The far side of the Moon is the lunar hemisphere that always faces away from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

, opposite to the

near side The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a ...

, 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 b ...

in the

Moon's orbit The Moon orbits Earth in the retrograde and prograde motion, prograde direction and completes one orbital period, revolution relative to the March Equinox, Vernal Equinox and the fixed stars, stars in about 27.32 days (a tropical month and sider ...

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

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

and relatively few flat and dark

lunar maria The lunar maria (; singular: mare ) are large, dark, basaltic plains on Earth's Moon, formed by ancient asteroid impacts on the far side on the Moon that triggered volcanic activity on the opposite (near) side. They were dubbed , Latin for 'seas' ...

("seas"), giving it an appearance closer to other barren places in the Solar System such as

Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

and

Callisto Callisto most commonly refers to: *Callisto (mythology), a nymph *Callisto (moon), a moon of Jupiter Callisto may also refer to: Art and entertainment *''Callisto series'', a sequence of novels by Lin Carter *''Callisto'', a novel by Torsten Kro ...

. 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 "Solar S ...

, the

South Pole–Aitken basin The South Pole–Aitken basin (SPA Basin, ) is an immense impact crater on the far side of the Moon. At roughly in diameter and between deep, it is one of the largest known impact craters in the Solar System. It is the largest, oldest, and dee ...

. The hemisphere is sometimes called the "dark side of the Moon", where "dark" means "unknown" instead of "lacking sunlight" each side of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

experiences two weeks of

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...

while the opposite side experiences two weeks of night. About 18 percent of the far side is occasionally visible from Earth due to

libration In lunar astronomy, libration is the wagging or wavering of the Moon perceived by Earth-bound observers and caused by changes in their perspective. It permits an observer to see slightly different hemispheres of the surface at different tim ...

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

Luna 3 Luna 3, or E-2A No.1 ( rus, Луна 3}) 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 th ...

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, uniting the country's leading scientists, subordinated directly to the Council of Ministers of the Soviet Union (until 1946 ...

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 low Earth orbit and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times without landing, and then departed safely back to Earth. These ...

astronauts were the first humans to see the far side in person when they orbited the Moon in 1968. All manned and unmanned soft landings had taken place on the

near side of the Moon The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a ...

, until 3 January 2019 when the

Chang'e 4 Chang'e 4 (; ) is a robotic spacecraft mission, part of the second phase of the Chinese Lunar Exploration Program. China achieved humanity's first soft landing on the far side of the Moon, on 3 January 2019. A communication relay satellit ...

spacecraft made the first landing on the far side. Astronomers have suggested installing a large

radio telescope A radio telescope is a specialized 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 radio frequency ...

on the far side, where the Moon would shield it from possible

radio interference Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrosta ...

from Earth.

Definition

Tidal force The tidal force is a gravitational effect that stretches a body along the line towards the center of mass of another body due to a gradient (difference in strength) in gravitational field from the other body; it is responsible for diverse phenomen ...

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 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 b ...

. 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 acceptable visual performance. In a technical context, the angular range is called viewing cone defined by a multitude of viewing directions. The vie ...

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 and its year have the same length (i.e., ~29.5 earth days). This is, as stated, a result of tidal locking. 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. While many misconstrue this to think that the "dark side" receives little to no sunlight, in reality, both the near and far sides receive (on average) almost equal amounts of light directly from the Sun. However, the near side also receives sunlight reflected from the Earth, known as

earthshine Earthlight is the diffuse reflection of sunlight reflected from Earth's surface and clouds. Earthshine (an example of planetshine), also known as the Moon's ashen glow, is the dim illumination of the otherwise unilluminated portion of the Moon ...

. Earthshine does not reach the area of the far side that cannot be seen from Earth. At night under a "full Earth" the near side of the Moon receives on the order of 10 lux 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 The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic coordinate system, ecliptic longitudes of the Sun and Moon opp ...

) whereas the dark 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 distinctly 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 Lunar water is water that is present on the Moon. Diffuse water molecules can persist at the Moon's sunlit surface, as discovered by NASA's SOFIA observatory in 2020. Gradually water vapor is decomposed by sunlight, leaving hydrogen and oxyg ...

). 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 the third mission selected by NASA for full development and construction as part of the Discovery Program. At a cost of $62.8 million, the 19-month mission was designed for a low polar orbit investigation of the Moon, ...

gamma-ray spectrometer A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of gamma-ray spectra for scientific and technic ...

. 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

(which contains the lowest elevations of the Moon and possesses a thin crust) was not as volcanically active as

Oceanus Procellarum Oceanus Procellarum ( la, Ōceanus procellārum, lit=Ocean of Storms) 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 Proc ...

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. However, the chemical composition of the far side is inconsistent with this model. The far side has more visible craters. This was 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 agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

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 to ...

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 tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more prope ...

s formed when

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

and

calcium Calcium is a chemical element with the 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 ...

condensed and combined with

silicate In chemistry, 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 al ...

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 defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as micr ...

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.

Exploration

Early exploration

Luna 3 grainy photo restoration and comparison with LRO

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, however, 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 reveale ...

, 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 did not expect that the far side would be different from the side visible to Earth. On 7 October 1959, the

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

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; ) 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 ''Bolshaya rossiyskaya e ...

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, uniting the country's leading scientists, subordinated directly to the Council of Ministers of the Soviet Union (until 1946 ...

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 Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...

, based on images from Luna 3. On 20 July 1965, another Soviet probe,

Zond 3 Zond 3 was a 1965 space probe which performed a flyby of the Moon far side, taking a number of quality photographs for its time. It was a member of the Soviet Zond program while also being part of the Mars 3MV project. It was unrelated to Zond s ...

, 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 ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...

, 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, and the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

, leaving many of those names intact, later assumed the role of naming lunar features on this hemisphere.

Further survey mission

On 26 April 1962, NASA's

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 c ...

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 unmanned

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

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 Apollo and Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far side. It was also equipped to collec ...

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

mission in December, 1968. Astronaut

William Anders William Alison Anders (born 17 October 1933) is a retired United States Air Force (USAF) major general, former electrical engineer, nuclear engineer, NASA astronaut, and businessman. In December 1968, he was a member of the crew of Apollo 8, ...

described the view: Back side of the Moon AS16-3021

It has been seen by all 27 crew members of the

and

Apollo 10 Apollo 10 (May 18–26, 1969) was a human spaceflight, the fourth crewed mission in the United States Apollo program, and the second (after Apollo8) to orbit the Moon. NASA described it as a "dress rehearsal" for the first Moon landing, and ...

through

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

missions, 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 before the craft reappeared. Geologist-astronaut

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

, who became the last to step onto the Moon, had aggressively lobbied for his 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 TIROS, or Television InfraRed Observation Satellite, is a series of early weather satellites launched by the United States, beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth, enablin ...

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 Earth–Moon for

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

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

China National Space Administration China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...

launched Queqiao relay satellite in 2018. It has since been used for communications between the Chang'e 4 lander and '' Yutu 2'' rover that have successfully landed in early 2019 on the lunar far side and ground stations on the Earth. And 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

's ''

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

Yutu-2 ''Yutu-2'' is the robotic lunar rover component of 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 landing on the far side of the Moon on 3 J ...

'' lunar rover onto far side 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 celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming f ...

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, and, as well, direct analysis of its internal architecture. These were based on observations made by the Lunar Penetrating Radar (LPR) on board the ''Yutu-2'' rover.

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 their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

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, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

similar to

Arecibo Arecibo (; ) is a city and municipality on the northern coast of Puerto Rico, on the shores of the Atlantic Ocean, located north of Utuado and Ciales; east of Hatillo; and west of Barceloneta and Florida. It is about west of San Juan, th ...

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

. 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 Lunar soil is the grain size, fine fraction of the regolith found on the selenography, surface of the Moon. Its properties can differ significantly from those of Soil, terrestrial soil. The physical properties of lunar soil are primarily the r ...

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 an intense localized eruption 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 other solar phe ...

s. Finally, the area around the telescopes must be protected against contamination by other radio sources. The Lagrange point 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 In orbital mechanics, a Lissajous orbit (), named after Jules Antoine Lissajous, is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system without requiring any propulsion. Lyapunov orbits ...

about the Lagrangian point. One of the NASA missions to the Moon under study would send a sample-return lander to the

, 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 upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...

by the Earth, the far side

maria Maria may refer to: People * Mary, mother of Jesus * Maria (given name), a popular given name in many languages Place names Extraterrestrial * 170 Maria, a Main belt S-type asteroid discovered in 1877 * Lunar maria (plural of ''mare''), large, ...

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 (the most common isotope, helium-4, having two protons and two neutrons in contrast). Other than protium (ordinary hydrogen), helium-3 is the ...

on the surface of the Moon. This

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

is relatively rare on the Earth, but has good potential for use as a fuel in

fusion Fusion, or synthesis, is the process of combining two or more distinct entities into a new whole. Fusion may also refer to: Science and technology Physics *Nuclear fusion, multiple atomic nuclei combining to form one or more different atomic nucl ...

reactors. Proponents of lunar settlement have cited the presence of this material as a reason for developing a Moon base.

Named features

Aitken (crater) Aitken is a large lunar crater, lunar impact crater that lies on the Far side (Moon), far side of the Moon, named for Robert Grant Aitken, an American astronomer specializing in binary stellar systems. It is located to the southeast of the cra ...

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 no ...

Anuchin (crater) Anuchin is a lunar impact crater that lies on the southern hemisphere on the far side of the Moon. It is located to the south of the larger crater Lamb Lamb or The Lamb may refer to: * A young sheep * Lamb and mutton, the meat of sheep Ar ...

Apollo (crater) Apollo is an enormous impact crater located in the southern hemisphere on the far side of the Moon. This formation dwarfs the large crater Oppenheimer that is located next to the western rim. The crater Barringer lies across the northern wall. To ...

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 surrou ...

* Bel'kovich (crater) *

Belopol'skiy (crater) Aristarkh Apollonovich Belopolsky (Аристарх Аполлонович Белопольский) (, Moscow – 16 May 1934, Pulkovo, Leningrad) was a Russian astronomer. He was born in Moscow but his father's ancestors are from a Serbian ...

* Bergstrand (crater) *

Berkner (crater) Berkner is a lunar impact crater that is located on the far side of the Moon, just past the western limb. It is attached to the east-southeast rim of the crater Parenago. Just to the south is the Robertson Robertson may refer to: People * Ro ...

Birkhoff (crater) Birkhoff is a giant lunar walled plain that is located on the far side of the Moon, in the northern hemisphere Hemisphere refers to: * A half of a sphere As half of the Earth * A hemisphere of Earth ** Northern Hemisphere ** Southern Hemis ...

* Bjerknes (lunar crater) *

Bok (lunar crater) Bok is a lunar impact crater that is located on the far side of the Moon. To the southeast is the crater Sniadecki; to the north is McKellar, and further to the west is De Vries De Vries is one of the most common Dutch surnames. It indi ...

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

Cantor (crater) Cantor is a lunar impact crater that is located on the northern hemisphere on the far side of the Moon. The outer rim of the crater has a distinctly hexagonal shape, and is slightly longer in the north–south direction. The interior walls are ...

Carnot (crater) Carnot is a large crater in the northern part of the Moon's far side. It intrudes into the southern rim of the huge walled plain Birkhoff. To the west-southwest of Carnot is the crater Paraskevopoulos. The outer rim of Carnot has a somewhat he ...

Cassegrain (crater) Cassegrain is a lunar impact crater that is located on the far side of the Moon, beyond the southeastern limb. It lies to the southeast of the larger crater Lebedev, and to the northeast of the comparably-sized Priestley. It is named after the inve ...

Chandler (crater) Chandler is a Lunar craters, lunar impact crater in the northern hemisphere, on the Moon's Far side (Moon), far side. It lies to the southeast of the large walled plain D'Alembert (crater), D'Alembert, and southeast of the slightly smaller Chernys ...

Chappell (crater) Chappell is a lunar impact crater on the far side of the Moon, in the northern hemisphere just to the north of the crater Debye The debye (symbol: D) (; ) is a CGS unit (a non- SI metric unit) of electric dipole momentTwo equal and opposite ch ...

* Chernyshev (crater) * Comrie (crater) *

Coulomb-Sarton Basin The Coulomb-Sarton Basin is a Pre-Nectarian impact basin on the far side of the moon. It is named after the crater Coulomb northeast of the center of the basin and the smaller crater Sarton just south of the center. The basin is not obvious o ...

* Crookes (crater) *

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 t ...

* Davisson (crater) *

Delporte (crater) Delporte is a lunar impact crater on the far side of the Moon. It overlies part of the northwestern rim of the huge walled plain Fermi, and the crater Litke is nearly attached to the southeastern rim. The crater is named after Eugène Joseph De ...

Dyson (crater) Dyson is a lunar impact crater, 63 kilometers in diameter, that lies on the 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, and east of van't Hoff. The mos ...

* 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 is the fifth largest satellite in the Solar System and the largest and most massive re ...

Esnault-Pelterie (crater) Esnault-Pelterie is a lunar impact crater on the far side of the Moon, named after French rocketry and astronautics pioneer Robert Esnault-Pelterie. It is located in the northern hemisphere, to the south of the crater Carnot. Esnault-Pelterie o ...

* 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) Fowler is a large lunar impact crater that lies in the northern hemisphere on the Moon's far side. It lies to the south-southwest of the crater Esnault-Pelterie, and north of Gadomski. Overlying the eastern rim and intruding into the interior is ...

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 eject ...

* Gerasimovich (crater) *

Gullstrand (crater) Gullstrand is a lunar impact crater that lies on the northern hemisphere on the Moon's far side. About one crater diameter to the southeast is the larger crater Perrine. To the west-southwest is Quetelet. This crater has a circular rim that ...

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 c ...

Hegu (crater) Hegu is a lunar impact crater that is located within Von Kármán crater on the far side of the Moon. The crater is located south of the landing site of the Chinese Chang'e 4 lander. The crater's name was approved by the IAU on 4 February 2019 ...

Hertzsprung (crater) Hertzsprung is an enormous lunar impact crater, or impact basin, that is located on the far side of the Moon, beyond the western limb. In dimension, this formation is larger than several of the lunar mare areas on the near side. It lies in the nort ...

* H. G. Wells (crater) * Hippocrates (lunar crater) * Houzeau (crater) *

Icarus (crater) Icarus is a lunar impact crater that lies on the Moon's far side. It is located to the west of the huge walled plain Korolev, and less than two crater diameters to the east of the crater Daedalus. To the south of Icarus is the smaller Amici. ...

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 th ...

* Izsak (crater) *

Jenner (crater) Jenner is a lunar crater that is located within the Mare Australe. It lies just past the southeastern limb, on the far side of the Moon, and can be viewed from the Earth during periods of favorable libration and lighting. Nearly attached to ...

Kamerlingh Onnes (crater) Kamerlingh Onnes is a lunar impact crater on the far side of the Moon. It lies less than a crater diameter to the north-northwest of the crater Kolhörster. North of Kamerlingh Onnes lies Shternberg and to the northwest is Weyl. This is a worn ...

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

Klute (crater) Klute is a crater on the Moon's far side. It lies to the southeast of the larger walled plain Fowler, and east of the crater Gadomski. Klute is a heavily worn crater with multiple smaller craters along the outer rim. The satellite crater Klu ...

Kolhörster (crater) Kolhörster is a lunar impact crater that is located on the moon's far side. It lies about a crater-diameter to the south-southeast of the crater Kamerlingh Onnes, and to the northeast of the crater Michelson. To the south of Kolhörster is an a ...

* Komarov (crater) * Korolev (lunar crater) * Kovalevskaya (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. Th ...

Kulik (crater) Kulik is a lunar impact crater that lies on the northern hemisphere of the Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent ...

Lamb (crater) Lamb is a lunar crater that lies beyond the southeastern limb on the Moon's far side. It is located in an irregular lunar mare region named Mare Australe, just to the east of the crater Jenner. This crater has a slender inner wall and an interi ...

* 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. Attached to the northeastern rim of Lander is Volkov J, which is joined with Volkov to the north. Just to t ...

* Langevin (crater) * Lebedev (crater) *

Leibnitz (crater) Leibnitz is a huge lunar impact crater that is located in the southern hemisphere on the far side of the Moon. This formation is the same size as Clavius on the near side. It is located to the east-southeast of Mare Ingenii, and is joined to the n ...

* Lucretius (crater) *

Lunar south pole The lunar south pole is the southernmost point on the Moon, at 90°S. It is of special interest to scientists because of the occurrence of water ice in permanently shadowed areas around it. The lunar south pole region features craters that ar ...

Maksutov (crater) Maksutov is a crater on the far side of the Moon. It is located just to the south-southwest of the larger walled plain Oppenheimer. To the southwest lies the crater Nishina, and to the west-northwest is the merged crater pairing of Davisson and ...

* McKellar (crater) *

Mare Australe Mare Australe (Latin ''austrāle'' the "Southern Sea") is a lunar mare located in the southeastern hemisphere of the Moon. It is 997 kilometers in diameter, overlapping the near and far sides of the Moon. Smooth, dark volcanic basalt lines the ...

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 ju ...

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 Ingenii (Latin ''ingeniī'', the "Sea of Cleverness") is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin, which is of the Pre-Nectarian epoch, which lies in turn in the outer part of the old ...

Mare Moscoviense Mare Moscoviense ( ; ) is a lunar mare that sits in the Moscoviense basin. It is one of the very few maria on the far side of the Moon. Like Mare Marginis, this mare appears to be fairly thin. However, it is clearly centered within a large impact ...

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 Schus ...

Michelson (crater) Michelson is a crater on the far side of the Moon. It lies along the northeastern outer rim of the huge walled plain Hertzsprung, and to the southwest of the crater Kolhörster. This is a heavily eroded crater formation with multiple impacts ...

Montes Cordillera Montes Cordillera is a mountain range on the Moon. This feature forms the outer wall of peaks that surround the Mare Orientale impact basin, the inner ring being formed by the Montes Rook. The center of the range is located at selenographic coord ...

Montes Rook Montes Rook is a ring-shaped mountain range that lies along the western limb of the Moon, crossing over to the far side. It completely encircles the Mare Orientale, and forms part of a massive impact basin feature. This range in turn is encircled ...

* Mons Tai *

Nicholson (lunar crater) Nicholson may refer to: People *Nicholson (name), a surname, and a list of people with the name Places Australia * Nicholson, Victoria * Nicholson, Queensland * Nicholson County, New South Wales * Nicholson River (disambiguation) * Nicholson ...

* 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 th ...

* Oppenheimer (crater) * Oresme (crater) *

Pannekoek (crater) Pannekoek is a lunar impact crater that is situated on the far side of the Moon, and cannot be seen directly from the Earth. The crater lies along the northern edge of the slightly larger Dellinger, and their common border forms an area of une ...

Paraskevopoulos (crater) Paraskevopoulos is an old lunar impact crater that is located on the far side of the Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to it ...

Parenago (crater) Parenago is an impact crater on the Moon's far side ''The Far Side'' is a single-panel comic created by Gary Larson and syndicated by Chronicle Features and then Universal Press Syndicate, which ran from December 31, 1979, to January 1, 19 ...

Patsaev (crater) Patsaev is a lunar impact crater that lies on the far side of the Moon, to the northeast of the prominent crater Tsiolkovskiy. To the northwest is the smaller crater Lander. This is a heavily damaged crater that now appears as little more than a ...

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) Pogson is a Lunar craters, lunar impact crater on the Moon's Far side (Moon), far side, behind the southeastern limb. It is located midway between the flooded crater Lebedev (crater), Lebedev to the southwest and Bjerknes (lunar crater), Bjerknes ...

* Priestley (lunar crater) *

Quetelet (crater) Quetelet is a Lunar craters, lunar impact crater, approximately 55 kilometers in diameter, that lies in the Moon's northern sphere, hemisphere, on the Far side (Moon), far side from the Earth. It lies to the southeast of the crater Schlesinger (c ...

Rowland (crater) Rowland is a large lunar impact crater that is located in the northern part of the Moon, on the far side from the Earth. This is an old, worn formation that is overlain by a number of smaller craters. The most notable of these is Rowland Y, which ...

Sarton (crater) Sarton is a Lunar craters, lunar impact crater that lies beyond the northwestern limb of the Moon, on the Far side (Moon), far side from the Earth. It is located to the southwest of the crater Coulomb (crater), Coulomb, to the north of the walled ...

Schlesinger (crater) Schlesinger is a lunar impact crater on the far side of the Moon. The crater Esnault-Pelterie overlies the western part of the rim and the outer rampart of that crater has covered about half the interior floor, leaving a crescent-shaped feature ...

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 vie ...

Shternberg (crater) Shternberg is an eroded lunar impact crater on the Moon's far side. It lies just to the west-northwest of the crater Ohm, and is completely covered by higher-albedo material from the ray system that surrounds Ohm. To the west-southwest of Shtern ...

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 libratio ...

Sniadecki (crater) Sniadecki is a lunar impact crater on the far side of the Moon. This is a circular, bowl-shaped feature that is not overlain by any significant impacts. However the larger satellite crater Sniadecki Q is attached to the southwestern outer rim a ...

Sommerfeld (crater) Sommerfeld is a large lunar impact crater that is located in the far northern latitudes of the Moon. It lies on the far side, and can only be viewed from orbit. To the south of Sommerfeld is Rowland, a crater about the same size as Sommerfeld. S ...

* Statio Tianhe *

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 Stebbin ...

* Stoletov (crater) *

Sverdrup (crater) Sverdrup is a lunar impact crater that is located about one crater diameter from the southern pole of the Moon. It lies on the far side of the Moon with respect to the Earth, in an area of the surface that is only illuminated by very oblique l ...

Tianjin (crater) Tianjin is a lunar impact crater that is located within Von Kármán crater on the far side of the Moon. The crater is located northeast of the landing site of the Chinese Chang'e 4 lander. The crater's name was approved by the IAU on 4 Februa ...

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) *

Tsinger (crater) Tsinger is a lunar impact crater that is located in the northern latitudes of the Moon's far side ''The Far Side'' is a single-panel comic created by Gary Larson and syndicated by Chronicle Features and then Universal Press Syndicate, which ...

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) * Vallis Bouvard * Vallis Inghirami *

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 lies ...

* Van der Waals (crater) *

Vavilov (crater) Vavilov is a prominent impact crater that is located to the west of the walled plain Hertzsprung. It is located on the far side of the Moon and cannot be viewed directly from the Earth. About a crater diameter to the northwest is the smaller Cha ...

* Vertregt (crater) * Volkov (crater) *

Von Kármán (lunar crater) Von Kármán is a large lunar impact crater that is located in the southern hemisphere on the far side of the Moon. The crater is about in diameter and lies within an immense impact crater known as the South Pole–Aitken basin of roughly i ...

Von Zeipel (crater) Von Zeipel is a lunar impact crater on the Moon's far side. It partly overlies the eastern rim of the larger crater Fowler, and intrudes into the interior floor. To the north of Von Zeipel is the crater Esnault-Pelterie, and due south lies Klut ...

* 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 southe ...

* Yamamoto (crater) *

Zhinyu (crater) Zhinyu is a lunar impact crater that is located within Von Kármán crater on the far side of the Moon. The crater is located west of the landing site of the Chinese Chang'e 4 lander. The crater's name was approved by the IAU on 4 February 2 ...

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 Lunar science Hemispheres of Moon