The far side of the Moon is the hemisphere of the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

that is facing away from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

, the opposite hemisphere is the near side. It always has the same surface oriented away from Earth because of

synchronous rotation Tidal locking between a pair of co-orbiting astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked ...

in the Moon's

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

. Compared to the near side, the far side's terrain is rugged, with a multitude of

impact craters An impact crater is a depression in the surface of a solid astronomical body formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically ...

and relatively few flat and dark lunar maria ("seas"), giving it an appearance closer to other barren places in the Solar System such as Mercury and

Callisto CALLISTO (''Cooperative Action Leading to Launcher Innovation in Stage Toss-back Operations'') is a reusable VTVL Prototype, demonstrator propelled by a small 40 kN Japanese LOX-LH2 rocket engine. It is being developed jointly by the CNES, French ...

. It has one of the largest craters in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, the South Pole–Aitken basin. The hemisphere has sometimes been called the "Dark side of the Moon", where "dark" means "unknown" instead of "lacking sunlight" each location on the Moon experiences two weeks of

sunlight Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...

while the opposite location experiences night. About 18 percent of the far side is occasionally visible from Earth due to oscillation and to

libration In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon that is perceived by observers on the Earth and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see ...

. The remaining 82 percent remained unobserved until 1959, when it was photographed by the Soviet

Luna 3 Luna 3, or E-2A No.1 (), was a Soviet spacecraft launched in 1959 as part of the Luna programme. It was the first mission to photograph the far side of the Moon and the third Soviet space probe to be sent to the neighborhood of the Moon. The hi ...

space probe. The

Soviet Academy of Sciences The Academy of Sciences of the Soviet Union was the highest scientific institution of the Soviet Union from 1925 to 1991. It united the country's leading scientists and was subordinated directly to the Council of Ministers of the Soviet Union (un ...

published the first atlas of the far side in 1960. The

Apollo 8 Apollo 8 (December 21–27, 1968) was the first crewed spacecraft to leave Sphere of influence (astrodynamics), Earth's gravitational sphere of influence, and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times ...

astronauts were the first humans to see the far side in person when they orbited the Moon in 1968. All crewed and uncrewed

soft landing A soft landing is any type of aircraft, rocket or spacecraft landing that does not result in significant damage to or destruction of the vehicle or its payload, as opposed to a hard landing. The average vertical speed in a soft landing should b ...

s had taken place on the

near side of the Moon The near side of the Moon is the lunar hemisphere that faces Earth, opposite to the far side. The near side of the Moon has always the same lunar surface (or "face") oriented to Earth, due to the Moon rotating on its axis at the same rate that ...

, until January 3, 2019, when the

Chang'e 4 Chang'e 4 (; ) is a robotic spacecraft mission in the Chinese Lunar Exploration Program of the CNSA. It made a soft landing on the far side of the Moon, the first spacecraft to do so, on 3 January 2019. A communication relay satellite, , w ...

spacecraft made the first landing on the far side. The

Chang'e 6 Chang'e 6 () was the sixth robotic lunar exploration mission by the China National Space Administration (CNSA) and the second CNSA lunar sample-return mission. Like its predecessors in the Chinese Lunar Exploration Program, the spacecraft is ...

sample-return mission A sample-return mission is a spacecraft mission to collect and return samples from an extraterrestrial location to Earth for analysis. Sample-return missions may bring back merely atoms and molecules or a deposit of complex compounds such as lo ...

was launched on May 3, 2024, landed in the Apollo basin in the southern hemisphere of the lunar far side and returned to Earth a month later on June 25 with humanity's first lunar samples retrieved from the far side. Astronomers have suggested installing a large

radio telescope A radio telescope is a specialized antenna (radio), antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the r ...

on the far side, where the Moon would shield it from possible radio interference from Earth. Yutu-2 leaving Chang e-4-iau1901a

Definition

Tidal force The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the ...

s from

have slowed the Moon's rotation to the point where the same side is always facing the Earth—a phenomenon called

tidal locking Tidal locking between a pair of co-orbiting astronomical body, astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where ...

. The other face, most of which is never visible from the Earth, is therefore called the "far side of the Moon". Over time, some crescent-shaped edges of the far side can be seen due to

. In total, 59 percent of the Moon's surface is visible from Earth at one time or another. Useful observation of the parts of the far side of the Moon occasionally visible from Earth is difficult because of the low

viewing angle In display technology parlance, viewing angle is the angle at which a display can be viewed with an acceptable visual performance. In a technical context, the angular range is called viewing cone defined by a multitude of viewing directions. Th ...

from Earth (they cannot be observed "full on"). A common misconception is that the Moon does not rotate on its axis. If that were so, the whole of the Moon would be visible to Earth over the course of its orbit. Instead, its rotation period matches its orbital period, meaning it turns around once for every orbit it makes: in Earth terms, it could be said that its

day A day is the time rotation period, period of a full Earth's rotation, rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, ...

and its year have the same length (i.e., ~29.5 earth days). The phrase "dark side of the Moon" does not refer to "dark" as in the absence of light, but rather "dark" as in unknown: until humans were able to send spacecraft around the Moon, this area had never been seen. In reality, both the near and far sides receive (on average) almost equal amounts of light directly from the Sun. This symmetry is complicated by sunlight reflected from the Earth onto the near side ( earthshine), and by lunar eclipses, which occur only when the far side is already dark. Lunar eclipses mean that the side facing earth receives fractionally less sunlight than the far side when considered over a long period of time. At night under a "full Earth" the near side of the Moon receives on the order of 10

lux The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the irradiance, as perceived by ...

of illumination (about what a city sidewalk under streetlights gets; this is 34 times more light than is received on Earth under a full Moon) whereas the far side of the Moon during the lunar night receives only about 0.001 lux of starlight. Only during a full Moon (as viewed from Earth) is the whole far side of the Moon dark. The word ''dark'' has expanded to refer also to the fact that communication with spacecraft can be blocked while the spacecraft is on the far side of the Moon, during Apollo space missions for example.

Differences

The two hemispheres of the Moon have dramatically different appearances, with the near side covered in multiple, large ''maria'' (Latin for 'seas', since the earliest astronomers incorrectly thought that these plains were seas of

lunar water The search for the presence of lunar water has attracted considerable attention and motivated several recent lunar missions, largely because of water's usefulness in making long-term lunar habitation feasible. The Moon is believed to be genera ...

). The far side has a battered, densely cratered appearance with few maria. Only 1% of the surface of the far side is covered by maria, compared to 31.2% on the near side. One commonly accepted 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 ''Lunar Prospector'' was a spacecraft that orbited the Moon for 19 months in 1998-99. From a low polar orbit, it mapped surface composition including lunar hydrogen deposits, measured magnetic and gravity fields, and studied lunar outgassing e ...

gamma-ray spectrometer A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see Gamma spectroscopy#Scintillation detectors, figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of ...

. While other factors, such as surface elevation and crustal thickness, could also affect where

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

s erupt, these do not explain why the far side South Pole–Aitken basin (which contains the lowest elevations of the Moon and possesses a thin crust) was not as volcanically active as

Oceanus Procellarum Oceanus Procellarum ( ; from ) is a vast lunar mare on the western edge of the near side of the Moon. It is the only one of the lunar maria to be called an "Oceanus" (ocean), due to its size: Oceanus Procellarum is the largest of the maria ("s ...

on the near side. It has also been proposed that the differences between the two hemispheres may have been caused by a collision with a smaller companion moon that also originated from the Theia collision. In this model, the impact led to an accretionary pile rather than a crater, contributing a hemispheric layer of extent and thickness that may be consistent with the dimensions of the far side highlands. The chemical composition of the far side is inconsistent with this model. The far side has more visible craters. This is thought to be a result of the effects of lunar lava flows, which cover and obscure craters, rather than a shielding effect from the Earth.

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

calculates that the Earth obscures only about 4

square degree __NOTOC__ A square degree (deg2) is a non- SI unit measure of solid angle. Other denotations include ''sq. deg.'' and (°)2. Just as degrees are used to measure parts of a circle, square degrees are used to measure parts of a sphere. Analogous ...

s out of 41,000 square degrees of the sky as seen from the Moon. "This makes the Earth negligible as a shield for the Moon ndit is likely that each side of the Moon has received equal numbers of impacts, but the resurfacing by lava results in fewer craters visible on the near side than the far side, even though both sides have received the same number of impacts." Newer research suggests that heat from Earth at the time when the Moon was formed is the reason the near side has fewer impact craters. The lunar crust consists primarily of

plagioclase Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continu ...

s formed when

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

and

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

condensed and combined with

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

s in the mantle. The cooler far side experienced condensation of these elements sooner and so formed a thicker crust;

meteoroid A meteoroid ( ) is a small rocky or metallic body in outer space. Meteoroids are distinguished as objects significantly smaller than ''asteroids'', ranging in size from grains to objects up to wide. Objects smaller than meteoroids are classifie ...

impacts on the near side would sometimes penetrate the thinner crust here and release basaltic lava that created the maria, but would rarely do so on the far side. The far side exhibits more extreme variations in terrain elevation than the near side. The Moon's highest and lowest points, along with its tallest mountains measured from base to peak, are all located on the far side.

Exploration

Early exploration

Until the late 1950s, little was known about the far side of the Moon. Librations periodically allowed limited glimpses of features near the lunar limb on the far side, but only up to 59% of the total surface of the Moon. These features were seen from a low angle, hindering useful observation (it proved difficult to distinguish a crater from a mountain range). The remaining 82% of the surface on the far side remained unknown, and its properties were subject to much speculation. An example of a far side feature that can be seen through libration is the

Mare Orientale Mare Orientale (Latin ''orientāle'', the "eastern sea") is a lunar mare. It is located on the western border of the near side and far side of the Moon, and is difficult to see from an Earthbound perspective. Images from spacecraft have revea ...

, which is a prominent impact basin spanning almost , yet this was not even named as a feature until 1906, by Julius Franz in ''Der Mond''. The true nature of the basin was discovered in the 1960s when rectified images were projected onto a globe. The basin was photographed in fine detail by

Lunar Orbiter 4 Lunar Orbiter 4 was a robotic U.S. spacecraft, part of the Lunar Orbiter program, Lunar Orbiter Program, designed to orbit the Moon, after the three previous orbiters had completed the required needs for Project Apollo, Apollo mapping and site s ...

in 1967. Before space exploration began, astronomers expected that the far side would be similar to the side visible to Earth. On 7 October 1959, the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

probe

took the first photographs of the lunar far side, eighteen of them resolvable, covering one-third of the surface invisible from the Earth.Луна (спутник Земли)

Great Soviet Encyclopedia The ''Great Soviet Encyclopedia'' (GSE; , ''BSE'') is one of the largest Russian-language encyclopedias, published in the Soviet Union from 1926 to 1990. After 2002, the encyclopedia's data was partially included into the later ''Great Russian Enc ...

The images were analysed, and the first atlas of the far side of the Moon was published by the

USSR Academy of Sciences The Academy of Sciences of the Soviet Union was the highest scientific institution of the Soviet Union from 1925 to 1991. It united the country's leading scientists and was subordinated directly to the Council of Ministers of the Soviet Union (u ...

on 6 November 1960. It included a catalog of 500 distinguished features of the landscape. In 1961, the first globe (1: scale)Moon maps and globes, created with the participation of Lunar and Planetary Research Department of SAI
SAI containing lunar features invisible from the Earth was released in the

USSR The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

, based on images from Luna 3. On 20 July 1965, another Soviet probe, Zond 3, transmitted 25 pictures of very good quality of the lunar far side, with much better resolution than those from Luna 3. In particular, they revealed chains of craters, hundreds of kilometers in length, but, unexpectedly, no mare plains like those visible from Earth with the naked eye. In 1967, the second part of the ''Atlas of the Far Side of the Moon'' was published in

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

, based on data from Zond 3, with the catalog now including 4,000 newly discovered features of the lunar far side landscape. In the same year, the first ''Complete Map of the Moon'' (1: scale) and updated complete globe (1: scale), featuring 95 percent of the lunar surface, were released in the Soviet Union. As many prominent landscape features of the far side were discovered by Soviet space probes, Soviet scientists selected names for them. This caused some controversy, though the Soviet Academy of Sciences selected many non-Soviet names, including

Jules Verne Jules Gabriel Verne (;''Longman Pronunciation Dictionary''. ; 8 February 1828 – 24 March 1905) was a French novelist, poet and playwright. His collaboration with the publisher Pierre-Jules Hetzel led to the creation of the ''Voyages extraor ...

Marie Curie Maria Salomea Skłodowska-Curie (; ; 7 November 1867 – 4 July 1934), known simply as Marie Curie ( ; ), was a Polish and naturalised-French physicist and chemist who conducted pioneering research on radioactivity. She was List of female ...

and

Thomas Edison Thomas Alva Edison (February11, 1847October18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, ...

. The

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

later accepted many of the names.

Further survey mission

On 26 April 1962,

Ranger 4 Ranger 4 was a spacecraft of the Ranger program, launched in 1962. It was designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to crashing upon the Moon, to rough-land a seismometer ca ...

space probe became the first spacecraft to impact the far side of the Moon, although it failed to return any scientific data before impact. The first truly comprehensive and detailed mapping survey of the far side was undertaken by the American uncrewed

Lunar Orbiter program The Lunar Orbiter program was a series of five uncrewed lunar orbiter missions launched by the United States in 1966 and 1967. Intended to help select Apollo landing sites by mapping the Moon's surface, they provided the first photographs from ...

launched by NASA from 1966 to 1967. Most of the coverage of the far side was provided by the final probe in the series,

Lunar Orbiter 5 Lunar Orbiter 5, the last of the "Lunar Orbiter series", was designed to take additional Project Apollo, Apollo and Surveyor program, Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far sid ...

. The far side was first seen directly by human eyes during the

mission in December, 1968. Astronaut

William Anders William Alison Anders (17 October 1933 – 7 June 2024) was an American United States Air Force (USAF) major general, electrical engineer, nuclear engineer, NASA astronaut, and businessman. In December 1968, he was a member of the crew of ...

described the view: It has been seen by all 24 men who flew on

and

Apollo 10 Apollo 10 (May 18–26, 1969) was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing (Apollo 11, two ...

through

Apollo 17 Apollo 17 (December 7–19, 1972) was the eleventh and final mission of NASA's Apollo program, the sixth and most recent time humans have set foot on the Moon. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on the Moon, ...

, and photographed by multiple lunar probes. Spacecraft passing behind the Moon were out of direct radio communication with the Earth, and had to wait until the orbit allowed transmission. During the Apollo missions, the main engine of the Service Module was fired when the vessel was behind the Moon, producing some tense moments in

Mission Control A mission control center (MCC, sometimes called a flight control center or operations center) is a facility that manages space flights, usually from the point of launch until landing or the end of the mission. It is part of the ground segment ...

before the craft reappeared. Geologist-astronaut

Harrison Schmitt Harrison Hagan "Jack" Schmitt (born July 3, 1935) is an American geologist, former NASA astronaut, university professor, former U.S. senator from New Mexico. He is the most recent living person—and only person without a background in military a ...

, who became the last to step onto the Moon, had aggressively lobbied for Apollo 17's landing site to be on the far side of the Moon, targeting the lava-filled crater Tsiolkovskiy. Schmitt's ambitious proposal included a special communications satellite based on the existing TIROS satellites to be launched into a Farquhar–Lissajous halo orbit around the L2 point so as to maintain line-of-sight contact with the astronauts during their powered descent and lunar surface operations. NASA administrators rejected these plans on the grounds of added risk and lack of funding. The idea of utilizing the Earth–Moon for a

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

covering the Moon's far side has been realized, as

China National Space Administration The China National Space Administration (CNSA) is a government agency of the People's Republic of China headquartered in Haidian District, Haidian, Beijing, responsible for civil space administration and international space cooperation. These ...

launched the Queqiao relay satellite in 2018. It has since been used for communications between the

lander and

Yutu 2 ''Yutu-2'' () is the robotic lunar rover component of China National Space Administration, CNSA's Chang'e 4 mission to the Moon, launched on 7 December 2018 18:23 UTC, it entered lunar orbit on 12 December 2018 before making the first soft land ...

rover, which successfully landed in early 2019 on the lunar far side, and ground stations on the Earth. L2 is proposed to be "an ideal location" for a

propellant depot An orbital propellant depot is a cache of propellant that is placed in orbit around Earth or another body to allow spacecraft or the transfer stage of the spacecraft to be fueled in space. It is one of the types of space resource depots that ha ...

as part of the proposed depot-based space transportation architecture.

Soft landing

The China National Space Administration (CNSA)'s

achieved humanity's first ever soft landing on the lunar far side on 3 January 2019 and deployed the

Yutu-2 ''Yutu-2'' () is the robotic lunar rover component of China National Space Administration, CNSA's Chang'e 4 mission to the Moon, launched on 7 December 2018 18:23 UTC, it entered lunar orbit on 12 December 2018 before making the first soft land ...

lunar rover onto the lunar surface. The craft included a lander equipped with a low-frequency radio

spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...

and geological research tools. The far side of the Moon provides a good environment for

radio astronomy Radio astronomy is a subfield of astronomy that studies Astronomical object, celestial objects using radio waves. It started in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observat ...

as interferences from the Earth are blocked by the Moon. In February 2020, Chinese astronomers reported, for the first time, a high-resolution image of a lunar ejecta sequence, as well as direct analysis of its internal architecture. These were based on observations made by the Lunar Penetrating Radar (LPR) on board the

rover. CNSA launched

on 3 May 2024, which conducted the first lunar sample return from Apollo Basin on the far side of the Moon. It was CNSA's second lunar sample return mission, the first achieved by

Chang'e 5 Chang'e 5 () was the fifth lunar exploration mission in the Chinese Lunar Exploration Program of CNSA, and China's first lunar sample-return mission. Like its predecessors, the spacecraft is named after the Chinese moon goddess, Chang'e. ...

from the lunar near side four years earlier. It also carried a mini "Jinchan" rover to conduct

infrared spectroscopy Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functio ...

of lunar surface and imaged the Chang'e 6's lander on the lunar surface. The lander-ascender-rover combination was separated with the orbiter and returner before landing on 1 June 2024 at 22:23 UTC. It landed on the Moon's surface on 1 June 2024. The ascender was launched back to lunar orbit on 3 June 2024 at 23:38 UTC, carrying samples collected by the lander, and later completed another robotic rendezvous and docking in lunar orbit. The sample container was then transferred to the returner, which landed in

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an Autonomous regions of China, autonomous region of China. Its border includes two-thirds of the length of China's China–Mongolia border, border with the country of Mongolia. ...

on 25 June 2024, completing China's far side sample return mission. The Lunar Surface Electromagnetics Experiment (LuSEE-Night) lander, a mission to soft land as early as 2026 a robotic observatory on the far side designed to measure electromagnetic waves from the early history of the

universe The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...

is being developed by

and the United States Department of Energy.

Potential uses and missions

Because the far side of the Moon is shielded from radio transmissions from the Earth, it is considered a good location for placing

s for use by

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

s. Small, bowl-shaped craters provide a natural formation for a stationary

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

similar to

Arecibo Arecibo (; ) is a Arecibo barrio-pueblo, city and Municipalities of Puerto Rico, municipality on the northern coast of Puerto Rico, on the shores of the Atlantic Ocean, located north of Utuado, Puerto Rico, Utuado and Ciales, Puerto Rico, Ciale ...

Puerto Rico ; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...

. For much larger-scale telescopes, the crater Daedalus is situated near the center of the far side, and the rim would help to block stray communications from orbiting satellites. Another potential candidate for a radio telescope is the Saha crater. Before deploying radio telescopes to the far side, several problems must be overcome. The fine lunar dust can contaminate equipment, vehicles, and space suits. The conducting materials used for the radio dishes must also be carefully shielded against the effects of

solar flare A solar flare is a relatively intense, localized emission of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and ot ...

s. Finally, the area around the telescopes must be protected against contamination by other radio sources. The

Lagrange point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the gravitational influence of two massive orbiting bodies. Mathematically, this involves t ...

of the Earth–Moon system is located about above the far side, which has also been proposed as a location for a future radio telescope which would perform a Lissajous orbit about the Lagrangian point. One of the NASA missions to the Moon under study would send a sample-return lander to the South Pole–Aitken basin, the location of a major impact event that created a formation nearly across. The force of this impact has created a deep penetration into the lunar surface, and a sample returned from this site could be analyzed for information concerning the interior of the Moon. Because the near side is partly shielded from the

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

by the Earth, the far side maria are expected to have the highest concentration of

helium-3 Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and hydrogen-1 are the only stable nuclides with ...

on the surface of the Moon. This

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

is relatively rare on the Earth, but has good potential for use as a fuel in fusion reactors. Proponents of lunar settlement have cited the presence of this material as a reason for developing a Moon base.

Named features

* Aitken (crater) *

Amici (crater) Amici is a lunar impact crater that is located on the rugged far side of the Moon. It lies to the south of the larger crater Icarus, to the north of McKellar. The rim of Amici has been eroded and distorted by subsequent impacts, so that is ...

* Anuchin (crater) *

Apollo (crater) Apollo, also called the Apollo basin, is a large impact crater located on the far side of the Moon, in the southern hemisphere. It was previously known as Basin XVI; in 1970 it was officially named after the Apollo missions by the Internationa ...

Avogadro (crater) Avogadro is an ancient lunar impact crater that is located in the northern hemisphere on the far side of the Moon. The formation has been heavily worn and eroded by subsequent impacts, so that the rim is now little more than a rounded edge sur ...

* Bel'kovich (crater) *

Belopol'skiy (crater) Aristarkh Apollonovich Belopolsky (Аристарх Аполлонович Белопольский; – 16 May 1934) was a Russian and later Soviet astronomer. He was born in Moscow but his father's ancestors are from a Serbian town called B ...

* Bergstrand (crater) * Berkner (crater) *

Birkhoff (crater) Birkhoff is a giant lunar walled plain that is located on the far side of the Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times E ...

Bjerknes (lunar crater) Bjerknes is a Lunar craters, lunar impact crater that is located in the southern sphere, hemisphere on the rugged Far side (Moon), far side of the Moon. The crater lies behind the southeastern limb, and beyond the region that is sometimes bro ...

Bok (lunar crater) Bok is a Lunar craters, lunar impact crater that is located on the Far side (Moon), far side of the Moon. To the southeast is the crater Sniadecki (crater), Sniadecki; to the north is McKellar (crater), McKellar, and further to the west is De ...

Campbell (lunar crater) Campbell is a large Lunar craters, lunar impact crater that is located in the northern hemisphere on the Far side (Moon), far side of the Moon. It lies to the southwest of the walled plain D'Alembert (crater), D'Alembert, an even larger formation ...

* Cantor (crater) *

Carnot (crater) Carnot is a large crater in the northern part of the Moon's far side. It was named after Nicolas L. S. Carnot by the IAU in 1970. The outer rim of Carnot has a somewhat hexagonal form, particularly in the southern half. The northern rim has ...

Cassegrain (crater) Cassegrain is a Lunar craters, lunar impact crater that is located on the Far side (Moon), far side of the Moon, beyond the southeastern limb. It lies to the southeast of the larger crater Lebedev (crater), Lebedev, and to the northeast of the comp ...

Chandler (crater) Chandler is a lunar impact crater in the northern hemisphere, on the Moon's far side. It lies to the southeast of the large walled plain D'Alembert, and southeast of the slightly smaller Chernyshev crater. This is a heavily worn and eroded cra ...

Chappell (crater) Chappell is a lunar impact crater on the far side of the Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's di ...

* Chernyshev (crater) * Comrie (crater) *

Coulomb-Sarton Basin The Coulomb-Sarton Basin is a Pre-Nectarian Impact crater, impact basin on the far side of the Moon. It is named after the crater Coulomb (crater), Coulomb northeast of the center of the basin and the smaller crater Sarton (crater), Sarton just s ...

Crookes (crater) Crookes is a lunar impact crater that lies on the Moon's far side as seen from the Earth. It lies just to the southwest of the giant crater Korolev. To the southwest of Crookes is McKellar. The rim of this crater has a relatively high albed ...

d'Alembert (crater) d'Alembert is a large lunar impact crater located in the northern hemisphere on the far side of the Moon, to the northeast of the somewhat smaller walled plain Campbell. Astride the southwest rim of d'Alembert is Slipher. To the north is the ...

Daedalus (crater) Daedalus is a prominent crater located near the center of the far side of the Moon. The inner wall is terraced, and there is a cluster of central peaks on the relatively flat floor. Because of its location (shielded from radio emissions from ...

* Davisson (crater) *

Debus (crater) Debus is a small lunar impact crater that is located on the far side of the Moon, past the eastern limb. It lies to the east-southeast of the crater Ganskiy, and just to the west of the huge walled plain Pasteur. This is a circular crater wit ...

* Delporte (crater) *

Dyson (crater) Dyson is a Lunar craters, lunar impact crater, 63 kilometers in diameter, that lies on the Far side (Moon), far side of the Moon, past the northwest limb. It is located in the northern part of the surface, to the northwest of the crater Coulomb (c ...

* Ellerman (crater) *

Emden (crater) Emden is a lunar impact crater that is located in the northern hemisphere on the far side of the Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; a ...

* Esnault-Pelterie (crater) * Finsen (crater) *

Fleming (crater) Fleming is a large lunar impact crater that is located on the Moon's far side, and cannot be seen from the Earth. It lies about a crater diameter to the east-northeast of Hertz, and to the northwest of Lobachevskiy. The low rim of this format ...

* Fowler (crater) *

Fridman (crater) Fridman is the remains of a lunar impact crater on the far side of the Moon. It lies due south of the huge walled plain Hertzsprung, and is attached to the northeastern rim of the crater Ioffe. This crater lies in the southern part of the eje ...

Ganskiy (crater) Ganskiy is a lunar impact crater that is located on the far side of the Moon. It lies to the southeast of the walled plain Hirayama. The rim of this crater is roughly circular, with a slight hexagonal appearance. There is some wear along th ...

Gerasimovich (crater) Gerasimovich is a Lunar craters, lunar impact crater on the Far side (Moon), far side of the Moon. It lies beyond the western limb, to the west-northwest of the immense Mare Orientale impact basin. The outer blanket of ejecta from this impact rea ...

* Gullstrand (crater) *

Hayn (crater) Hayn is a lunar impact crater that lies next to the northeast limb of the Moon. This location restricts the amount of detail that can be viewed from the Earth, as the western inner side is permanently hidden from sight. Observation of this crater ...

* Hegu (crater) *

Hertzsprung (crater) Hertzsprung is an enormous Lunar craters, lunar impact crater, or impact basin, that is located on the Far side (Moon), far side of the Moon, beyond the western limb. In dimension, this formation is larger than several of the lunar mare areas on t ...

* H. G. Wells (crater) *

Hippocrates (lunar crater) Hippocrates is a lunar impact crater on the far side of the Moon. It is located in the northern region of the lunar surface, to the north of the crater Stebbins. To the southwest of Hippocrates are Kirkwood and the large Sommerfeld. This i ...

* Houzeau (crater) *

Icarus (crater) Icarus is a Lunar craters, lunar impact crater that lies on the Moon's Far side (Moon), far side. It is located to the west of the huge walled plain Korolev (lunar crater), Korolev, and less than two crater diameters to the east of the crater D ...

Ioffe (crater) Ioffe is a lunar impact crater on the far side of the Moon. It lies to the south of the walled plain Hertzsprung, and is attached to the southwestern outer rim of Fridman. Only a short stretch of terrain separates Ioffe from Belopol'skiy to ...

* Izsak (crater) * Jenner (crater) * Kamerlingh Onnes (crater) *

Kirkwood (crater) Kirkwood is a well-formed lunar impact crater that is located on the far side of the Moon, on the northern hemisphere, approximately 68 kilometers in diameter. It lies just to the northeast of the crater Sommerfeld, and Hippocrates is locate ...

* Klute (crater) * Kolhörster (crater) * Komarov (crater) *

Korolev (lunar crater) Korolev is a large lunar impact crater of the walled plain or basin type. It is a basin of Nectarian age. Korolev is named for Soviet rocket engineer Sergei Korolev. It lies on the far side of the Moon, and the northern part of its floor cross ...

* Kovalevskaya (crater) * Krasovskiy (crater) *

Kugler (crater) Kugler is a lunar impact crater that lies in the southern hemisphere on the far side of the Moon. It is located just past the southeast limb of the Moon's surface, in the proximity of the libration zone that is occasionally brought into sight. ...

* Kulik (crater) * Lamb (crater) * Lacus Luxuriae * Lacus Oblivionis *

Lander (crater) Lander is a lunar impact crater that is located just to the north-northeast of the prominent Tsiolkovskiy, on the far side of the Moon. It was named by the IAU in 1976 for the British explorer Richard Lander.Langevin (crater) * Lebedev (crater) * Leibnitz (crater) *

Lucretius (crater) Lucretius is an impact crater on the far side of the Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diamet ...

Lunar south pole The lunar south pole is the southernmost point on the Moon. It is of interest to scientists because of the lunar water, occurrence of water ice in Crater of eternal darkness, permanently shadowed areas around it. The lunar south pole region fea ...

* Maksutov (crater) *

McKellar (crater) McKellar is a lunar impact crater on the Moon's far side, and it cannot be viewed directly from the Earth. It lies to the southwest of the crater Crookes, and the ray system from this impact covers the floor and sides of McKellar. To the sout ...

* Mare Australe *

Mare Frigoris Mare Frigoris (Latin ''frīgōris'', the "Sea of Cold") is a lunar mare in the far north of the Moon. It is located in the outer rings of the Procellarum basin, just north of Mare Imbrium, and stretches east to north of Mare Serenitatis. It is j ...

Mare Humboldtianum Mare Humboldtianum (Latin ''humboldtiānum'', the "Sea of Alexander von Humboldt") is a lunar mare located just to the east of Mare Frigoris, in the center of Humboldtianum basin. It is located along the northeastern limb of the Moon, and cont ...

* Mare Ingenii * Mare Moscoviense *

Mendeleev (crater) Mendeleev is a large lunar impact crater that is located on the far side of the Moon, as seen from the Earth. The southern rim of this walled plain just crosses the lunar equator. Intruding into the eastern rim of Mendeleev is the crater Sch ...

* Michelson (crater) *

Montes Cordillera Montes Cordillera is a mountain range on the Moon. This feature forms the outer ring of peaks surrounding the Mare Orientale impact basin, with the inner ring formed by the Montes Rook. The center of the range is located at selenographic coordina ...

* Montes Rook * Mons Tai *

Nicholson (lunar crater) Nicholson is a lunar impact crater located at the western limb. In this position it is subject to libration, which can limit observation. The crater is also viewed at a very oblique angle, so it is seen from the side when observed from the Earth ...

* Nishina (crater) *

Ohm (crater) Ohm is a lunar impact crater that is located on the far side of the Moon. It lies to the south of the crater Comrie, and the satellite crater Comrie K is attached to Ohm's northeastern rim. To the northwest is the larger Shternberg, and to t ...

* Oppenheimer (crater) * Oresme (crater) * Pannekoek (crater) * Paraskevopoulos (crater) * Parenago (crater) * Patsaev (crater) *

Perrine (crater) Perrine is a lunar impact crater that is located on the northern hemisphere on the far side of the Moon. It lies to the west of the large walled plain Landau, and to the northeast of the crater Charlier. To the north-northwest is the smaller ...

Pettit (lunar crater) Pettit is a Lunar craters, lunar impact crater that lies near the western limb of the Moon. It was named after American astronomer Edison Pettit. In this location the crater is viewed nearly from the side by observers on Earth, and visibility can ...

* Pirquet (crater) * Pogson (crater) *

Priestley (lunar crater) Priestley is a lunar impact crater that is located on the far side of the Moon from the Earth, in the low southern latitudes. It lies to the southeast of the flooded crater Kugler. This is a worn crater with a rim and inner wall that have be ...

* Quetelet (crater) *

Rowland (crater) Rowland is a large Lunar craters, lunar impact crater that is located in the northern part of the Moon, on the Far side (Moon), far side from the Earth. This is an old, worn formation that is overlain by a number of smaller craters. The most not ...

* Sarton (crater) * Schlesinger (crater) *

Shaler (crater) Shaler is a lunar impact crater that lies on the southeast interior edge of the Montes Cordillera mountain ring that surrounds the immense Mare Orientale formation. It is located near the southwest limb of the Moon on the near side, and so is vi ...

* Shternberg (crater) *

Shuleykin (crater) Shuleykin is a small lunar impact crater that lies to the south of Mare Orientale, within the ring-shaped Montes Rook. It is located just on the far side of the Moon, but this area can be viewed from the Earth during periods of favorable libra ...

Sikorsky (crater) Sikorsky is a crater on the far side of the Moon. It is situated behind the southeastern limb of the Moon, just out of sight from the Earth. It lies to the northwest of the huge walled plain Schrödinger. To the northwest is the smaller crater ...

* Sniadecki (crater) *

Sommerfeld (crater) Sommerfeld is a sizable lunar impact crater situated in the far northern latitudes of the Moon. Located on the far side, it can only be observed from orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved ...

* South Pole–Aitken basin * Statio Tianhe (Chang'e 4 landing site) *

Stebbins (crater) Stebbins is a large lunar impact crater on the far side of the Moon. It is located along the north-northeastern rim of the even larger crater Birkhoff, with about one-third of Stebbins laid across the interior of Birkhoff. To the north of Ste ...

* Stoletov (crater) * Sverdrup (crater) * Tianjin (crater) *

Tikhov (lunar crater) Tikhov is an eroded Lunar craters, lunar impact crater on the Moon's Far side (Moon), far side. It is nearly attached to the east-southeastern outer rim of the larger crater Avogadro (crater), Avogadro. About one crater diameter the east-northe ...

* Titov (crater) * Tsander (crater) *

Tsinger (crater) Tsinger is a lunar impact crater that is located in the northern latitudes of the Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Ea ...

Tsiolkovskiy (crater) Tsiolkovskiy is a large lunar impact crater that is located on the far side of the Moon. Named for Russian scientist Konstantin Tsiolkovsky, it lies in the southern hemisphere, to the west of the large crater Gagarin, and northwest of Milne. ...

Tyndall (lunar crater) Tyndall is a relatively small lunar impact crater on the far side of the Moon, behind the southeastern limb. It is located very near the western outer rim of the larger crater Pizzetti, and the two are separated only by a few kilometers. To t ...

Vallis Bouvard Vallis Bouvard is a 284-km-long valley on the Moon, centered at . It begins at the southern rim of the crater Shaler, and winds its way to the south-southeast towards Baade. This is one of several such valleys that radiate away from the southeas ...

Vallis Inghirami Vallis Inghirami (latin for Inghirami Valley) is a valley on the Moon. Diameter of the valley is about 145 km. It is named after Giovanni Inghirami, and the name was approved by IAU The International Astronomical Union (IAU; , UAI) is an in ...

van't Hoff (crater) van't Hoff is a lunar impact crater named after Dutch chemist Jacobus H. van 't Hoff and is located to the northeast of the walled plain Birkhoff, on the far side of the Moon. To the northwest is the crater Stebbins, and to the east li ...

* Van de Graaff (crater) * Van der Waals (crater) * Vavilov (crater) * Vertregt (crater) * Virtanen (crater) * Volkov (crater) * Von Kármán (lunar crater) * Von Neumann (crater) * Von Zeipel (crater) * Wan-Hoo (crater) * Wiener (crater) *

Wright (lunar crater) Wright is a lunar impact crater that is located near the western limb of the Moon. It lies on the irregular plain between the Montes Cordillera and Montes Rook, two ring-shaped mountain ranges that surround the Mare Orientale. Just to the so ...

* Yamamoto (crater) * Zhinyu (crater)

Far side of Earth

While Earth is not tidally locked to the Moon, and therefore does not keep the same face turned away from the Moon, Earth has a "far side" to the Moon, which features a "far side"

tidal bulge The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the ...

pulled to the Moon.

References

External links

Lunar and Planetary Institute: Exploring the Moon

NASA takes first video of dark side of the Moon

Lunar and Planetary Institute: Lunar Atlases

* ttps://www.bibliotecapleyades.net/luna/moon_farsidemap.htm Full Moon Atlas: Lunar Far Side at lunarrepublic.com
Northwest Africa 482, only meteorite believed to have originated from the far side of the Moon

*
''LIFE'' magazine (Nov. 9, 1959) article about first photos.
{{Portal bar, Geology, Astronomy, Stars, Outer space, Solar System, Science Hemispheres Lunar science