moon's volume is about 2 percent that of Earth and the pull of gravity at its surface about 17 percent that of the Earth. Gravitation is a natural Phenomenon by which objects with Mass attract one another The Moon makes a complete orbit around the Earth every 27. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star 3 days (the orbital period), and the periodic variations in the geometry of the Earth–Moon–Sun system are responsible for the lunar phases that repeat every 29. The orbital period is the time taken for a given object to make one complete Orbit about another object The Sun (Sol is the Star at the center of the Solar System. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth 5 days (the synodic period). The orbital period is the time taken for a given object to make one complete Orbit about another object

The Moon is the only celestial body to which humans have travelled and upon which humans have landed. s are significant physical entities, associations or structures which current Science has confirmed to exist in Space. The first artificial object to escape Earth's gravity and pass near the Moon was the Soviet Union's Luna 1, the first artificial object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Luna 1 (E-1 series also known as Mechta (Мечта lit: Dream) was the first Spacecraft to reach the vicinity Luna 2 (E-1A series was the second of the Soviet Union's Luna program spacecraft launched in the direction of the Moon. Far Side of the Moon, in original French, La face cachée de la lune, is a 2003 film by Robert Lepage. The Soviet spaceprobe Luna 3 (E-3 series was the third spacecraft sent successfully to the Moon and was an early triumph in the human exploration of outer space The first spacecraft to perform a successful lunar soft landing was Luna 9, and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966. Sources [6] The United States (U. The United States of America —commonly referred to as the S. ) Apollo program achieved the only manned missions to date, resulting in six landings between 1969 and 1972. Human exploration of the Moon ceased with the conclusion of the Apollo program, although several countries have announced plans to send people or robotic spacecraft to the Moon.

## Name and etymology

Unlike the moons of other planets, the moon of the Earth has no proper English name other than "the Moon" (capitalized[7]). English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States

The word moon is a Germanic word, related to Latin mensis; it is ultimately a derivative of the Proto-Indo-European root me-, also represented in measure[8] (time), with reminders of its importance in measuring time in words derived from it like Monday, month and menstrual. The Germanic languages are a group of related languages that constitute a branch of the Indo-European (IE Language family. For other uses see Time (disambiguation Time is a component of a measuring system used to sequence events to compare the durations of The month is a unit of Time, used with Calendars which is approximately as long as some natural period related to the motion of the Moon; In English, the word moon exclusively meant "the Moon" until 1665, when it was extended to refer to the recently-discovered natural satellites of other planets. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. [8] The Moon is occasionally referred to by its Latin name, Luna, in order to distinguish it from other natural satellites, with a related adjective lunar, and an adjectival prefix seleno- or suffix -selene (from the Greek deity Selene). Greek mythology is the body of stories belonging to the ancient Greeks concerning their gods and Heroes the nature of the world and the origins and significance In Greek mythology, Selene (Σελήνη " Moon " English sɛˈliːniː was an archaic Lunar deity and the daughter of the Titans

## Lunar surface

Main article: Geology of the Moon

### Two sides of the Moon

The Moon is in synchronous rotation, meaning that it keeps nearly the same face turned towards the Earth at all times. The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar In Astronomy, synchronous rotation is a planetological term describing a body orbiting another where the orbiting body takes as long to rotate Early in the Moon's history, its rotation slowed and became locked in this configuration as a result of frictional effects associated with tidal deformations caused by the Earth. A separate article treats the phenomenon of Tidal resonance in Oceanography. Friction is the Force resisting the relative motion of two Surfaces in contact or a surface in contact with a fluid (e [9]

Long ago when the Moon spun much faster, its tidal bulge preceded the Earth-Moon line because it could not "snap back" its bulges quickly enough to keep its bulges in line with Earth. [10] The rotation swept the bulge beyond the Earth-Moon line. This out-of-line bulge caused a torque, slowing the Moon spin, like a wrench tightening a nut. When the Moon's spin slowed enough to match its orbital rate, then the bulge always faced Earth, the bulge was in line with Earth, and the torque disappeared. That is why the Moon rotates at the same rate as it orbits and we always see the same side of the Moon.

Small variations (libration) in the angle from which the Moon is seen allow about 59% of its surface to be seen from the earth (but only half at any instant). In Astronomy libration (from the Latin verb librare "to balance to sway" cf [6]

 Near side of the Moon Far side of the Moon

The side of the Moon that faces Earth is called the near side, and the opposite side the far side. The near side of the Moon is the Lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the Far side of the Moon Far Side of the Moon, in original French, La face cachée de la lune, is a 2003 film by Robert Lepage. The near side of the Moon is the Lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the Far side of the Moon Far Side of the Moon, in original French, La face cachée de la lune, is a 2003 film by Robert Lepage. The far side is often inaccurately called the "dark side," but in fact, it is illuminated exactly as often as the near side: once per lunar day, during the new moon phase we observe on Earth when the near side is dark. The far side of the Moon was first photographed by the Soviet probe Luna 3 in 1959. The Soviet spaceprobe Luna 3 (E-3 series was the third spacecraft sent successfully to the Moon and was an early triumph in the human exploration of outer space One distinguishing feature of the far side is its almost complete lack of maria. The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions

Lunar libration

### Maria

Main article: Lunar mare

The dark and relatively featureless lunar plains which can clearly be seen with the naked eye are called maria (singular mare), Latin for seas, since they were believed by ancient astronomers to be filled with water. In Astronomy libration (from the Latin verb librare "to balance to sway" cf The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions Historically Astronomy was more concerned with the classification and description of phenomena in the sky while Astrophysics attempted to explain these phenomena These are now known to be vast solidified pools of ancient basaltic lava. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. The majority of these lavas erupted or flowed into the depressions associated with impact basins that formed by the collisions of meteors and comets with the lunar surface. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body (Oceanus Procellarum is a major exception in that it does not correspond to a known impact basin). Oceanus Procellarum (oʊˈsiːənəs ˌprɒsəˈlɛərəm Latin for "Ocean of Storms" is a vast Lunar mare on the western edge of the near side of Maria are found almost exclusively on the near side of the Moon, with the far side having only a few scattered patches covering only about 2% of its surface,[11] compared with about 31% on the near side. [6] The most likely explanation for this difference is related to a higher concentration of heat-producing elements on the near-side hemisphere, as has been demonstrated by geochemical maps obtained from the Lunar Prospector gamma-ray spectrometer. The Lunar Prospector mission was the third selected by NASA for full development and construction as part of the Discovery Program. [12][13] Several provinces containing shield volcanoes and volcanic domes are found within the near side maria. A shield volcano is a large Volcano with shallow-sloping sides A lunar dome is a type of Shield volcano that is found on the surface of the Earth 's Moon. [14]

### Terrae

The lighter-colored regions of the Moon are called terrae, or more commonly just highlands, since they are higher than most maria. Several prominent mountain ranges on the near side are found along the periphery of the giant impact basins, many of which have been filled by mare basalt. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body These are believed to be the surviving remnants of the impact basin's outer rims. [15] In contrast to the Earth, no major lunar mountains are believed to have formed as a result of tectonic events. [16]

From images taken by the Clementine mission in 1994, it appears that four mountainous regions on the rim of the 73 km-wide Peary crater at the Moon's north pole remain illuminated for the entire lunar day. Spacecraft design The spacecraft was an octagonal prism 188 m high and 1 Peary is the closest large lunar Impact crater to the lunar North pole. These peaks of eternal light are possible because of the Moon's extremely small axial tilt to the ecliptic plane. Peak of Eternal Light (PEL describes a point on a body within the Solar System which is eternally bathed in Sunlight. The ecliptic is the apparent path that the Sun traces out in the sky during the year No similar regions of eternal light were found at the south pole, although the rim of Shackleton crater is illuminated for about 80% of the lunar day. The Shackleton crater, named after Ernest Shackleton, a noted explorer of Antarctic lies at the south pole of the Moon. Another consequence of the Moon's small axial tilt is regions that remain in permanent shadow at the bottoms of many polar craters. [17]

### Impact craters

Lunar crater Daedalus on the Moon's far side

The Moon's surface shows obvious evidence of having been affected by impact cratering. Daedalus is a prominent crater located near the center of the far side of the Moon. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body [18] Impact craters form when asteroids and comets collide with the lunar surface, and globally about half a million craters with diameters greater than 1 km can be found. Since impact craters accumulate at a nearly constant rate, the number of craters per unit area superposed on a geologic unit can be used to estimate the age of the surface (see crater counting). Crater counting refers to a method for estimating the age of a planet's surface The lack of an atmosphere, weather and recent geological processes ensures that many of these craters have remained relatively well preserved in comparison to those found on Earth.

The largest crater on the Moon, which also has the distinction of being the largest known crater in the Solar System, is the South Pole-Aitken basin. The South Pole-Aitken basin is an Impact crater on Earth 's Moon. This impact basin is located on the far side, between the South Pole and equator, and is some 2,240 km in diameter and 13 km in depth. [19] Prominent impact basins on the near side include Imbrium, Serenitatis, Crisium, and Nectaris. Mare Imbrium, Latin for "Sea of Showers" or "Sea of Rains" is a vast Lunar mare (mahr'-ay filling a basin on Earth 's Moon Mare Serenitatis (the "sea of serenity" is a Lunar mare that sits just to the east of Mare Imbrium on Earth's moon. Mare Crisium (the "sea of crises" is a Lunar mare located in the Moon 's Crisium basin just northeast of Mare Tranquillitatis. The Sea of Nectar ( Mare Nectaris) is a small Lunar mare or sea (a volcanic lava plain noticeably darker than the rest of the Moon 's surface located

### Regolith

Blanketed atop the Moon's crust is a highly comminuted (broken into ever smaller particles) and "impact gardened" surface layer called regolith. Comminution is one of the four main groups of mechanical processing and describes the movement of the Particle size distribution (grains drops bubbles into a range of finer Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock. Since the regolith forms by impact processes, the regolith of older surfaces is generally thicker than for younger surfaces. In particular, it has been estimated that the regolith varies in thickness from about 3–5 m in the maria, and by about 10–20 m in the highlands. [20] Beneath the finely comminuted regolith layer is what is generally referred to as the megaregolith. This layer is much thicker (on the order of tens of kilometres) and comprises highly fractured bedrock. [21]

### Presence of water

Main article: Lunar ice

The continuous bombardment of the Moon by comets and meteoroids has most likely added small amounts of water to the lunar surface. Lunar ice is water ice that is hypothesised to exist on the surface of the Moon, delivered over geological timescales by the regular bombardment of the Moon by A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — If so, sunlight would split much of this water into its constituent elements of hydrogen and oxygen, both of which would ordinarily escape into space over time, because of the Moon's weak gravity. However, because of the slightness of the axial tilt of the Moon's spin axis to the ecliptic plane—only 1. 5°—some deep craters near the poles never receive direct light from the Sun and are thus in permanent shadow (see Shackleton crater). The Shackleton crater, named after Ernest Shackleton, a noted explorer of Antarctic lies at the south pole of the Moon. Water molecules that ended up in these craters could be stable for long periods of time.

Clementine has mapped craters at the lunar south pole[22] that are shadowed in this way, and computer simulations suggest that up to 14,000 km² might be in permanent shadow. [17] Results from the Clementine mission bistatic radar experiment are consistent with small, frozen pockets of water close to the surface, and data from the Lunar Prospector neutron spectrometer indicate that anomalously high concentrations of hydrogen are present in the upper metre of the regolith near the polar regions. Spacecraft design The spacecraft was an octagonal prism 188 m high and 1 The Lunar Prospector mission was the third selected by NASA for full development and construction as part of the Discovery Program. [23] Estimates for the total quantity of water ice are close to one cubic kilometre.

Water ice can be mined and then split into its constituent hydrogen and oxygen atoms by means of nuclear generators or electric power stations equipped with solar panels. The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation cost-effective, since transporting water from Earth would be prohibitively expensive. The colonization of the Moon is the proposed establishment of permanent human communities on the Moon. However, recent observations made with the Arecibo planetary radar suggest that some of the near-polar Clementine radar data that were previously interpreted as being indicative of water ice might instead be a result of rocks ejected from young impact craters. The Arecibo Observatory is a very sensitive Radio telescope located approximately south-southwest from the town of Arecibo in Puerto Rico. [24] The question of how much water there is on the Moon has not been resolved.

## Physical characteristics

### Internal structure

Schematic illustration of the internal structure of the Moon

The Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and core. The Moon is a differentiated body being composed of a geochemically distinct crust, mantle, and core. In Planetary science, planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical In Geology, a crust is the outermost solid shell of a planet or moon The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided The planetary core consists of the innermost layer(s of a Planet. This structure is believed to have resulted from the fractional crystallization of a magma ocean shortly after its formation about 4. Fractional crystallization is one of the most important geochemical and physical processes operating within the Earth's crust and mantle. According to the Giant impact hypothesis a large amount of energy was liberated in the formation of the Moon and it is predicted that as a result a large portion of the Moon was once completely 5 billion years ago. The energy required to melt the outer portion of the Moon is commonly attributed to a giant impact event that is postulated to have formed the Earth-Moon system, and the subsequent reaccretion of material in Earth orbit. Crystallization of this magma ocean would have given rise to a mafic mantle and a plagioclase-rich crust (see Origin and geologic evolution below). Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric" Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family

Geochemical mapping from orbit implies that the crust of the Moon is largely anorthositic in composition,[25] consistent with the magma ocean hypothesis. Anorthosite (æˈnɔrθəsaɪt/ /ə- is a Phaneritic, Intrusive Igneous rock characterized by a predominance of Plagioclase Feldspar In terms of elements, the crust is composed primarily of oxygen, silicon, magnesium, iron, calcium, and aluminium. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 WikipediaNaming Based on geophysical techniques, its thickness is estimated to be on average about 50 km. [1]

Partial melting within the mantle of the Moon gave rise to the eruption of mare basalts on the lunar surface. Analyses of these basalts indicate that the mantle is composed predominantly of the minerals olivine, orthopyroxene and clinopyroxene, and that the lunar mantle is more iron rich than that of the Earth. The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. Some lunar basalts contain high abundances of titanium (present in the mineral ilmenite), suggesting that the mantle is highly heterogeneous in composition. Titanium (taɪˈteɪniəm is a Chemical element with the symbol Ti and Atomic number 22 Ilmenite is a weakly magnetic titanium-iron oxide Mineral which is iron-black or steel-gray Moonquakes have been found to occur deep within the mantle of the Moon about 1,000 km below the surface. These occur with monthly periodicities and are related to tidal stresses caused by the eccentric orbit of the Moon about the Earth. [1]

The Moon has a mean density of 3,346. 4 kg/m³, making it the second densest moon in the Solar System after Io. TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek Nevertheless, several lines of evidence imply that the core of the Moon is small, with a radius of about 350 km or less. [1] This corresponds to only about 20% the size of the Moon, in contrast to about 50% as is the case for most other terrestrial bodies. The composition of the lunar core is not well constrained, but most believe that it is composed of metallic iron alloyed with a small amount of sulfur and nickel. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Analyses of the Moon's time-variable rotation indicate that the core is at least partly molten. [26]

### Topography

Topography of the Moon, referenced to the lunar geoid

The topography of the Moon has been measured by the methods of laser altimetry and stereo image analysis, most recently from data obtained during the Clementine mission. The Topography of the Moon has been measured by the methods of laser altimetry and stereo image analysis most recently from data obtained during the Clementine Topography ( topo-, "place" and graphia, "writing" is the study of Earth 's Surface features or those of Planets Spacecraft design The spacecraft was an octagonal prism 188 m high and 1 The most visible topographic feature is the giant far side South Pole-Aitken basin, which possesses the lowest elevations of the Moon. The South Pole-Aitken basin is an Impact crater on Earth 's Moon. The highest elevations are found just to the north-east of this basin, and it has been suggested that this area might represent thick ejecta deposits that were emplaced during an oblique South Pole-Aitken basin impact event. Other large impact basins, such as Imbrium, Serenitatis, Crisium, Smythii, and Orientale, also possess regionally low elevations and elevated rims. Mare Imbrium, Latin for "Sea of Showers" or "Sea of Rains" is a vast Lunar mare (mahr'-ay filling a basin on Earth 's Moon Mare Serenitatis (the "sea of serenity" is a Lunar mare that sits just to the east of Mare Imbrium on Earth's moon. Mare Crisium (the "sea of crises" is a Lunar mare located in the Moon 's Crisium basin just northeast of Mare Tranquillitatis. Mare Smythii ( Latin for "Sea of Smyth" is a Lunar mare located along the equator on the easternmost edge of the lunar near side Like a target ring bull's-eye the Lunar mare Mare Orientale (the "eastern sea" is one of the most striking large scale lunar features Another distinguishing feature of the Moon's shape is that the elevations are on average about 1. 9 km higher on the far side than the near side. [1]

### Gravity field

Main article: Gravity of the Moon

The gravitational field of the Moon has been determined through tracking of radio signals emitted by orbiting spacecraft. The gravitational field of the Moon has been determined by the tracking of radio signals emitted by orbiting spacecraft The principle used depends on the Doppler effect, whereby the spacecraft acceleration in the line-of-sight direction can be determined by means of small shifts in frequency of the radio signal, and the distance from the spacecraft to a station on Earth. The Doppler effect (or Doppler shift) named after Christian Doppler, is the change in Frequency and Wavelength of a Wave for However, because of the Moon's synchronous rotation it is not possible to track spacecraft much over the limbs of the Moon, and the farside gravity field is thus only poorly characterised. In Astronomy, synchronous rotation is a planetological term describing a body orbiting another where the orbiting body takes as long to rotate [27]

Radial gravitational anomaly at the surface of the Moon

The major characteristic of the Moon's gravitational field is the presence of mascons, which are large positive gravitational anomalies associated with some of the giant impact basins. Mass concentration can have different meaning in astronomy or chemistry In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body [28] These anomalies greatly influence the orbit of spacecraft about the Moon, and an accurate gravitational model is necessary in the planning of both manned and unmanned missions. The mascons are in part due to the presence of dense mare basaltic lava flows that fill some of the impact basins. However, lava flows by themselves can not explain the entirety of the gravitational signature, and uplift of the crust-mantle interface is required as well. Based on Lunar Prospector gravitational models, it has been suggested that some mascons exist that do not show evidence for mare basaltic volcanism. The Lunar Prospector mission was the third selected by NASA for full development and construction as part of the Discovery Program. [29] The huge expanse of mare basaltic volcanism associated with Oceanus Procellarum does not possess a positive gravitational anomaly. Oceanus Procellarum (oʊˈsiːənəs ˌprɒsəˈlɛərəm Latin for "Ocean of Storms" is a vast Lunar mare on the western edge of the near side of

### Magnetic field

Total magnetic field strength at the surface of the Moon as derived from the Lunar Prospector electron reflectometer experiment

The Moon has an external magnetic field of the order of one to a hundred nanotesla—less than one hundredth that of the Earth, which is 30-60 microtesla. The external Magnetic field of the Moon is very weak in comparison to that of the Earth The Lunar Prospector mission was the third selected by NASA for full development and construction as part of the Discovery Program. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges The tesla (symbol T) is the SI derived unit of Magnetic field B (which is also known as "magnetic flux density" and "magnetic Earth 's magnetic field (and the surface magnetic field) is approximately a Magnetic dipole, with one pole near the North pole (see Other major differences are that the Moon does not currently have a dipolar magnetic field (as would be generated by a geodynamo in its core), and the magnetizations that are present are almost entirely crustal in origin. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a The dynamo theory proposes a mechanism by which a celestial body such as the Earth generates a Magnetic field. [30] One hypothesis holds that the crustal magnetizations were acquired early in lunar history when a geodynamo was still operating. The small size of the lunar core, however, is a potential obstacle to this theory. Alternatively, it is possible that on an airless body such as the Moon, transient magnetic fields could be generated during large impact events. In support of this, it has been noted that the largest crustal magnetizations appear to be located near the antipodes of the giant impact basins. The antipodes refer to lands and peoples located on the opposite side of the World compared to the speaker It has been proposed that such a phenomenon could result from the free expansion of an impact generated plasma cloud around the Moon in the presence of an ambient magnetic field. [31]

### Surface Temperature

During the lunar day, the surface temperature averages 107°C, and during the lunar night, it averages -153°C. [35]

## Origin and geologic evolution

### Formation

Several mechanisms have been suggested for the Moon's formation. The formation of the Moon is believed to have occurred 4. 527 ± 0. 010 billion years ago, about 30–50 million years after the origin of the Solar System. [36]

Fission hypothesis
Early speculation proposed that the Moon broke off from the Earth's crust because of centrifugal forces, leaving a basin – presumed to be the Pacific Ocean – behind as a scar. The Pacific Ocean is the largest of the Earth 's Oceanic divisions [37] This idea, however, would require too great an initial spin of the Earth; and, even had this been possible, the process should have resulted in the Moon's orbit following Earth's equatorial plane. In Astronomy and Navigation, the celestial sphere is an imaginary rotating Sphere of "gigantic Radius " This is not the case.
Capture hypothesis
Other speculation has centered on the Moon being formed elsewhere and subsequently being captured by Earth's gravity. [38] However, the conditions believed necessary for such a mechanism to work, such as an extended atmosphere of the Earth in order to dissipate the energy of the passing Moon, are improbable. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five In Physics, dissipation embodies the concept of a Dynamical system where important mechanical modes such as Waves or Oscillations lose Energy
Co-formation hypothesis
The co-formation hypothesis proposes that the Earth and the Moon formed together at the same time and place from the primordial accretion disk. An accretion disc (or accretion disk) is a structure (often a Circumstellar disk) formed by diffuse material in orbital motion around a central body The Moon would have formed from material surrounding the proto-Earth, similar to the formation of the planets around the Sun. Some suggest that this hypothesis fails adequately to explain the depletion of metallic iron in the Moon.
A major deficiency in all these hypotheses is that they cannot readily account for the high angular momentum of the Earth–Moon system. In Physics, the angular momentum of a particle about an origin is a vector quantity equal to the mass of the particle multiplied by the Cross product of the position [39]
Giant Impact hypothesis
The prevailing hypothesis today is that the Earth–Moon system formed as a result of a giant impact. A Mars-sized body (labelled "Theia") is believed to have hit the proto-Earth, blasting sufficient material into orbit around the proto-Earth to form the Moon through accretion. [6] As accretion is the process by which all planetary bodies are believed to have formed, giant impacts are thought to have affected most if not all planets. Computer simulations modelling a giant impact are consistent with measurements of the angular momentum of the Earth–Moon system, as well as the small size of the lunar core. In Physics, the angular momentum of a particle about an origin is a vector quantity equal to the mass of the particle multiplied by the Cross product of the position [40] Unresolved questions regarding this theory concern the determination of the relative sizes of the proto-Earth and Theia and of how much material from these two bodies formed the Moon.

### Lunar magma ocean

As a result of the large amount of energy liberated during both the giant impact event and the subsequent reaccretion of material in Earth orbit, it is commonly believed that a large portion of the Moon was once initially molten. The molten outer portion of the Moon at this time is referred to as a magma ocean, and estimates for its depth range from about 500 km to the entire radius of the Moon. According to the Giant impact hypothesis a large amount of energy was liberated in the formation of the Moon and it is predicted that as a result a large portion of the Moon was once completely [12]

As the magma ocean cooled, it fractionally crystallised and differentiated, giving rise to a geochemically distinct crust and mantle. In Planetary science, planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical The mantle is inferred to have formed largely by the precipitation and sinking of the minerals olivine, clinopyroxene, and orthopyroxene. The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. After about three-quarters of magma ocean crystallisation was complete, the mineral anorthite is inferred to have precipitated and floated to the surface because of its low density, forming the crust. Anorthite is a compositional variety of Plagioclase Feldspar. [12]

The final liquids to crystallise from the magma ocean would have been initially sandwiched between the crust and mantle, and would have contained a high abundance of incompatible and heat-producing elements. This geochemical component is referred to by the acronym KREEP, for potassium (K), rare earth elements (REE), and phosphorus (P), and appears to be concentrated within the Procellarum KREEP Terrane, which is a small geologic province that encompasses most of Oceanus Procellarum and Mare Imbrium on the near side of the Moon. KREEP, an Acronym built from the letters K (the atomic symbol for the element Potassium) REE ( '''R'''are '''E'''arth Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 The Moon is composed of two major geologic provinces that have a unique origin composition and thermal evolution Oceanus Procellarum (oʊˈsiːənəs ˌprɒsəˈlɛərəm Latin for "Ocean of Storms" is a vast Lunar mare on the western edge of the near side of Mare Imbrium, Latin for "Sea of Showers" or "Sea of Rains" is a vast Lunar mare (mahr'-ay filling a basin on Earth 's Moon [1]

### Geologic evolution

A large portion of the Moon's post–magma-ocean geologic evolution was dominated by impact cratering. The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar The lunar geologic timescale is largely divided in time on the basis of prominent basin-forming impact events, such as Nectaris, Imbrium, and Orientale. The lunar geologic timescale (or selenologic timescale) divides the history of Earth 's moon into five generally recognized geologic periods the Copernican The Nectarian Period of the Lunar geologic timescale runs from 3920 million years ago to 3850 million years ago In the Lunar geologic timescale, the Lower Imbrian epoch occurred between 3850 million years ago to about 3800 million years ago Like a target ring bull's-eye the Lunar mare Mare Orientale (the "eastern sea" is one of the most striking large scale lunar features These impact structures are characterised by multiple rings of uplifted material, and are typically hundreds to thousands of kilometres in diameter. Each multi-ring basin is associated with a broad apron of ejecta deposits that forms a regional stratigraphic horizon. While only a few multi-ring basins have been definitively dated, they are useful for assigning relative ages on the basis of stratigraphic grounds. Stratigraphy, a branch of Geology, studies rock layers and layering ( stratification) The continuous effects of impact cratering are responsible for forming the regolith. Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock.

The other major geologic process that affected the Moon's surface was mare volcanism. The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions The enhancement of heat-producing elements within the Procellarum KREEP Terrane is thought to have caused the underlying mantle to heat up, and eventually, to partially melt. The Moon is composed of two major geologic provinces that have a unique origin composition and thermal evolution A portion of these magmas rose to the surface and erupted, accounting for the high concentration of mare basalts on the near side of the Moon. [12] Most of the Moon's mare basalts erupted during the Imbrian period in this geologic province 3. The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions 0–3. 5 billion years ago. Nevertheless, some dated samples are as old as 4. 2 billion years,[41] and the youngest eruptions, based on the method of crater counting, are believed to have occurred only 1. Crater counting refers to a method for estimating the age of a planet's surface 2 billion years ago. [42]

There has been controversy over whether features on the Moon's surface undergo changes over time. Some observers have claimed that craters either appeared or disappeared, or that other forms of transient phenomena had occurred. Today, many of these claims are thought to be illusory, resulting from observation under different lighting conditions, poor astronomical seeing, or the inadequacy of earlier drawings. Astronomical seeing refers to the blurring and twinkling of astronomical objects such as stars caused by Turbulence in the Earth's atmosphere Nevertheless, it is known that the phenomenon of outgassing does occasionally occur, and these events could be responsible for a minor percentage of the reported lunar transient phenomena. Outgassing (sometimes called offgassing, particularly when in reference to indoor Air quality is the slow release of a Gas that was trapped A transient lunar phenomenon ( TLP) or "Lunar Transient Phenomena" (LTP refers to short-lived lights colors or changes in appearance of the lunar surface Recently, it has been suggested that a roughly 3 km diameter region of the lunar surface was modified by a gas release event about a million years ago. [43][44]

### Moon rocks

Main article: Moon rocks

Moon rocks fall into two main categories, based on whether they underlie the lunar highlands (terrae) or the maria. Moon Rock is the debut Album by Paul Steel. It was cancelled for release after the album's first single Your Loss failed to chart upon The lunar highlands rocks are composed of three suites: the ferroan anorthosite suite, the magnesian suite, and the alkali suite (some consider the alkali suite to be a subset of the mg-suite). The ferroan anorthosite suite rocks are composed almost exclusively of the mineral anorthite (a calic plagioclase feldspar), and are believed to represent plagioclase flotation cumulates of the lunar magma ocean. Anorthite is a compositional variety of Plagioclase Feldspar. Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family The ferroan anorthosites have been dated using radiometric methods to have formed about 4. 4 billion years ago. [41][42]

The mg- and alkali-suite rocks are predominantly mafic plutonic rocks. Typical rocks are dunites, troctolites, gabbros, alkali anorthosites, and more rarely, granite. Dunite (ˈduːnaɪt or /ˈdʌnaɪt/ is an igneous, Plutonic rock, of Ultramafic composition with coarse-grained or Phaneritic Troctolite is a rare Ultramafic Intrusive rock type It consists essentially of variable amounts of Olivine and calcic Plagioclase along with Gabbro (ˈɡæbrəʊ is a dark coarse-grained intrusive Igneous rock chemically equivalent to Basalt. Anorthosite (æˈnɔrθəsaɪt/ /ə- is a Phaneritic, Intrusive Igneous rock characterized by a predominance of Plagioclase Feldspar Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. In contrast to the ferroan anorthosite suite, these rocks all have relatively high Mg/Fe ratios in their mafic minerals. In general, these rocks represent intrusions into the already-formed highlands crust (though a few rare samples appear to represent extrusive lavas), and they have been dated to have formed about 4. 4–3. 9 billion years ago. Many of these rocks have high abundances of, or are genetically related to, the geochemical component KREEP. KREEP, an Acronym built from the letters K (the atomic symbol for the element Potassium) REE ( '''R'''are '''E'''arth

The lunar maria consist entirely of mare basalts. While similar to terrestrial basalts, they have much higher abundances of iron, are completely lacking in hydrous alteration products, and have a large range of titanium abundances. [45][46]

Astronauts have reported that the dust from the surface felt like snow and smelled like spent gunpowder. Gunpowder is a an explosive mixture of Sulfur, Charcoal and Potassium nitrate (also known as saltpetre/saltpeter that burns rapidly producing volumes [47] The dust is mostly made of silicon dioxide glass (SiO2), most likely created from the meteors that have crashed into the Moon's surface. The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide It also contains calcium and magnesium. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24

## Orbit and relationship to Earth

Main article: Orbit of the Moon
Earth as viewed from the Moon during the Apollo 8 mission, Christmas Eve, 1968

The Moon makes a complete orbit around the Earth with respect to the fixed stars (its sidereal period) about once every 27. The orbit of the Moon around the Earth is completed in approximately 27 EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Christmas Eve, December 24, is the day before Christmas Day, the celebrated birthday of Jesus. The orbital period is the time taken for a given object to make one complete Orbit about another object 3 days. However, since the Earth is moving in its orbit about the Sun at the same time, it takes slightly longer for the Moon to show its same phase to Earth, which is about 29. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth 5 days (its synodic period). The orbital period is the time taken for a given object to make one complete Orbit about another object [6] Unlike most satellites of other planets, the Moon orbits near the ecliptic and not the Earth's equatorial plane. The ecliptic is the apparent path that the Sun traces out in the sky during the year In Astronomy and Navigation, the celestial sphere is an imaginary rotating Sphere of "gigantic Radius " It is the largest moon in the solar system relative to the size of its planet. (Charon is larger relative to the dwarf planet Pluto. Charon (ˈʃærən; also, as in Χάρων) discovered in 1978 is either the largest Moon of Pluto or the smaller member of a double A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded ) The natural satellites orbiting other planets are called "moons", after Earth's Moon. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary.

Most of the tidal effects seen on the Earth are caused by the Moon's gravitational pull, with the Sun making only a small contribution. Tidal effects result in an increase of the mean Earth-Moon distance of about 3. 8 m per century, or 3. 8 cm per year. [48] As a result of the conservation of angular momentum, the increasing semimajor axis of the Moon is accompanied by a gradual slowing of the Earth's rotation by about 0. In Physics, the angular momentum of a particle about an origin is a vector quantity equal to the mass of the particle multiplied by the Cross product of the position 002 seconds per day per century. [49]

The Earth–Moon system is sometimes considered to be a double planet rather than a planet–moon system. " Double planet " is an informal term used to describe a Planet with a moon that may be large enough to be considered a planet in its own right a common definition This is due to the exceptionally large size of the Moon relative to its host planet; the Moon is a quarter the diameter of Earth and 1/81 its mass. However, this definition is criticised by some, since the common centre of mass of the system (the barycentre) is located about 1,700 km beneath the surface of the Earth, or about a quarter of the Earth's radius. The surface of the Moon is less than 1/10th that of the Earth, and only about a quarter the size of the Earth's land area (or about as large as Russia, Canada, and the U. S. combined).

In 1997, the asteroid 3753 Cruithne was found to have an unusual Earth-associated horseshoe orbit. TemplateInfobox Planet. --> 3753 Cruithne (ˈkrɪnjə from Old Irish ˈkrɪθnɛ Modern A horseshoe Orbit appears when a viewer on an orbiting body (like Earth watches the movement of another orbiting body whose orbit is skinnier (more eccentric but has about However, astronomers do not consider it to be a second moon of Earth, and its orbit is not stable in the long term. [50] Three other near-Earth asteroids, (54509) 2000 PH5, (85770) 1998 UP1 and 2002 AA29, which exist in orbits similar to Cruithne's, have since been discovered. Near-Earth asteroids (NEAs are Asteroids whose Orbits are close to Earth 's orbit TemplateInfobox Planet. -->Asteroid ( also written 2002 AA29) is a Near-Earth asteroid [51]

The relative sizes and separation of the Earth–Moon system are shown to scale above. The beam of light is depicted travelling between the Earth and the Moon in the same time it actually takes light to scale the real distance between them: 1. 255 seconds at its mean orbital distance. The light beam helps provide the sense of scale of the Earth-Moon system relative to the Sun, which is 8. 28 light-minutes away (photosphere to Earth surface).

## Ocean tides

Earth’s ocean tides are initiated by the tidal force (a gradient in intensity) of Moon’s gravity and are magnified by a host of effects in Earth’s oceans. Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood The tidal force is a secondary effect of the Force of Gravity and is responsible for the Tides It arises because the gravitational acceleration experienced The gravitational tidal force arises because the side of Earth facing the Moon (nearest it) is attracted more strongly by the Moon’s gravity than is the center of the Earth and—even less so—the Earth’s far side. The gravitational tide stretches the Earth’s oceans into an ellipse with the Earth in the center. The effect takes the form of two bulges—elevated sea level relative to the Earth; one nearest the Moon and one farthest from it. Since these two bulges rotate around the Earth once a day as it spins on its axis, ocean water is continuously rushing towards the ever-moving bulges. The effects of the two bulges and the massive ocean currents chasing them are magnified by an interplay of other effects; namely frictional coupling of water to Earth’s rotation through the ocean floors, inertia of water’s movement, ocean basins that get shallower near land, and oscillations between different ocean basins. The magnifying effect is a bit like water sloshing high up the sloped end of a bathtub after a relatively small disturbance of one’s body in the deep part of the tub.

Gravitational coupling between the Moon and the ocean bulge nearest the Moon affects its orbit. The Earth rotates on its axis in the very same direction, and roughly 27 times faster, than the Moon orbits the Earth. Thus, frictional coupling between the sea floors and ocean waters, as well as water’s inertia, drags the peak of the near-Moon tidal bulge slightly forward of the imaginary line connecting the centers of the Earth and Moon. The vis insita or innate force of matter is a power of resisting by which every body as much as in it lies endeavors to preserve in its present state whether it be of rest or of moving From the Moon’s perspective, the center of mass of the near-Moon tidal bulge is perpetually slightly ahead of the point about which it is orbiting. Precisely the opposite effect occurs with the bulge farthest from the Moon; it lags behind the imaginary line. However it is 12,756 km farther away and has slightly less gravitational coupling to the Moon. Consequently, the Moon is constantly being gravitationally attracted forward in its orbit about the Earth. This gravitational coupling drains kinetic energy and angular momentum from the Earth’s rotation (see also, Day and Leap second). The kinetic energy of an object is the extra Energy which it possesses due to its motion In Physics, the angular momentum of a particle about an origin is a vector quantity equal to the mass of the particle multiplied by the Cross product of the position A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the A leap second is a one- Second adjustment that keeps broadcast standards for time of day close to mean solar time. In turn, angular momentum is added to the Moon’s orbit, which lifts the Moon into a higher orbit with a longer period. The orbit of the Moon around the Earth is completed in approximately 27 The effect on the Moon’s orbital radius is a small one, just 0. 10 ppb/year, but results in a measurable 3. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly 82 cm annual increase in the Earth-Moon distance. [52] Cumulatively, this effect becomes ever more significant over time; since when astronauts first landed on the Moon approximately 39 years ago, it is now 1. 49 metres farther away.

## Eclipses

Main articles: Solar eclipse and Lunar eclipse
The 1999 solar eclipse
The 3 March 2007 lunar eclipse

Eclipses can occur only when the Sun, Earth, and Moon are all in a straight line. A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured A lunar eclipse occurs whenever the Moon passes through some portion of the Earth's shadow A lunar eclipse occurs whenever the Moon passes through some portion of the Earth's shadow Solar eclipses occur near a new moon, when the Moon is between the Sun and Earth. A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured This article is about the lunar phase for other uses see New Moon (disambiguation. In contrast, lunar eclipses occur near a full moon, when the Earth is between the Sun and Moon. A lunar eclipse occurs whenever the Moon passes through some portion of the Earth's shadow Full moon is a Lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun.

Because the Moon's orbit around the Earth is inclined by about 5° with respect to the orbit of the Earth around the Sun, eclipses do not occur at every full and new moon. The ecliptic is the apparent path that the Sun traces out in the sky during the year For an eclipse to occur, the Moon must be near the intersection of the two orbital planes. [53]

The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by the Earth, is described by the saros cycle, which has a period of approximately 6,585. The Saros cycle is an Eclipse cycle with a period of about 18 years 11 days 8 hours (approximately 6585⅓ days that can be used to predict Eclipses of the Sun 3 days (18 years 11 days 8 hours). [54]

The angular diameters of the Moon and the Sun as seen from Earth overlap in their variation, so that both total and annular solar eclipses are possible. An eclipse is an astronomical event that occurs when one Celestial object moves into the shadow of another A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured [55] In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye. A corona is a type of plasma " atmosphere " of the Sun or other celestial body extending millions of Kilometres into space most easily The naked eye is a Figure of speech referring to human Visual perception that is unaided by enhancing equipment such as a Telescope or Since the distance between the Moon and the Earth is very slightly increasing over time, the angular diameter of the Moon is decreasing. This means that hundreds of millions of years ago the Moon could always completely cover the Sun on solar eclipses so that no annular eclipses were possible. Likewise, about 600 million years from now (assuming that the angular diameter of the Sun will not change), the Moon will no longer cover the Sun completely and only annular eclipses will occur. [53]

A phenomenon related to eclipse is occultation. In Shia Islam The Occultation is a term used to designate the hidden state of the Imam of the Time. The Moon is continuously blocking our view of the sky by a 1/2 degree-wide circular area. When a bright star or planet passes behind the Moon it is occulted or hidden from view. A solar eclipse is an occultation of the Sun. Because the Moon is close to Earth, occultations of individual stars are not visible everywhere, nor at the same time. Because of the precession of the lunar orbit, each year different stars are occulted. [56]

The most recent lunar eclipse was on February 20, 2008. Events 1472 - Orkney and Shetland are left by Norway to Scotland, due to a Dowry payment 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common It was a total eclipse. The entire event was visible from South America and most of North America (on Feb. 20), as well as Western Europe, Africa, and western Asia (on Feb. 21). The most recent solar eclipse took place on September 11, 2007, visible from southern South America and parts of Antarctica. Events 9 - The Battle of the Teutoburg Forest ends 506 - The Bishops of Visigothic Gaul Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. The next total solar eclipse, on August 1, 2008, will have a path of totality beginning in northern Canada and passing through Russia and China. Events 30 BC - Octavian (later known as Augustus enters Alexandria, Egypt, bringing it under the control of the Roman 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common [57]

## Observation

During its brightest phase, at "full moon", the Moon has an apparent magnitude of about −12. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth The phenomenon known as planetshine occurs when reflected Sunlight from a Planet illuminates the dark side of one of its moons Typically this The Moon is Earth 's largest Natural satellite and the nearest major celestial object The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 6. By comparison, the Sun has an apparent magnitude of −26. 8. When the Moon is in a quarter phase, its brightness is not half of a full moon, but only about a tenth. This is because the lunar surface is not a perfect Lambertian reflector. See also Lambert's cosine law If a surface exhibits Lambertian reflectance, light falling on it is scattered such that the apparent brightness of the surface to an observer When the Moon is full the opposition effect makes it appear brighter, but away from full there are shadows projected onto the surface which diminish the amount of reflected light. The opposition effect (also opposition spike, or opposition surge) is the brightening of a rough surface or an object with many particles when illuminated from directly

The Moon appears larger when close to the horizon. This is a purely psychological effect (see Moon illusion). The Moon illusion is an Optical illusion in which the Moon appears larger near the Horizon than it does while higher up in the Sky. It is actually about 1. 5% smaller when the Moon is near the horizon than when it is high in the sky (because it is farther away by up to one Earth radius).

The moon appears as a relatively bright object in the sky, in spite of its low albedo. The albedo of an object is the extent to which it diffusely reflects light from the sun The Moon is about the poorest reflector in the solar system and reflects only about 7% of the light incident upon it (about the same proportion as is reflected by a lump of coal). The Solar System consists of the Sun and those celestial objects bound to it by Gravity. [58] Color constancy in the visual system recalibrates the relations between the colours of an object and its surroundings, and since the surrounding sky is comparatively dark the sunlit Moon is perceived as a bright object. Color constancy is an example of Subjective constancy and a feature of the human Color perception system which ensures that the perceived color of objects remains The visual system is the part of the Nervous system which allows organisms to see.

A halo around the Moon

The highest altitude of the Moon on a day varies and has nearly the same limits as the Sun. A halo (ἅλως also known as a nimbus, icebow or Gloriole) is an Optical phenomenon that appears near or around the Sun or In Astronomy, a celestial coordinate system is a Coordinate system for mapping positions in the sky It also depends on the Earth season and lunar phase, with the full moon being highest in winter. Moreover, the 18. 6 year nodes cycle also has an influence, as when the ascending node of the lunar orbit is in the vernal equinox, the lunar declination can go as far as 28° each month (which happened most recently in 2006). This results that the Moon can go overhead on latitudes till 28 degrees (e. g. Florida, Canary Islands or in the southern hemisphere Brisbane). Florida ( is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the The Canary Islands ( English pronunciation kəˈnæriː ˈaɪləndz Spanish: Islas Canarias, ˈizlas kaˈnarjas are a Spanish Brisbane ( is the state capital of Queensland. Brisbane is the third most populous city in Australia and the most populous city of Queensland Slightly more than 9 years later (next time in 2015) the declination reaches only 18° N or S each month. The orientation of the Moon's crescent also depends on the latitude of the observation site. Close to the equator, an observer can see a boat Moon. [59]

Like the Sun, the Moon can give rise to atmospheric effects, including a 22° halo ring, and the smaller coronal rings seen more often through thin clouds. A halo (ἅλως also known as a nimbus, icebow or Gloriole) is an Optical phenomenon that appears near or around the Sun or In Meteorology, a corona is produced by the Diffraction of light from either the Sun or the Moon by individual small water droplets (and sometimes For more information on how the Moon appears in Earth's sky, see lunar phase. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth

## Exploration

Main articles: Exploration of the Moon, Apollo program, and Moon landing
See also: Robotic exploration of the Moon, Future lunar missions, and Colonization of the Moon

The first leap in lunar observation was prompted by the invention of the telescope. The physical exploration of the Moon began when Luna 2, a Space probe launched by the Soviet Union, impacted the surface of the Moon on A moon landing is the arrival of an intact manned or unmanned Spacecraft on the surface of a Planet 's Natural satellite. See also Exploration of the Moon Future lunar missions|Project Apollo Pioneer program Pioneer 0 (USA 1958 – failure – orbiter Currently there are several future lunar missions scheduled by various nations and organisations The colonization of the Moon is the proposed establishment of permanent human communities on the Moon. Galileo Galilei made good use of this new instrument and observed mountains and craters on the Moon's surface. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher

The Cold War-inspired space race between the Soviet Union and the U. Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the The Space Race was a competition of space exploration between the Soviet Union and the United States, which lasted roughly from 1957 to 1975 S. led to an acceleration of interest in the Moon. Unmanned probes, both flyby and impact/lander missions, were sent almost as soon as launcher capabilities would allow. The Soviet Union's Luna program was the first to reach the Moon with unmanned spacecraft. The Luna programme (from the Russian word "Luna" meaning "Moon" occasionally called Lunik or Lunnik, was a series of Robotic spacecraft A spacecraft is a Vehicle or machine designed for Spaceflight. The first man-made object to escape Earth's gravity and pass near the Moon was Luna 1, the first man-made object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. Luna 1 (E-1 series also known as Mechta (Мечта lit: Dream) was the first Spacecraft to reach the vicinity Luna 2 (E-1A series was the second of the Soviet Union's Luna program spacecraft launched in the direction of the Moon. The Soviet spaceprobe Luna 3 (E-3 series was the third spacecraft sent successfully to the Moon and was an early triumph in the human exploration of outer space The first spacecraft to perform a successful lunar soft landing was Luna 9 and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966. Sources [6] Moon samples have been brought back to Earth by three Luna missions (Luna 16, 20, and 24) and the Apollo missions 11 to 17 (except Apollo 13, which aborted its planned lunar landing). Mission profile The Luna 16 automatic station was launched toward the Moon from a preliminary Earth orbit and after one mid-course correction on 13 September it entered Luna 20 (Ye-8-5 series was an Unmanned space mission of the Luna program, also called Lunik 20

The landing of the first humans on the Moon in 1969 is seen as the culmination of the space race. [60] 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. Neil Alden Armstrong (born August 5 1930 is a former American Astronaut, Test pilot, University Professor, and United States Events 356 BC - Herostratus sets fire to the Temple of Artemis in Ephesus, one of the Seven Wonders of the World Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. The American Moon landing and return was enabled by considerable technological advances, in domains such as ablation chemistry and atmospheric re-entry technology, in the early 1960s. A moon landing is the arrival of an intact manned or unmanned Spacecraft on the surface of a Planet 's Natural satellite. Ablation is defined as the removal of material from the surface of an object by Vaporization, Chipping, or other erosive processes

Scientific instrument packages were installed on the lunar surface during all of the Apollo missions. Long-lived ALSEP stations (Apollo lunar surface experiment package) were installed at the Apollo 12, 14, 15, 16, and 17 landing sites, whereas a temporary station referred to as EASEP (Early Apollo Scientific Experiments Package) was installed during the Apollo 11 mission. The ALSEP stations contained, among others, heat flow probes, seismometers, magnetometers, and corner-cube retroreflectors. Transmission of data to Earth was terminated on 30 September 1977 because of budgetary considerations. Events 1399 - Henry IV is proclaimed King of England. 1744 - France and Spain defeat the Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays [61][62] Since the lunar laser ranging (LLR) corner-cube arrays are passive instruments, they are still being used. The ongoing Lunar Laser Ranging Experiment measures the distance between the Earth and the Moon using laser ranging. Ranging to the LLR stations is routinely performed from earth-based stations with an accuracy of a few centimetres, and data from this experiment are being used to place constraints on the size of the lunar core. [63]

35 years, 180 days have now passed since Eugene Cernan, as part of the mission Apollo 17, left the surface of the Moon on 14 December 1972 and no one has set foot on it since. Eugene Andrew Cernan (born March 14, 1934) is a retired United States Navy officer and a former NASA Astronaut of Czechoslovakian Events 1287 - St Lucia's flood: The Zuider Zee sea wall in the Netherlands collapses killing over 50000 people Year 1972 ( MCMLXXII) was a Leap year starting on Saturday (link will display full calendar of the Gregorian calendar.

Astronaut Buzz Aldrin photographed by Neil Armstrong during the first moon landing on 20 July 1969. An astronaut or cosmonaut (космона́вт) is a person trained Buzz Aldrin (born Edwin Eugene Aldrin Jr, January 20, 1930 in Glen Ridge, New Jersey) is an American Aviator Neil Alden Armstrong (born August 5 1930 is a former American Astronaut, Test pilot, University Professor, and United States A moon landing is the arrival of an intact manned or unmanned Spacecraft on the surface of a Planet 's Natural satellite. Events 1304 - Wars of Scottish Independence: Fall of Stirling Castle - King Edward I of England takes the last rebel stronghold Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar.

From the mid-1960s to the mid-1970s, there were 65 instances of artificial objects reaching the Moon (both manned and robotic, with ten in 1971 alone), with the last being Luna 24 in 1976. Only 18 of these were controlled moon landings, with nine completing a round trip from Earth and returning samples of moon rocks. A moon landing is the arrival of an intact manned or unmanned Spacecraft on the surface of a Planet 's Natural satellite. Moon Rock is the debut Album by Paul Steel. It was cancelled for release after the album's first single Your Loss failed to chart upon The Soviet Union then turned its primary attention to Venus and space stations, and the U. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University A space station is an artificial structure designed for Humans to live in Outer space. S. to Mars and beyond. In 1990, Japan orbited the Moon with the Hiten spacecraft, becoming the third country to place a spacecraft into lunar orbit. The Hiten (Japanese "flying angel" Spacecraft (known before launch as Muses-A built by the Institute of Space and Astronautical Science of Japan The spacecraft released a smaller probe, Hagormo, in lunar orbit, but the transmitter failed, thereby preventing further scientific use of the mission.

In 1994, the U. S. finally returned to the Moon, robotically at least, sending the Joint Defense Department/NASA spacecraft Clementine. Spacecraft design The spacecraft was an octagonal prism 188 m high and 1 This mission obtained the first near-global topographic map of the Moon, and the first global multispectral images of the lunar surface. Multi-spectral imaging is a technology originally developed for space-based imaging This was followed by the Lunar Prospector mission in 1998. The Lunar Prospector mission was the third selected by NASA for full development and construction as part of the Discovery Program. The neutron spectrometer on Lunar Prospector 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 metres of the regolith within permanently shadowed craters. This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. A spectrometer is an Optical instrument used to measure properties of Light over a specific portion of the Electromagnetic spectrum, typically used The European spacecraft Smart 1 was launched September 27, 2003 and was in lunar orbit from November 15, 2004 to September 3, 2006. SMART-1 was a Swedish -designed European Space Agency Satellite that Orbited around the Moon. Events 489 - Odoacer attacks Theodoric at the Battle of Verona and is defeated again Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Events 36 BC - In the Battle of Naulochus, Marcus Vipsanius Agrippa, Admiral of Octavian, defeats Sextus Pompeius Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar.

On January 14, 2004, U. Events 1129 - Formal approval of the Order of the Templar at the Council of Troyes. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " S. President George W. Bush called for a plan to return manned missions to the Moon by 2020 (see Vision for Space Exploration). George Walker Bush ( born July 6 1946 is the forty-third and current President of the United States. The Vision for Space Exploration is the United States space policy announced on January 14, 2004 by U [64] NASA is now planning for the construction of a permanent outpost at one of the lunar poles. [65] The People's Republic of China has expressed ambitious plans for exploring the Moon and has started the Chang'e program for lunar exploration, successfully launching its first spacecraft, Chang'e-1, on October 24, 2007. Chinese Lunar Exploration Program ( CLEP) ( is a program of robotic explorations and human missions to the Moon undertaken by China National Space Administration Chang’e 1 ( an un-manned lunar orbiting Spacecraft, is part of the first phase of the Chinese Lunar Exploration Program. Events 69 - Second Battle of Bedriacum, forces under Antonius Primus the commander of the Danube armies loyal to Vespasian, defeat [66] India intends to launch several unmanned missions, beginning with Chandrayaan I in February 2008, followed by Chandrayaan II in 2010 or 2011; the latter is slated to include a robotic lunar rover. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country Chandrayaan I (चंद्रयान-1 lit Lunar Craft is an unmanned Lunar exploration mission by the Indian Space Research Organization (ISRO. India also has expressed its hope for a manned mission to the Moon by 2030. [67] The U. S. will launch the Lunar Reconnaissance Orbiter in 2008. The Lunar Precursor Robotic Program ( LPRP) is a program of Robotic spacecraft missions which NASA will use to prepare for future Human spaceflight Russia also announced to resume its previously frozen project Luna-Glob, consisting of an unmanned lander and orbiter, which is slated to land in 2012. Luna-Glob is an unmanned mission to the Moon planned by Russia including an orbiter as well as a landing module with 12 ground penetrating sensors [68]

The Google Lunar X Prize, announced 13 September 2007, hopes to boost and encourage privately funded lunar exploration. The Google Lunar X PRIZE, sometimes referred to as simply Moon 2 Events 509 BC - The Temple of Jupiter on Rome 's Capitoline Hill is dedicated on the ides of September Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. The X Prize Foundation is offering anyone 20 million dollars US who can land a robotic rover on the Moon and meet other specified criteria. The X PRIZE Foundation is a non-profit prize institute that designs and manages public competitions for the benefit of humanity

On September 14, 2007 the Japan Aerospace Exploration Agency launched SELENE, also known as Kaguya, a lunar orbiter which is fitted with a high-definition camera and two small satellites. Events 81 - Domitian becomes Emperor of the Roman Empire upon the death of his brother Titus. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. The, or JAXA, is Japan's national Aerospace agency JAXA was formed on October 1 2003 as an Independent Administrative Institution through the In Greek mythology, Selene (Σελήνη " Moon " English sɛˈliːniː was an archaic Lunar deity and the daughter of the Titans High-definition (HD video generally refers to any video system of higher resolution than standard-definition (SD video most commonly at display resolutions of 1280×720 The mission is expected to last one year. [69]

## Human understanding

See also: The Moon in mythology, Moon in art and literature, Lunar effect, and Artemis
Map of the Moon by Johannes Hevelius (1647)

The Moon has been the subject of many works of art and literature and the inspiration for countless others. The Moon has figured in many mythologies often paired or contrasted with the Sun. The Moon has been the subject of many works of art and literature and the inspiration for countless others The lunar effect is a Theory which overlaps into Sociology, Psychology and Physiology suggesting that there is correlation between specific In Greek mythology, Artemis language|Greek] ( Nominative), ( Genitive))] was the daughter of Zeus and Leto, and the twin sister Johannes Hevelius ( Latin) also called Johannes Hewel Johann Hewelke Johannes Höwelcke in German, or Jan Heweliusz (in Polish) It is a motif in the visual arts, the performing arts, poetry, prose and music. A 5,000-year-old rock carving at Knowth, Ireland may represent the Moon, which would be the earliest depiction discovered. Knowth (Cnobha is the site of a Neolithic Passage grave, one of the ancient monuments of the Brú na Bóinne complex in the valley Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world [70] In many prehistoric and ancient cultures, the Moon was thought to be a deity or other supernatural phenomenon, and astrological views of the Moon continue to be propagated today. In Mythology, a lunar deity is a God or Goddess associated with or symbolizing the moon see Moon (mythology. The term supernatural or supranatural ( Latin: super, supra "above" + natura "nature" pertains to entities events The Moon is the earth's companion satellite though some astronomers believe that it approaches being a planet in its own right

Among the first in the Western world to offer a scientific explanation for the Moon was the Greek philosopher Anaxagoras (d. The term ancient Greece refers to the period of Greek history lasting from the Greek Dark Ages ca Anaxagoras ( Greek: Ἀναξαγόρας c 500 BC &ndash 428 BC was a Pre-Socratic Greek philosopher famous for introducing the Cosmological 428 BC), who reasoned that the Sun and Moon were both giant spherical rocks, and that the latter reflected the light of the former. His atheistic view of the heavens was one cause for his imprisonment and eventual exile. [71]

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. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. This separation was held to be part of physics for many centuries after. [72]

Moon against the Belt of Venus

During the Warring States of China, astronomer Shi Shen (fl. The Belt of Venus or Venus's Girdle is the Victorian era name for an Atmospheric phenomenon seen at Sunrise and Sunset. The Warring States Period ( also known as the Era of Warring States covers the period from some time in the 5th century BC to the unification of China by the China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Shi Shen ( fl 4th century BC) was a Chinese Astronomer and contemporary of Gan De born in the State of Wei, also known as the 4th century BC) gave instructions for predicting solar eclipse and lunar eclipse based on the relative positions of the moon and sun. [73] Although the Chinese of the Han Dynasty (202 BC–202 AD) 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 (mentioned by Anaxagoras above). The Han Dynasty ( 206 BC–220 AD followed the Qin Dynasty and preceded the Three Kingdoms in China. In traditional Chinese culture, qi (zh [[wikt氣 氣]] Pinyin qì, Wade-Giles ch'i Jyutping [74] This was supported by mainstream thinkers such as Jing Fang (78–37 BC) and Zhang Heng (78–139 AD), but it was also opposed by the influential philosopher Wang Chong (27–97 AD). Jing Fang ( 78&ndash37 BC born Li Fang (李房 Courtesy name Junming (君明 was a Chinese music theorist, Mathematician Zhang Heng ( (CE 78–139 was an astronomer, mathematician, inventor, geographer, cartographer, artist, poet Wang Chong ( 27&ndashc 100 AD Wang also accurately described the process of the Water cycle. [74] Jing Fang noted the sphericity of the moon, while Zhang Heng accurately described lunar eclipse and solar eclipse. [74][75] These assertions were supported by Shen Kuo (1031–1095) of the Song Dynasty (960–1279) who 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. Shen Kuo or Shen Kua ( (1031&ndash1095 style name Cunzhong and pseudonym Mengqi Weng, was a Polymathic Chinese The Song Dynasty ( Wade-Giles: Sung Ch'ao was a ruling dynasty in China between 960&ndash1279 CE it succeeded the Five Dynasties and Ten Kingdoms [76] He also noted that the reason for the sun and moon not eclipsing every time their paths met was because of a small obliquity in their orbital paths. [76]

By the Middle Ages, before the invention of the telescope, more and more people began to recognise the Moon as a sphere, though they believed that it was "perfectly smooth". [77] In 1609, Galileo Galilei drew one of the first telescopic drawings of the Moon in his book Sidereus Nuncius and noted that it was not smooth but had mountains and craters. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher Sidereus Nuncius (usually translated into English as Sidereal Messenger, although Starry Messenger and Sidereal Message are Later in the 17th century, Giovanni Battista Riccioli and Francesco Maria Grimaldi drew a map of the Moon and gave many craters the names they still have today. Giovanni Battista Riccioli ( April 17 1598 – June 25 1671) was an Italian Astronomer. Francesco Maria Grimaldi ( April 2, 1618 - December 28, 1663) was an Italian Mathematician and Physicist who

Still from silent film Le Voyage dans la Lune (1902) by Georges Méliès

On maps, the dark parts of the Moon's surface were called maria (singular mare) or seas, and the light parts were called terrae or continents. A Trip to the Moon (French fr Le Voyage dans la lune) is a 1902 French Black and white silent Science fiction Georges Méliès ( December 8, 1861 &ndash January 21, 1938) full name Marie-Georges-Jean Méliès, was a French The possibility that the Moon contains vegetation and is inhabited by selenites was seriously considered by major astronomers even into the first decades of the 19th century. The contrast between the brighter highlands and darker maria create the patterns seen by different cultures as the Man in the Moon, the rabbit and the buffalo, among others. The Man in the Moon is an imaginary figure resembling a human face head or body that observers from some cultural backgrounds typically perceive in the bright disc of the full

In 1835, the Great Moon Hoax fooled some people into thinking that there were exotic animals living on the Moon. " The Great Moon Hoax " was a series of six articles that were published in the New York Sun beginning on August 25, 1835 about [78] Almost at the same time however (during 1834–1836), Wilhelm Beer and Johann Heinrich Mädler were publishing their four-volume Mappa Selenographica and the book Der Mond in 1837, which firmly established the conclusion that the Moon has no bodies of water nor any appreciable atmosphere. Wilhelm Wolff Beer ( 4 January 1797 &ndash 27 March 1850) was a Banker and Astronomer from Berlin, Johann Heinrich von Mädler ( May 29 1794 &ndash March 14 1874) was a German Astronomer.

The far side of the Moon remained completely unknown until the Luna 3 probe was launched in 1959, and was extensively mapped by the Lunar Orbiter program in the 1960s. The Soviet spaceprobe Luna 3 (E-3 series was the third spacecraft sent successfully to the Moon and was an early triumph in the human exploration of outer space The Lunar Orbiter program was a series of five unmanned Lunar orbiter missions launched by the United States in 1966 through 1967

## Legal status

Main article: Space law

Although several pennants of the Soviet Union were scattered by Luna 2 in 1959 and by later landing missions, and U.S. flags have been symbolically planted on the Moon, no nation currently claims ownership of any part of the Moon's surface. Space law is an area of the Law that encompasses national and International law governing activities in Outer space. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Luna 2 (E-1A series was the second of the Soviet Union's Luna program spacecraft launched in the direction of the Moon. Flags of the United States The Flag of the United States of America consists of 13 equal horizontal stripes of Red (top and bottom alternating Russia and the U. S. are party to the Outer Space Treaty, which places the Moon under the same jurisdiction as international waters (res communis). Key points of the Treaty The Outer Space Treaty represents the basic legal framework of international space law International waterways Several international treaties have established freedom of navigation on semi-enclosed seas The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone This treaty also restricts the use of the Moon to peaceful purposes, explicitly banning military installations and weapons of mass destruction (including nuclear weapons). A weapon of mass destruction ( WMD) is a weapon which can kill large numbers of humans and/or cause great damage to man-made structures (e A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. [79]

A second treaty, the Moon Treaty, was proposed to restrict the exploitation of the Moon's resources by any single nation, but it has not been signed by any of the space-faring nations. Content The treaty makes a declaration that the Moon (which the treaty notes includes all celestial bodies for the purposes of language should be used for the benefit of all states This is a list of government agencies engaged in activities related to Outer space and Space exploration. Several individuals have made claims to the Moon in whole or in part, although none of these is generally considered credible. Extraterrestrial real estate is either land on other Planets or Natural satellites or parts of Space that is sold either through organizations or by individuals [80]

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43. ^ Taylor, G. J. (2006-11-08). Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1519 - Hernán Cortés enters Tenochtitlán and Aztec ruler Moctezuma welcomes him with great a Celebration Recent Gas Escape from the Moon. Hawai'i Institute of Geophysics and Planetology. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
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54. ^ Espenak, F. Saros Cycle. NASA. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
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56. ^ Total Lunar Occultations. Royal Astronomical Society of New Zealand. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
57. ^ Espenak, F. (2007). NASA Eclipse Home Page. NASA. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
58. ^ Mike Luciuk. How Bright is the Moon?. Retrieved on 7/3/08.
59. ^ Spekkens, K. (2002-10-18). See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. Events 1009 - The Church of the Holy Sepulchre, a Christian church in Jerusalem, is completely destroyed by the Fatimid Is the Moon seen as a crescent (and not a "boat") all over the world?. Curious About Astronomy. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
60. ^ Coren, M. "'Giant leap' opens world of possibility", CNN. com, 2004-07-26. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Events 657 - Battle of Siffin. 811 - Battle of Pliska; Byzantine Emperor Nicephorus Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
61. ^ (1977-09-01). Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays Events 462 - Possible start of first Byzantine indiction cycle. "NASA news release 77-47 page 242". Press release. A news release, media release, press release or press statement is a written or recorded Communication directed at members of the News Retrieved on 2007-08-29. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 708 - Copper coins are minted in Japan for the first time (Traditional Japanese date: August 10, 708)
62. ^ Appleton, James; Charles Radley, John Deans, Simon Harvey, Paul Burt, Michael Haxell, Roy Adams, N Spooner and Wayne Brieske. "OASI Newsletters Archive", 1977. Retrieved on 2007-08-29. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 708 - Copper coins are minted in Japan for the first time (Traditional Japanese date: August 10, 708)
63. ^ Dickey, J. ; et al. (1994). "Lunar laser ranging: a continuing legacy of the Apollo program". Science 265: 482–490. doi:10.1126/science.265.5171.482. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
64. ^ NASA (2004-12-14). "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Events 1287 - St Lucia's flood: The Zuider Zee sea wall in the Netherlands collapses killing over 50000 people "President Bush Offers New Vision For NASA". Press release. A news release, media release, press release or press statement is a written or recorded Communication directed at members of the News Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
65. ^ NASA (2006-12-04). Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. "December 4th" redirects here For the song by Jay-Z, see December 4th (song. "NASA Unveils Global Exploration Strategy and Lunar Architecture". Press release. A news release, media release, press release or press statement is a written or recorded Communication directed at members of the News Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
66. ^ “嫦娥一号”发射时间确定 但未到公布时机. XINHUA Online (July 7, 2007). Retrieved on July 12, 2007. Events 1191 - Saladin 's garrison surrenders ending the two-year Siege of Acre. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
67. ^ Kalam visualises establishing space industry. The Hindu (2006-09-21). Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1217 - The Estonian tribal leader Lembitu of Lehola was killed in a battle against Teutonic Knights. Retrieved on 2007-08-28. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 475 - The Roman General Orestes forces western Roman Emperor Julius Nepos to flee his Capital
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69. ^ Japan Embarks on the Largest Moon Mission Since Apollo
70. ^ Carved and Drawn Prehistoric Maps of the Cosmos. Space Today Online (2006). Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
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72. ^ Lewis, C.S. (1964). Clive Staples Lewis (29 November 1898 – 22 November 1963 The Discarded Image. Cambridge: Cambridge University Press, 108. ISBN 0-521047735-2.
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77. ^ Van Helden, A. (1995). The Moon. Galileo Project. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
78. ^ Boese, A. (2002). The Great Moon Hoax. Museum of Hoaxes. Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
79. ^ International Space Law. United Nations Office for Outer Space Affairs (2006). Retrieved on 2007-04-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
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General
• Bussey, B. ; Spudis, P.D. (2004). Paul D Spudis is an American Geologist and lunar scientist In 1976 he earned a B The Clementine Atlas of the Moon. Cambridge University Press. ISBN 0-521-81528-2.
• Jolliff, B. ; Wieczorek, M. ; Shearer, C. ; Neal, C. (eds. ) (2006). "New views of the Moon". Rev. Mineral. Geochem. 60: 721. Chantilly, Virginia: Min. Soc. Amer. .
• Mackenzie, Dana (2003). The Big Splat, or How Our Moon Came to Be. Hoboken, New Jersey: John Wiley & Sons, Inc.
• Moore, P. (2001). Sir Alfred Patrick Caldwell-Moore, CBE, HonFRS, FRAS (born 4 March 1923 in Pinner) known as Patrick Moore, is On the Moon. Tucson, Arizona: Sterling Publishing Co. . ISBN 0-304-35469-4.
• Spudis, P. D. (1996). The Once and Future Moon. Smithsonian Institution Press. ISBN 1-56098-634-4.
• Taylor, S. R. (1992). Solar system evolution. Cambridge Univ. Press, 307.
• Wilhelms, D. E. (1987). "Geologic History of the Moon". U. S. Geological Survey Professional paper 1348.
• Wilhelms, D. E. (1993). To a Rocky Moon: A Geologist's History of Lunar Exploration. Tucson, Arizona: University of Arizona Press.