544 relations: A True Story, Ablation, Accretion disk, Advances in Space Research, Aether (classical element), Age of the Earth, Albedo, Altimeter, Aluminium oxide, American Philosophical Society, Anaxagoras, Ancient Greece, Ancient Greek, Ancient Greek art, Angular diameter, Angular momentum, Annals of the New York Academy of Sciences, Annual Review of Earth and Planetary Sciences, Anorthosite, Antipodes, Apollo 11, Apollo 12, Apollo 13, Apollo 14, Apollo 15, Apollo 16, Apollo 17, Apollo 8, Apollo Lunar Surface Experiments Package, Apollo program, Apollo TV camera, Apparent magnitude, Applied Optics, Apsis, Archimedes, Arctic, Arecibo Observatory, Ares (rocket), Argon, Aristarchus (crater), Aristarchus of Samos, Aristotelian physics, Aristotle, Artemis, Aryabhata, Aryabhatiya, Asphalt, Asphalt concrete, Associated Press, Astrogeology Research Program, ..., Astronaut, Astronomical object, Astronomical seeing, Astronomy & Astrophysics, Astrophysics and Space Science, Atmosphere, Atmosphere (unit), Atmosphere of Earth, Atmospheric entry, Atomic clock, Audi, Aviation Week, Axial tilt, Babylonian astronomy, Bad Astronomy, Bar (unit), Barry Karr, Barycenter, Basalt, Birkhäuser, Byzantium, Cabeus (crater), Calcium oxide, California Institute of Technology, Cambridge University Press, Camden House Publishing, Carbon, Carbon nanotube, Cassini's laws, Celestial equator, Centrifugal force, Cf., Chandrayaan-1, Chandrayaan-2, Chang'e 1, Chang'e 2, Chang'e 3, Chang'e 4, Chang'e 5, Charles Scribner's Sons, Charon (moon), Chinese astronomy, Chinese Lunar Exploration Program, Cirrostratus cloud, Claimed moons of Earth, Classical mythology, Clementine (spacecraft), CNSNews.com, Co-orbital configuration, Cold War, Colonization of the Moon, Color constancy, Comet, Comminution, Committee for Skeptical Inquiry, Common heritage of mankind, Compatibility (geochemistry), Constellation program, Coordinated Universal Time, Copernicus (lunar crater), Corona, Corona (optical phenomenon), Crater counting, Crater of eternal darkness, Crescent, Crust (geology), Culmination, Cumulate rock, Current Biology, Current Science, Cynthia, Declination, Density, Diana (mythology), Diffuse reflection, Dipole, Discovery Channel, Dissipation, Doppler effect, Dwarf planet, Earth, Earth and Planetary Science Letters, Earth radius, Earth tide, Earth's magnetic field, Earth, Moon, and Planets, Earthrise, Eclipse, Ecliptic, Ejecta blanket, Elongation (astronomy), Encyclopædia Britannica, English language, Epoxy, Equator, European Space Agency, Exosphere, Exploration of the Moon, Extraterrestrial real estate, Far side of the Moon, Far Ultraviolet Camera/Spectrograph, Fault scarp, Feasibility study, Fobos-Grunt, Fractional crystallization (geology), Francesco Maria Grimaldi, Friction, Full moon, G-force, Galileo Galilei, Geminids, Geochemistry, Geologic province, Geology of the Moon, Geophysical Research Letters, George W. Bush, Georgia State University, Geoscientist (magazine), Germanic calendar, Germanic languages, Germanic peoples, Giant-impact hypothesis, Giovanni Battista Riccioli, Goddard Space Flight Center, Google, Google Lunar X Prize, GRAIL, Gravitational field, Grove Karl Gilbert, Gunpowder, Halo (optical phenomenon), Han dynasty, HarperCollins, Hecate, Helios, Helium, Helium-4, Hermite (crater), High-definition video, History of Earth, Hiten, Horizontal coordinate system, Houston, Human spaceflight, Hydrogen, Hydroxy group, Ibn al-Haytham, Icarus (journal), Ice crystals, Ideal gas law, Imbrian, Impact crater, Impact gardening, Ina (crater), Inanna, India, Indian astronomy, Indian Space Research Organisation, Inertia, Infrared telescope, Internal structure of the Moon, International Astronautical Federation, International Astronomical Union, Io (moon), Ion thruster, Ionic liquid, Iron(II) oxide, Irregular mare patch, Islamic calendar, Isotope, Isotopes of polonium, JAXA, Jet Propulsion Laboratory, Jing Fang, Joe Nickell, Joel Spira (businessman), Johann Heinrich von Mädler, John F. Kennedy, John Walker (programmer), John Wiley & Sons, Journal of Geophysical Research, Jupiter, Kelvin, Kinetic energy, Knowth, KREEP, Lacus Felicitatis, LADEE, Lagrangian point, Lander (spacecraft), Late Heavy Bombardment, Latin, Latitude, LCROSS, Leap second, Leonardo (journal), Libration, Lidar, Limb darkening, List of Apollo astronauts, List of Apollo missions, List of largest craters in the Solar System, List of lunar deities, List of lunar features, List of natural satellites, Lucian, Luna 1, Luna 10, Luna 16, Luna 2, Luna 20, Luna 24, Luna 3, Luna 9, Luna programme, Luna-Glob, Lunar and Planetary Institute, Lunar and Planetary Science Conference, Lunar basalt 70017, Lunar calendar, Lunar day, Lunar distance (astronomy), Lunar dome, Lunar eclipse, Lunar effect, Lunar Flag Assembly, Lunar geologic timescale, Lunar Laser Ranging experiment, Lunar magma ocean, Lunar mare, Lunar node, Lunar north pole, Lunar orbit, Lunar Orbiter program, Lunar phase, Lunar Prospector, Lunar Reconnaissance Orbiter, Lunar rover, Lunar soil, Lunar south pole, Lunar standstill, Lunar water, Lunatic, Lunex Project, Lunisolar calendar, Lunokhod 1, Lunokhod 2, Lunokhod programme, Mafic, Magnesium, Magnesium oxide, Magnetic field, Magnetometer, Man in the Moon, Mantle (geology), March equinox, Mare Crisium, Mare Imbrium, Mare Orientale, Mare Serenitatis, Mare Smythii, Mars, Marshall Space Flight Center, Mass concentration (astronomy), Melt inclusions, Menelaus, Mercury (planet), Meteor shower, Meteoritical Society, Microsecond, Middle Ages, Minute and second of arc, MIT Press, Moon, Moon illusion, Moon in fiction, Moon landing, Moon Mineralogy Mapper, Moon rabbit, Moon rock, Moon Treaty, Moonlight, MSNBC, Muhammad, Multispectral image, Naked eye, NASA, National Geographic, National Space Science Data Center, Natural satellite, Nature (journal), Nature Geoscience, Near side of the Moon, Near-Earth object, Nectarian, Neil Armstrong, Neon, New moon, New Scientist, NHK, Nitrogen, Nokia, North America, North Pole, Northern Hemisphere, Occultation, Oceanus Procellarum, Ogg, Old English, Olivine, Omicron Centaurids, On the Heavens, On the Sizes and Distances (Aristarchus), Opposition surge, Orbit, Orbit of the Moon, Orbital period, Orbital plane (astronomy), Order of magnitude, Origin of the Moon, Orion (spacecraft), Outer Space Treaty, Outgassing, Oxford English Dictionary, Oxford University Press, Oxygen, Palgrave Macmillan, Parts-per notation, Pascal (unit), Patrick Moore, Peak of eternal light, Peary (crater), Pergamon Press, Perturbation (astronomy), Phil Plait, Philosophical Transactions of the Royal Society A, Photodissociation, Plagioclase, Planet, Planetary and Space Science, Planetary core, Planetary differentiation, Planetary geology, Planets in astrology, Planetshine, Pliny the Elder, Pluto, Polar night, Popular Astronomy (US magazine), Popular Science, Potassium, Precession, Precipitation (chemistry), Primary (astronomy), Project Horizon, Propellant depot, Proto-Germanic language, Proto-Indo-European language, Proto-Indo-European religion, Psychological Bulletin, Psychological Reports, Ptolemy, Pyroxene, Qi, Quadrantids, Quake (natural phenomenon), Quasi-satellite, Radio telescope, Radioactive decay, Radon, Ranger program, Red giant, Reflectance, Regolith, Retroreflector, Reviews in Mineralogy and Geochemistry, RIA Novosti, Richard A. 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A True Story (Ἀληθῆ διηγήματα, Alēthē diēgēmata; or) is a novel written in the second century AD by Lucian of Samosata, a Greek-speaking author of Syrian descent.
Ablation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes.
An accretion disk is a structure (often a circumstellar disk) formed by diffused material in orbital motion around a massive central body.
Advances in Space Research (ASR) is a peer-reviewed scientific journal that is published 27 times per year by Elsevier.
According to ancient and medieval science, aether (αἰθήρ aithēr), also spelled æther or ether and also called quintessence, is the material that fills the region of the universe above the terrestrial sphere.
The age of the Earth is 4.54 ± 0.05 billion years This age may represent the age of the Earth’s accretion, of core formation, or of the material from which the Earth formed.
Albedo (albedo, meaning "whiteness") is the measure of the diffuse reflection of solar radiation out of the total solar radiation received by an astronomical body (e.g. a planet like Earth).
An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level.
Aluminium oxide (British English) or aluminum oxide (American English) is a chemical compound of aluminium and oxygen with the chemical formula 23.
The American Philosophical Society (APS), founded in 1743 and located in Philadelphia, is an eminent scholarly organization of international reputation that promotes useful knowledge in the sciences and humanities through excellence in scholarly research, professional meetings, publications, library resources, and community outreach.
Anaxagoras (Ἀναξαγόρας, Anaxagoras, "lord of the assembly"; BC) was a Pre-Socratic Greek philosopher.
Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 13th–9th centuries BC to the end of antiquity (AD 600).
The Ancient Greek language includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD.
Ancient Greek art stands out among that of other ancient cultures for its development of naturalistic but idealized depictions of the human body, in which largely nude male figures were generally the focus of innovation.
The angular diameter, angular size, apparent diameter, or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view.
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational equivalent of linear momentum.
The Annals of the New York Academy of Sciences is an academic journal published by Wiley-Blackwell on behalf of the New York Academy of Sciences.
Annual Review of Earth and Planetary Sciences is an annual peer-reviewed scientific journal published by Annual Reviews, which broadly covers Earth and planetary sciences, including geology, atmospheric sciences, climate, geophysics, environmental science, geological hazards, geodynamics, planet formation, and solar system origins.
Anorthosite is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%).
In geography, the antipode of any spot on Earth is the point on Earth's surface diametrically opposite to it; the antipodes of a region similarly represent the area opposite it.
Apollo 11 was the spaceflight that landed the first two humans on the Moon.
Apollo 12 was the sixth manned flight in the United States Apollo program and the second to land on the Moon.
Apollo 13 was the seventh manned mission in the Apollo space program and the third intended to land on the Moon.
Apollo 14 was the eighth manned mission in the United States Apollo program, and the third to land on the Moon.
Apollo 15 was the ninth manned mission in the United States' Apollo program, the fourth to land on the Moon, and the eighth successful manned mission.
Apollo 16 was the tenth manned mission in the United States Apollo space program, the fifth and penultimate to land on the Moon and the first to land in the lunar highlands.
Apollo 17 was the final mission of NASA's Apollo program.
Apollo 8, the second manned spaceflight mission in the United States Apollo space program, was launched on December 21, 1968, and became the first manned spacecraft to leave Earth orbit, reach the Earth's Moon, orbit it and return safely to Earth.
The Apollo Lunar Surface Experiments Package (ALSEP) comprised a set of scientific instruments placed by the astronauts at the landing site of each of the five Apollo missions to land on the Moon following Apollo 11 (Apollos 12, 14, 15, 16, and 17).
The Apollo program, also known as Project Apollo, was the third United States human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), which accomplished landing the first humans on the Moon from 1969 to 1972.
The Apollo TV Camera refers to several television cameras used in the Apollo program's space missions, and on the later Skylab and Apollo-Soyuz Test Project missions, in the late 1960s and 1970s.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
Applied Optics is a peer-reviewed scientific journal published by The Optical Society three times a month.
An apsis (ἁψίς; plural apsides, Greek: ἁψῖδες) is an extreme point in the orbit of an object.
Archimedes of Syracuse (Ἀρχιμήδης) was a Greek mathematician, physicist, engineer, inventor, and astronomer.
The Arctic is a polar region located at the northernmost part of Earth.
The Arecibo Observatory is a radio telescope in the municipality of Arecibo, Puerto Rico.
In terms of rocketry, Ares could mean.
Argon is a chemical element with symbol Ar and atomic number 18.
Aristarchus, named after the Greek astronomer Aristarchus of Samos, is a prominent lunar impact crater that lies in the northwest part of the Moon's near side.
Aristarchus of Samos (Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios; c. 310 – c. 230 BC) was an ancient Greek astronomer and mathematician who presented the first known model that placed the Sun at the center of the known universe with the Earth revolving around it (see Solar system).
Aristotelian physics is a form of natural science described in the works of the Greek philosopher Aristotle (384–).
Aristotle (Ἀριστοτέλης Aristotélēs,; 384–322 BC) was an ancient Greek philosopher and scientist born in the city of Stagira, Chalkidiki, in the north of Classical Greece.
Artemis (Ἄρτεμις Artemis) was one of the most widely venerated of the Ancient Greek deities.
Aryabhata (IAST) or Aryabhata I (476–550 CE) was the first of the major mathematician-astronomers from the classical age of Indian mathematics and Indian astronomy.
Aryabhatiya (IAST) or Aryabhatiyam, a Sanskrit astronomical treatise, is the magnum opus and only known surviving work of the 5th century Indian mathematician Aryabhata.
Asphalt, also known as bitumen, is a sticky, black, and highly viscous liquid or semi-solid form of petroleum.
Asphalt concrete (commonly called asphalt, blacktop, or pavement in North America, and tarmac, bitumen macadam or rolled asphalt in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface roads, parking lots, airports, as well as the core of embankment dams.
The Associated Press (AP) is a U.S.-based not-for-profit news agency headquartered in New York City.
The Astrogeology Research Program is a program of the United States Geological Survey concerned with the study of planetary geology and planetary cartography.
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
Astronomical seeing is the blurring and twinkling of astronomical objects like stars due to turbulent mixing in the Earth's atmosphere, causing variations of the optical refractive index.
Astronomy & Astrophysics is a peer-reviewed scientific journal covering theoretical, observational, and instrumental astronomy and astrophysics.
Astrophysics and Space Science is a bimonthly peer-reviewed scientific journal covering astronomy, astrophysics, and space science and astrophysical aspects of astrobiology.
An atmosphere is a layer or a set of layers of gases surrounding a planet or other material body, that is held in place by the gravity of that body.
The standard atmosphere (symbol: atm) is a unit of pressure defined as.
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet or natural satellite.
An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.
Audi AG is a German automobile manufacturer that designs, engineers, produces, markets and distributes luxury vehicles.
The Aviation Week Network is a New-York based B2B publishing and event production company.
In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, or, equivalently, the angle between its equatorial plane and orbital plane.
The history of astronomy in Mesopotamia, and the world, begins with the Sumerians who developed the earliest writing system—known as cuneiform—around 3500–3200 BC.
Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing "Hoax" is a non-fiction book by the American astronomer Phil Plait, also known as "the Bad Astronomer".
The bar is a metric unit of pressure, but is not approved as part of the International System of Units (SI).
Barry Karr is the Executive Director of the Committee for Skeptical Inquiry.
The barycenter (or barycentre; from the Ancient Greek βαρύς heavy + κέντρον centre) is the center of mass of two or more bodies that are orbiting each other, which is the point around which they both orbit.
Basalt is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon.
Birkhäuser is a former Swiss publisher founded in 1879 by Emil Birkhäuser.
Byzantium or Byzantion (Ancient Greek: Βυζάντιον, Byzántion) was an ancient Greek colony in early antiquity that later became Constantinople, and later Istanbul.
Cabeus is a lunar impact crater that is located about from the south pole of the Moon.
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound.
The California Institute of Technology (abbreviated Caltech)The university itself only spells its short form as "Caltech"; other spellings such as.
Cambridge University Press (CUP) is the publishing business of the University of Cambridge.
Camden House, Inc. was founded in 1979 by professors James Hardin and Gunther Holst with the purpose of publishing scholarly books in the field of German literature, Austrian Literature, and German language culture.
Carbon (from carbo "coal") is a chemical element with symbol C and atomic number 6.
Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure.
Cassini's laws provide a compact description of the motion of the Moon.
The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) directed away from the axis of rotation that appears to act on all objects when viewed in a rotating frame of reference.
The abbreviation cf. (short for the confer/conferatur, both meaning "compare") is used in writing to refer the reader to other material to make a comparison with the topic being discussed.
Chandrayaan-1 (lit: Moon vehicle) was India's first lunar probe.
Chandrayaan-2 (lang; lit: Moon-vehicle) is India's second lunar exploration mission after Chandrayaan-1.
Chang'e 1 was an unmanned Chinese lunar-orbiting spacecraft, part of the first phase of the Chinese Lunar Exploration Program.
Chang'e 2 is a Chinese unmanned lunar probe that was launched on 1 October 2010.
Chang'e 3 is an unmanned lunar exploration mission operated by the China National Space Administration (CNSA), incorporating a robotic lander and China's first lunar rover.
Chang'e 4 is a planned Chinese lunar exploration mission, to be launched in December 2018, that will incorporate an orbiter, a robotic lander and rover.
Chang'e 5 is an unmanned Chinese lunar exploration mission currently under development, forecast for a Moon landing in 2019 after being postponed by the failure in 2017 of the Long March 5 launch vehicle.
Charles Scribner's Sons, or simply Scribner's or Scribner, is an American publisher based in New York City, known for publishing American authors including Ernest Hemingway, F. Scott Fitzgerald, Kurt Vonnegut, Marjorie Kinnan Rawlings, Stephen King, Robert A. Heinlein, Thomas Wolfe, George Santayana, John Clellon Holmes, Don DeLillo, and Edith Wharton.
Charon, also known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto.
Astronomy in China has a long history, beginning from the Shang Dynasty (Chinese Bronze Age).
The Chinese Lunar Exploration Program (CLEP), also known as the Chang'e program after the Chinese moon goddess Chang'e, is an ongoing series of robotic Moon missions by the China National Space Administration (CNSA).
Cirrostratus is a high-level, very thin, generally uniform stratiform genus-type of cloud, composed of ice-crystals.
Claims of the existence of other moons of Earth—that is, of one or more natural satellites other than the Moon that orbit Earth—have existed for some time.
Classical Greco-Roman mythology, Greek and Roman mythology or Greco-Roman mythology is both the body of and the study of myths from the ancient Greeks and Romans as they are used or transformed by cultural reception.
Clementine (officially called the Deep Space Program Science Experiment (DSPSE)) was a joint space project between the Ballistic Missile Defense Organization (BMDO, previously the Strategic Defense Initiative Organization, or SDIO) and NASA.
CNSNews.com (formerly known as Cybercast News Service) is a politically conservative American news and commentary website founded by L. Brent Bozell III and owned by Media Research Center, Bozell's Reston, Virginia-based organization.
In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects (such as asteroids, moons, or planets) orbiting at the same, or very similar, distance from their primary, i.e. they are in a 1:1 mean-motion resonance.
The Cold War was a state of geopolitical tension after World War II between powers in the Eastern Bloc (the Soviet Union and its satellite states) and powers in the Western Bloc (the United States, its NATO allies and others).
The colonization of the Moon is a proposed establishment of permanent human communities or robotic industries on the Moon.
Color constancy is an example of subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions.
A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing.
Comminution is the reduction of solid materials from one average particle size to a smaller average particle size, by crushing, grinding, cutting, vibrating, or other processes.
The Committee for Skeptical Inquiry (CSI), formerly known as the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP), is a program within the transnational American non-profit educational organization Center for Inquiry (CFI), which seeks to "promote scientific inquiry, critical investigation, and the use of reason in examining controversial and extraordinary claims." Paul Kurtz proposed the establishment of CSICOP in 1976 as an independent non-profit organization (before merging with CFI as one of its programs in 2015), to counter what he regarded as an uncritical acceptance of, and support for, paranormal claims by both the media and society in general.
Common heritage of mankind (also termed the common heritage of humanity, common heritage of humankind or common heritage principle) is a principle of international law which holds that defined territorial areas and elements of humanity's common heritage (cultural and natural) should be held in trust for future generations and be protected from exploitation by individual nation states or corporations.
In geochemistry, compatibility is a measure of how readily a particular trace element substitutes for a major element within a mineral.
The Constellation Program (abbreviated CxP) is a cancelled manned spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009.
Copernicus is a lunar impact crater named after the astronomer Nicolaus Copernicus, located in eastern Oceanus Procellarum.
A corona (Latin, 'crown') is an aura of plasma that surrounds the Sun and other stars.
In meteorology, a corona (plural coronae) is an optical phenomenon produced by the diffraction of sunlight or moonlight (or, occasionally, bright starlight or planetlight) by individual small water droplets and sometimes tiny ice crystals of a cloud or on a foggy glass surface.
Crater counting is a method for estimating the age of a planet's surface.
A crater of eternal darkness is a point on a body within the Solar System which is always in darkness.
A crescent shape (British English also) is a symbol or emblem used to represent the lunar phase in the first quarter (the "sickle moon"), or by extension a symbol representing the Moon itself.
In geology, the crust is the outermost solid shell of a rocky planet, dwarf planet, or natural satellite.
In astronomy, the culmination of a planet, star, or constellation is its transit over an observer's meridian.
Cumulate rocks are igneous rocks formed by the accumulation of crystals from a magma either by settling or floating.
Current Biology is a scientific journal that covers all areas of biology, especially molecular biology, cell biology, genetics, neurobiology, ecology and evolutionary biology.
Current Science is an English-language peer-reviewed multidisciplinary scientific journal.
Cynthia is a feminine given name of Greek origin: Κυνθία, Kynthía, "from Mount Cynthus" on Delos island.
In astronomy, declination (abbreviated dec; symbol δ) is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle.
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.
Diana (Classical Latin) was the goddess of the hunt, the moon, and nature in Roman mythology, associated with wild animals and woodland, and having the power to talk to and control animals.
Diffuse reflection is the reflection of light or other waves or particles from a surface such that a ray incident on the surface is scattered at many angles rather than at just one angle as in the case of specular reflection.
In electromagnetism, there are two kinds of dipoles.
Discovery Channel (known as The Discovery Channel from 1985 to 1995, and often referred to as simply Discovery) is an American pay television channel that is the flagship television property of Discovery Inc., a publicly traded company run by CEO David Zaslav.
Dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems.
The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave in relation to observer who is moving relative to the wave source.
A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
Earth and Planetary Science Letters is a weekly peer-reviewed scientific journal covering research on physical, chemical and mechanical processes of the Earth and other planets, including extrasolar ones.
Earth radius is the approximate distance from Earth's center to its surface, about.
Earth tide (also known as solid Earth tide, crustal tide, body tide, bodily tide or land tide) is the displacement of the solid earth's surface caused by the gravity of the Moon and Sun.
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it meets the solar wind, a stream of charged particles emanating from the Sun.
Earth, Moon, and Planets is a peer-reviewed scientific journal, published approximately ten times per year by Springer Science+Business Media.
Earthrise is a photograph of the Earth and parts of the Moon's surface taken from lunar orbit by astronaut Bill Anders in 1968, during the Apollo 8 mission.
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.
The ecliptic is the circular path on the celestial sphere that the Sun follows over the course of a year; it is the basis of the ecliptic coordinate system.
An ejecta blanket is a generally symmetrical apron of ejecta that surrounds an impact crater; it is layered thickly at the crater’s rim and thin to discontinuous at the blanket’s outer edge.
In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point.
The Encyclopædia Britannica (Latin for "British Encyclopaedia"), published by Encyclopædia Britannica, Inc., is a general knowledge English-language encyclopaedia.
English is a West Germanic language that was first spoken in early medieval England and is now a global lingua franca.
Epoxy is either any of the basic components or the cured end products of epoxy resins, as well as a colloquial name for the epoxide functional group.
An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).
The European Space Agency (ESA; Agence spatiale européenne, ASE; Europäische Weltraumorganisation) is an intergovernmental organisation of 22 member states dedicated to the exploration of space.
The exosphere (ἔξω éxō "outside, external, beyond", σφαῖρα sphaĩra "sphere") is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is too low for them to behave as a gas by colliding with each other.
The physical exploration of the Moon began when Luna 2, a space probe launched by the Soviet Union, made an impact on the surface of the Moon on September 14, 1959.
Extraterrestrial real estate refers to claims of land ownership on other planets or natural satellites or parts of space by certain organizations and individuals.
The far side of the Moon (sometimes figuratively known as the dark side of the Moon) is the hemisphere of the Moon that always faces away from Earth.
The Far Ultraviolet Camera/Spectrograph (UVC) was one of the experiments deployed on the lunar surface by the Apollo 16 astronauts.
A fault scarp is a small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other.
Feasibility Study is an assessment of the practicality of a proposed project or system.
Fobos-Grunt or Phobos-Grunt (Фобос-Грунт, literally "Phobos-Ground") was an attempted Russian sample return mission to Phobos, one of the moons of Mars.
Fractional crystallization, or crystal fractionation, is one of the most important geochemical and physical processes operating within the Earth's crust and mantle.
Francesco Maria Grimaldi (2 April 1618 – 28 December 1663) was an Italian Jesuit priest, mathematician and physicist who taught at the Jesuit college in Bologna.
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective.
The gravitational force, or more commonly, g-force, is a measurement of the type of acceleration that causes a perception of weight.
Galileo Galilei (15 February 1564Drake (1978, p. 1). The date of Galileo's birth is given according to the Julian calendar, which was then in force throughout Christendom. In 1582 it was replaced in Italy and several other Catholic countries with the Gregorian calendar. Unless otherwise indicated, dates in this article are given according to the Gregorian calendar. – 8 January 1642) was an Italian polymath.
The Geminids are a meteor shower caused by the object 3200 Phaethon, which is thought to be a Palladian asteroid with a "rock comet" orbit.
Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans.
A geologic or geomorphic province is a spatial entity with common geologic or geomorphic attributes.
The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar science") is quite different from that of Earth.
Geophysical Research Letters is a biweekly peer-reviewed scientific journal of geoscience published by the American Geophysical Union that was established in 1974.
George Walker Bush (born July 6, 1946) is an American politician who served as the 43rd President of the United States from 2001 to 2009.
Georgia State University (commonly referred to as Georgia State, State, or GSU) is a public research university in downtown Atlanta, Georgia, United States.
Geoscientist is a monthly magazine produced for the Fellowship of the Geological Society of London.
The Germanic calendars were the regional calendars used amongst the early Germanic peoples, prior to the adoption of the Julian calendar in the Early Middle Ages.
The Germanic languages are a branch of the Indo-European language family spoken natively by a population of about 515 million people mainly in Europe, North America, Oceania, and Southern Africa.
The Germanic peoples (also called Teutonic, Suebian, or Gothic in older literature) are an Indo-European ethno-linguistic group of Northern European origin.
The giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact suggests that the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars, approximately 4.5 billion years ago, in the Hadean eon; about 20 to 100 million years after the solar system coalesced.
Giovanni Battista Riccioli (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order.
The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States.
Google LLC is an American multinational technology company that specializes in Internet-related services and products, which include online advertising technologies, search engine, cloud computing, software, and hardware.
The Google Lunar XPRIZE (GLXP), sometimes referred to as Moon 2.0, was a 2007–2018 inducement prize space competition organized by the X Prize Foundation, and sponsored by Google.
The Gravity Recovery and Interior Laboratory (GRAIL) was an American lunar science mission in NASA's Discovery Program which used high-quality gravitational field mapping of the Moon to determine its interior structure.
In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.
Grove Karl Gilbert (May 6, 1843 – May 1, 1918), known by the abbreviated name G. K. Gilbert in academic literature, was an American geologist.
Gunpowder, also known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive.
Halo (from Greek ἅλως, halōs) is the name for a family of optical phenomena produced by sunlight interacting with ice crystals suspended in the atmosphere.
The Han dynasty was the second imperial dynasty of China (206 BC–220 AD), preceded by the Qin dynasty (221–206 BC) and succeeded by the Three Kingdoms period (220–280 AD). Spanning over four centuries, the Han period is considered a golden age in Chinese history. To this day, China's majority ethnic group refers to themselves as the "Han Chinese" and the Chinese script is referred to as "Han characters". It was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han, and briefly interrupted by the Xin dynasty (9–23 AD) of the former regent Wang Mang. This interregnum separates the Han dynasty into two periods: the Western Han or Former Han (206 BC–9 AD) and the Eastern Han or Later Han (25–220 AD). The emperor was at the pinnacle of Han society. He presided over the Han government but shared power with both the nobility and appointed ministers who came largely from the scholarly gentry class. The Han Empire was divided into areas directly controlled by the central government using an innovation inherited from the Qin known as commanderies, and a number of semi-autonomous kingdoms. These kingdoms gradually lost all vestiges of their independence, particularly following the Rebellion of the Seven States. From the reign of Emperor Wu (r. 141–87 BC) onward, the Chinese court officially sponsored Confucianism in education and court politics, synthesized with the cosmology of later scholars such as Dong Zhongshu. This policy endured until the fall of the Qing dynasty in 1911 AD. The Han dynasty saw an age of economic prosperity and witnessed a significant growth of the money economy first established during the Zhou dynasty (c. 1050–256 BC). The coinage issued by the central government mint in 119 BC remained the standard coinage of China until the Tang dynasty (618–907 AD). The period saw a number of limited institutional innovations. To finance its military campaigns and the settlement of newly conquered frontier territories, the Han government nationalized the private salt and iron industries in 117 BC, but these government monopolies were repealed during the Eastern Han dynasty. Science and technology during the Han period saw significant advances, including the process of papermaking, the nautical steering ship rudder, the use of negative numbers in mathematics, the raised-relief map, the hydraulic-powered armillary sphere for astronomy, and a seismometer for measuring earthquakes employing an inverted pendulum. The Xiongnu, a nomadic steppe confederation, defeated the Han in 200 BC and forced the Han to submit as a de facto inferior partner, but continued their raids on the Han borders. Emperor Wu launched several military campaigns against them. The ultimate Han victory in these wars eventually forced the Xiongnu to accept vassal status as Han tributaries. These campaigns expanded Han sovereignty into the Tarim Basin of Central Asia, divided the Xiongnu into two separate confederations, and helped establish the vast trade network known as the Silk Road, which reached as far as the Mediterranean world. The territories north of Han's borders were quickly overrun by the nomadic Xianbei confederation. Emperor Wu also launched successful military expeditions in the south, annexing Nanyue in 111 BC and Dian in 109 BC, and in the Korean Peninsula where the Xuantu and Lelang Commanderies were established in 108 BC. After 92 AD, the palace eunuchs increasingly involved themselves in court politics, engaging in violent power struggles between the various consort clans of the empresses and empresses dowager, causing the Han's ultimate downfall. Imperial authority was also seriously challenged by large Daoist religious societies which instigated the Yellow Turban Rebellion and the Five Pecks of Rice Rebellion. Following the death of Emperor Ling (r. 168–189 AD), the palace eunuchs suffered wholesale massacre by military officers, allowing members of the aristocracy and military governors to become warlords and divide the empire. When Cao Pi, King of Wei, usurped the throne from Emperor Xian, the Han dynasty would eventually collapse and ceased to exist.
HarperCollins Publishers L.L.C. is one of the world's largest publishing companies and is one of the Big Five English-language publishing companies, alongside Hachette, Macmillan, Penguin Random House, and Simon & Schuster.
Hecate or Hekate (Ἑκάτη, Hekátē) is a goddess in ancient Greek religion and mythology, most often shown holding a pair of torches or a keyThe Running Maiden from Eleusis and the Early Classical Image of Hekate by Charles M. Edwards in the American Journal of Archaeology, Vol.
Helios (Ἥλιος Hēlios; Latinized as Helius; Ἠέλιος in Homeric Greek) is the god and personification of the Sun in Greek mythology.
Helium (from lit) is a chemical element with symbol He and atomic number 2.
Helium-4 is a non-radioactive isotope of the element helium.
laser altimeter Lunar Orbiter 4 image Hermite is a lunar impact crater located along the northern lunar limb, close to the north pole of the Moon.
High-definition video is video of higher resolution and quality than standard-definition.
The history of Earth concerns the development of planet Earth from its formation to the present day.
The Hiten Spacecraft (ひてん), given the English name Celestial Maiden and known before launch as MUSES-A (Mu Space Engineering Spacecraft A), part of the MUSES Program, was built by the Institute of Space and Astronautical Science of Japan and launched on January 24, 1990.
The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane.
Houston is the most populous city in the U.S. state of Texas and the fourth most populous city in the United States, with a census-estimated 2017 population of 2.312 million within a land area of.
Human spaceflight (also referred to as crewed spaceflight or manned spaceflight) is space travel with a crew or passengers aboard the spacecraft.
Hydrogen is a chemical element with symbol H and atomic number 1.
A hydroxy or hydroxyl group is the entity with the formula OH.
Hasan Ibn al-Haytham (Latinized Alhazen; full name أبو علي، الحسن بن الحسن بن الهيثم) was an Arab mathematician, astronomer, and physicist of the Islamic Golden Age.
Icarus is a scientific journal dedicated to the field of planetary science.
Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust.
The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas.
The Imbrian is a lunar geologic period divided into two epochs, the Early Imbrian and Late Imbrian.
An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body.
Impact gardening is the process by which impact events stir the outermost crusts of moons and other celestial objects with no atmospheres.
Ina is a peculiar small depression ("crater" in IAU nomenclature) on the Moon, in Lacus Felicitatis.
Inanna was the ancient Sumerian goddess of love, beauty, sex, desire, fertility, war, combat, justice, and political power.
India (IAST), also called the Republic of India (IAST), is a country in South Asia.
Indian astronomy has a long history stretching from pre-historic to modern times.
The Indian Space Research Organisation (ISRO) is the space agency of the Government of India headquartered in the city of Bangalore.
Inertia is the resistance of any physical object to any change in its position and state of motion.
An infrared telescope is a telescope that uses infrared light to detect celestial bodies.
Having a mean density of 3,346.4 kg/m³, the Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and planetary core.
The International Astronautical Federation (IAF) (Fédération internationale d'astronautique) is an international space advocacy organisation based in Paris, and founded in 1951 as a non-governmental organization to establish a dialogue between scientists around the world and to lay the information for international space cooperation.
The International Astronomical Union (IAU; Union astronomique internationale, UAI) is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy.
Io (Jupiter I) is the innermost of the four Galilean moons of the planet Jupiter.
An ion thruster or ion drive is a form of electric propulsion used for spacecraft propulsion.
An ionic liquid (IL) is a salt in the liquid state.
Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO.
An irregular mare patch also known as an IMP, is a smooth, rounded, slightly mounded area, generally about 500 meters wide, occurring in the lunar maria.
The Islamic, Muslim, or Hijri calendar (التقويم الهجري at-taqwīm al-hijrī) is a lunar calendar consisting of 12 months in a year of 354 or 355 days.
Isotopes are variants of a particular chemical element which differ in neutron number.
Polonium (84Po) has 33 isotopes, all of which are radioactive, with between 186 and 227 nucleons.
The is the Japanese national aerospace and space agency.
The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in Pasadena, California, United States, with large portions of the campus in La Cañada Flintridge, California.
Jing Fang (78–37 BC), born Li Fang (李房), courtesy name Junming (君明), was born in present-day 東郡頓丘 (Puyang, Henan) during the Han Dynasty (202 BC – 220 AD).
Joe Nickell (born December 1, 1944) is an American prominent skeptic and investigator of the paranormal.
Joel Solon Spira (March 1, 1927 – April 8, 2015) was an American inventor, entrepreneur, and business magnate.
Johann Heinrich von Mädler (May 29, 1794, Berlin – March 14, 1874, Hannover) was a German astronomer.
John Fitzgerald "Jack" Kennedy (May 29, 1917 – November 22, 1963), commonly referred to by his initials JFK, was an American politician who served as the 35th President of the United States from January 1961 until his assassination in November 1963.
John Walker is a computer programmer, author and co-founder of the computer-aided design software company Autodesk.
John Wiley & Sons, Inc., also referred to as Wiley, is a global publishing company that specializes in academic publishing.
The Journal of Geophysical Research is a peer-reviewed scientific journal.
Jupiter is the fifth planet from the Sun and the largest in the Solar System.
The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics.
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
Knowth (Cnóbha) is a Neolithic passage grave and an ancient monument of the World Heritage Site of Brú na Bóinne located 8.4 km west of Drogheda in Ireland's valley of the River Boyne.
KREEP, an acronym built from the letters K (the atomic symbol for potassium), REE (rare-earth elements) and P (for phosphorus), is a geochemical component of some lunar impact breccia and basaltic rocks.
Lacus Felicitatis (Latin for "Lake of Happiness") is a small patch of the lunar surface that has been inundated by flows of lava, leaving a level patch with a lower albedo than the surrounding ground.
The Lunar Atmosphere and Dust Environment Explorer (LADEE) was a NASA lunar exploration and technology demonstration mission.
In celestial mechanics, the Lagrangian points (also Lagrange points, L-points, or libration points) are positions in an orbital configuration of two large bodies, wherein a small object, affected only by the gravitational forces from the two larger objects, will maintain its position relative to them.
A lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body.
The Late Heavy Bombardment (abbreviated LHB and also known as the lunar cataclysm) is an event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean and Eoarchean eras on Earth.
Latin (Latin: lingua latīna) is a classical language belonging to the Italic branch of the Indo-European languages.
In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earth's surface.
The Lunar Crater Observation and Sensing Satellite (LCROSS) was a robotic spacecraft operated by NASA.
A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time as realized by UT1.
Leonardo® is a peer-reviewed academic journal published by the MIT Press covering the application of contemporary science and technology to the arts and music.
In astronomy, libration is a perceived oscillating motion of orbiting bodies relative to each other, notably including the motion of the Moon relative to Earth, or of trojan asteroids relative to planets.
Lidar (also called LIDAR, LiDAR, and LADAR) is a surveying method that measures distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor.
Limb darkening is an optical effect seen in stars (including the Sun), where the center part of the disk appears brighter than the edge or limb of the image.
Thirty-two astronauts were assigned to fly in the Apollo manned lunar landing program.
The Apollo program, also known as Project Apollo, was the third United States human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), which accomplished landing the first humans on the Moon from 1969 to 1972.
Following are the largest impact craters on various worlds of the Solar System.
In mythology, a lunar deity is a god or goddess associated with, or symbolic of the moon.
Several features cover the surface of the Moon.
The Solar System's planets and officially recognized dwarf planets are known to be orbited by 184 natural satellites, or moons.
Lucian of Samosata (125 AD – after 180 AD) was a Hellenized Syrian satirist and rhetorician who is best known for his characteristic tongue-in-cheek style, with which he frequently ridiculed superstition, religious practices, and belief in the paranormal.
Luna 1, also known as Mechta (Мечта, lit.: Dream), E-1 No.4 and First Lunar Rover, was the first spacecraft to reach the vicinity of the Earth's Moon, and the first spacecraft to be placed in heliocentric orbit.
Luna 10 (E-6S series) was a 1966 Soviet Luna program, robotic spacecraft mission, also called Lunik 10.
Luna 16, also known as Lunik 16, was an unmanned space mission, part of the Soviet Luna program.
Luna 2 (E-1A series) or Lunik 2 was the second of the Soviet Union's Luna programme spacecraft launched to the Moon.
Luna 20 was the second of three successful Soviet lunar sample return missions.
Luna 24 was an unmanned space mission of the Soviet Union's Luna programme.
Luna 3, or E-2A No.1 was a Soviet spacecraft launched in 1959 as part of the Luna programme.
Luna 9 (Луна-9), internal designation Ye-6 No.13, was an unmanned space mission of the Soviet Union's Luna programme.
The Luna programme (from the Russian word Луна "Luna" meaning "Lunar" or "Moon"), occasionally called Lunik or Lunnik by western media, was a series of robotic spacecraft missions sent to the Moon by the Soviet Union between 1959 and 1976.
Luna-Glob (Луна-Глоб, meaning Lunar sphere) is a Moon exploration programme by the Russian Federal Space Agency (Roscosmos) meant to progress toward the creation of a fully robotic lunar base.
The Lunar and Planetary Institute (LPI) is a scientific research institute dedicated to study of the solar system, its formation, evolution, and current state.
The Lunar and Planetary Science Conference (LPSC), jointly sponsored by the Lunar and Planetary Institute (LPI) and NASA Johnson Space Center (JSC), brings together international specialists in petrology, geochemistry, geophysics, geology, and astronomy to present the latest results of research in planetary science.
The Lunar basalt 70017 is a moon rock gathered in 1972 by astronauts Eugene Cernan and Harrison Schmitt on the Apollo 17 mission near their Apollo lunar lander from the valley of Taurus-Littrow on the moon and divided into 1.1 gram pieces.
A lunar calendar is a calendar based upon the monthly cycles of the Moon's phases (synodic months), in contrast to solar calendars, whose annual cycles are based only directly upon the solar year.
A lunar day is the period of time for Earth's Moon to complete one rotation on its axis with respect to the Sun.
Lunar distance (LD or \Delta_), also called Earth–Moon distance, Earth–Moon characteristic distance, or distance to the Moon, is a unit of measure in astronomy.
A lunar dome is a type of shield volcano that is found on the surface of the Earth's Moon.
A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow.
The term lunar effect refers to real or imaginary correlations between specific stages of the roughly 29.5-day lunar cycle and behavior and physiological changes in living beings on Earth, including humans.
The Lunar Flag Assembly (LFA) was a kit containing a flag of the United States designed to be planted by astronauts on the Moon during the Apollo program.
The lunar geological timescale (or selenological timescale) divides the history of Earth's Moon into five generally recognized periods: the Copernican, Eratosthenian, Imbrian (Late and Early epochs), Nectarian, and Pre-Nectarian.
The ongoing Lunar Laser Ranging experiment measures the distance between Earth and the Moon using laser ranging.
According to the giant impact hypothesis a large amount of energy was liberated in the formation of the Moon and it is inferred that as a result a large portion of the Moon was once completely molten, forming a lunar magma ocean.
The lunar maria (singular: mare) are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions.
The lunar nodes are the orbital nodes of the Moon, that is, the two points at which the orbit of the Moon crosses the ecliptic.
The lunar north pole is the point in the Northern Hemisphere of the Moon where the lunar axis of rotation meets its surface.
In astronomy, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon.
The Lunar Orbiter program was a series of five unmanned lunar orbiter missions launched by the United States from 1966 through 1967.
The lunar phase or phase of the Moon is the shape of the directly sunlit portion of the Moon as viewed from Earth.
Lunar Prospector was the third mission selected by NASA for full development and construction as part of the Discovery Program.
The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit.
A lunar rover or Moon rover is a space exploration vehicle (rover) designed to move across the surface of the Moon.
Lunar soil is the fine fraction of the regolith found on the surface of the Moon.
The lunar south pole is of special interest to scientists because of the postulated occurrence of water ice in permanently shadowed areas around it.
At a major lunar standstill, which takes place every 18.6 years, the Moon's range of declination, and consequently its range of azimuth at moonrise and moonset, reaches a maximum.
Lunar water is water that is present on the Moon.
Lunatic is an informal term referring to a person who is considered as mentally ill, dangerous, foolish or unpredictable, crazy, conditions once attributed to lunacy.
The Lunex Project was a US Air Force 1958 plan for a manned lunar landing prior to the Apollo Program.
A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year.
Lunokhod 1 (Луноход, moon walker in Russian; Аппарат 8ЕЛ № 203, vehicle 8ЕЛ№203) was the first of two unmanned lunar rovers landed on the Moon by the Soviet Union as part of its Lunokhod program.
Lunokhod 2 (Луноход-2, moon walker) was the second of two unmanned lunar rovers landed on the Moon by the Soviet Union as part of the Lunokhod programme.
Lunokhod (Луноход, "Moonwalker") was a series of Soviet robotic lunar rovers designed to land on the Moon between 1969 and 1977.
Mafic is an adjective describing a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and '''f'''err'''ic'''.
Magnesium is a chemical element with symbol Mg and atomic number 12.
Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide).
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.
A magnetometer is an instrument that measures magnetism—either the magnetization of a magnetic material like a ferromagnet, or the direction, strength, or relative change of a magnetic field at a particular location.
The Man in the Moon refers to any of several pareidolic images of a human face, head or body that certain traditions recognise in the disc of the full moon.
The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies.
The March equinox or Northward equinox is the equinox on the Earth when the subsolar point appears to leave the southern hemisphere and cross the celestial equator, heading northward as seen from Earth.
Mare Crisium (the "Sea of Crises") is a lunar mare located in the Moon's Crisium basin, just northeast of Mare Tranquillitatis.
Mare Imbrium (Latin for "Sea of Showers" or "Sea of Rains") is a vast lava plain within the Imbrium Basin on the Moon and is one of the larger craters in the Solar System.
Mare Orientale ("eastern sea" in Latin) is a lunar mare.
Mare Serenitatis ("Sea of Serenity") is a lunar mare located to the east of Mare Imbrium on the Moon.
Mare Smythii (Latin for "Sea of Smyth") is a lunar mare located along the equator on the easternmost edge of the lunar near side.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury.
The George C. Marshall Space Flight Center (MSFC), located in Huntsville, Alabama, is the U.S. government's civilian rocketry and spacecraft propulsion research center.
In astronomy and astrophysics, a mass concentration (or mascon) is a region of a planet or moon's crust that contains a large positive gravitational anomaly.
Melt inclusions are small parcels or "blobs" of melt(s) that are entrapped by crystals growing in the magmas and eventually forming igneous rocks.
In Greek mythology, Menelaus (Μενέλαος, Menelaos, from μένος "vigor, rage, power" and λαός "people," "wrath of the people") was a king of Mycenaean (pre-Dorian) Sparta, the husband of Helen of Troy, and the son of Atreus and Aerope.
Mercury is the smallest and innermost planet in the Solar System.
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky.
The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of the origin and history of the solar system.
A microsecond is an SI unit of time equal to one millionth (0.000001 or 10−6 or 1/1,000,000) of a second.
In the history of Europe, the Middle Ages (or Medieval Period) lasted from the 5th to the 15th century.
A minute of arc, arcminute (arcmin), arc minute, or minute arc is a unit of angular measurement equal to of one degree.
The MIT Press is a university press affiliated with the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts (United States).
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
The Moon illusion is an optical illusion which causes the Moon to appear larger near the horizon than it does higher up in the sky.
The Moon has been the subject of many works of art and literature and the inspiration for countless others.
A Moon landing is the arrival of a spacecraft on the surface of the Moon.
3 Home--> The Moon Mineralogy Mapper (M3) is one of two instruments that NASA contributed to India's first mission to the Moon, Chandrayaan-1, launched October 22, 2008.
The moon rabbit in folklore is a rabbit that lives on the Moon, based on pareidolia that identifies the markings of the Moon as a rabbit.
Moon rock or lunar rock is rock that is found on the Earth's moon, or lunar material collected during the course of human exploration of the Moon.
The Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, better known as the Moon Treaty or Moon Agreement, is a multilateral treaty that turns jurisdiction of all celestial bodies (including the orbits around such bodies) over to the international community.
Moonlight consists of mostly sunlight (with little earthlight) reflected from the parts of the Moon's surface where the Sun's light strikes.
MSNBC is an American news cable and satellite television network that provides news coverage and political commentary from NBC News on current events.
MuhammadFull name: Abū al-Qāsim Muḥammad ibn ʿAbd Allāh ibn ʿAbd al-Muṭṭalib ibn Hāšim (ابو القاسم محمد ابن عبد الله ابن عبد المطلب ابن هاشم, lit: Father of Qasim Muhammad son of Abd Allah son of Abdul-Muttalib son of Hashim) (مُحمّد;;Classical Arabic pronunciation Latinized as Mahometus c. 570 CE – 8 June 632 CE)Elizabeth Goldman (1995), p. 63, gives 8 June 632 CE, the dominant Islamic tradition.
A multispectral image is one that captures image data within specific wavelength ranges across the electromagnetic spectrum.
Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying or light-collecting optical instrument, such as a telescope or microscope.
The National Aeronautics and Space Administration (NASA) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.
National Geographic (formerly the National Geographic Magazine and branded also as NAT GEO or) is the official magazine of the National Geographic Society.
The National Space Science Data Center serves as the permanent archive for NASA space science mission data.
A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
Nature is a British multidisciplinary scientific journal, first published on 4 November 1869.
Nature Geoscience is a monthly peer-reviewed scientific journal published by the Nature Publishing Group.
The near side of the Moon is the lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the far side of the Moon.
A near-Earth object (NEO) is any small Solar System body whose orbit can bring it into proximity with Earth.
The Nectarian Period of the lunar geologic timescale runs from 3920 million years ago to 3850 million years ago.
Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aeronautical engineer who was the first person to walk on the Moon.
Neon is a chemical element with symbol Ne and atomic number 10.
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude.
New Scientist, first published on 22 November 1956, is a weekly, English-language magazine that covers all aspects of science and technology.
is Japan's national public broadcasting organization.
Nitrogen is a chemical element with symbol N and atomic number 7.
Nokia is a Finnish multinational telecommunications, information technology, and consumer electronics company, founded in 1865.
North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere; it is also considered by some to be a northern subcontinent of the Americas.
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is (subject to the caveats explained below) defined as the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface.
The Northern Hemisphere is the half of Earth that is north of the Equator.
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer.
Oceanus Procellarum (Latin for "Ocean of Storms") is a vast lunar mare on the western edge of the near side of the Moon.
Ogg is a free, open container format maintained by the Xiph.Org Foundation.
Old English (Ænglisc, Anglisc, Englisc), or Anglo-Saxon, is the earliest historical form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages.
The mineral olivine is a magnesium iron silicate with the formula (Mg2+, Fe2+)2SiO4.
The Omicron Centaurids meteor shower has a radiant which is in the constellation Centaurus which is visible from the southern hemisphere.
On the Heavens (Greek: Περὶ οὐρανοῦ, Latin: De Caelo or De Caelo et Mundo) is Aristotle's chief cosmological treatise: written in 350 BC it contains his astronomical theory and his ideas on the concrete workings of the terrestrial world.
On the Sizes and Distances (of the Sun and Moon) (Περὶ μεγεθῶν καὶ ἀποστημάτων, Peri megethon kai apostematon) is widely accepted as the only extant work written by Aristarchus of Samos, an ancient Greek astronomer who lived circa 310–230 BCE.
The opposition surge (sometimes known as the opposition effect, opposition spike or Seeliger effect) is the brightening of a rough surface, or an object with many particles, when illuminated from directly behind the observer.
In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.
The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in about 27.322 days (a sidereal month) and one revolution relative to the Sun in about 29.530 days (a synodic month).
The orbital period is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars.
The orbital plane of a revolving body is the geometric plane on which its orbit lies.
An order of magnitude is an approximate measure of the number of digits that a number has in the commonly-used base-ten number system.
The origin of the Moon is usually thought to be that a Mars-sized body struck the Earth, making a debris ring that eventually collected into a single natural satellite, the Moon, but there are a number of variations on this giant-impact hypothesis, as well as alternate explanations, and research into how the Moon came to be continues.
The Orion Multi-Purpose Crew Vehicle (Orion MPCV) is an American interplanetary spacecraft intended to carry a crew of four astronauts to destinations at or beyond low Earth orbit (LEO).
The Outer Space Treaty, formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a treaty that forms the basis of international space law.
Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen or absorbed in some material.
The Oxford English Dictionary (OED) is the main historical dictionary of the English language, published by the Oxford University Press.
Oxford University Press (OUP) is the largest university press in the world, and the second oldest after Cambridge University Press.
Oxygen is a chemical element with symbol O and atomic number 8.
Palgrave Macmillan is an international academic and trade publishing company.
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction.
The pascal (symbol: Pa) is the SI derived unit of pressure used to quantify internal pressure, stress, Young's modulus and ultimate tensile strength.
Sir Patrick Alfred Caldwell-Moore (4 March 19239 December 2012) was an English amateur astronomer who attained prominent status in that field as a writer, researcher, radio commentator and television presenter.
A peak of eternal light (PEL) is a hypothetical point on the surface of an astronomical body that is always in sunlight.
Peary is the closest large lunar impact crater to the lunar north pole.
Pergamon Press was an Oxford-based publishing house, founded by Paul Rosbaud and Robert Maxwell, which published scientific and medical books and journals.
In astronomy, perturbation is the complex motion of a massive body subject to forces other than the gravitational attraction of a single other massive body.
Philip Cary Plait (born September 30, 1964), also known as The Bad Astronomer, is an American astronomer, skeptic, writer and popular science blogger.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences is a fortnightly peer-reviewed scientific journal published by the Royal Society.
Photodissociation, photolysis, or photodecomposition is a chemical reaction in which a chemical compound is broken down by photons.
Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group.
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.
Planetary and Space Science, published 15 times per year, is a peer-reviewed scientific journal established in 1959.
The planetary core consists of the innermost layer(s) of a planet; which may be composed of solid and liquid layers.
In planetary science, planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical behaviour, where the body develops into compositionally distinct layers; the denser materials of a planet sink to the center, while less dense materials rise to the surface, generally in a magma ocean.
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites.
Planets in astrology have a meaning different from the modern astronomical understanding of what a planet is.
Planetshine is the dim illumination, by sunlight reflected from a planet, of all or part of the otherwise dark side of any moon orbiting the body.
Pliny the Elder (born Gaius Plinius Secundus, AD 23–79) was a Roman author, naturalist and natural philosopher, a naval and army commander of the early Roman Empire, and friend of emperor Vespasian.
Pluto (minor planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune.
The polar night occurs in the northernmost and southernmost regions of the Earth when the night lasts for more than 24 hours.
Popular Astronomy is an American magazine published by John August Media, LLC and hosted at TechnicaCuriosa.com for amateur astronomers.
Popular Science (also known as PopSci) is an American quarterly magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects.
Potassium is a chemical element with symbol K (from Neo-Latin kalium) and atomic number 19.
Precession is a change in the orientation of the rotational axis of a rotating body.
Precipitation is the creation of a solid from a solution.
A primary (also called a gravitational primary, primary body, or central body) is the main physical body of a gravitationally bound, multi-object system.
Project Horizon was a 1959 study to determine the feasibility of constructing a scientific / military base on the Moon, at a time when the U.S. Department of the Army, Department of the Navy, and Department of the Air Force had total responsibility for U.S. space program plans.
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.
Proto-Germanic (abbreviated PGmc; German: Urgermanisch; also called Common Germanic, German: Gemeingermanisch) is the reconstructed proto-language of the Germanic branch of the Indo-European languages.
Proto-Indo-European (PIE) is the linguistic reconstruction of the hypothetical common ancestor of the Indo-European languages, the most widely spoken language family in the world.
Proto-Indo-European religion is the belief system adhered to by the Proto-Indo-Europeans.
The Psychological Bulletin is a monthly peer-reviewed academic journal that publishes evaluative and integrative research reviews and interpretations of issues in psychology, including both qualitative (narrative) and/or quantitative (meta-analytic) aspects.
Psychological Reports is a bimonthly peer-reviewed academic journal covering research in psychology and psychiatry.
Claudius Ptolemy (Κλαύδιος Πτολεμαῖος, Klaúdios Ptolemaîos; Claudius Ptolemaeus) was a Greco-Roman mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology.
The pyroxenes (commonly abbreviated to Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks.
In traditional Chinese culture, qi or ch'i is believed to be a vital force forming part of any living entity.
The Quadrantids (QUA) are a January meteor shower.
A quake is the result when the surface of a planet, moon or star begins to shake, usually as the consequence of a sudden release of energy transmitted as seismic waves, and potentially with great violence.
A quasi-satellite is an object in a specific type of co-orbital configuration (1:1 orbital resonance) with a planet where the object stays close to that planet over many orbital periods.
A radio telescope is a specialized antenna and radio receiver used to receive radio waves from astronomical radio sources in the sky in radio astronomy.
Radioactive decay (also known as nuclear decay or radioactivity) is the process by which an unstable atomic nucleus loses energy (in terms of mass in its rest frame) by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino in the case of electron capture, gamma ray, or electron in the case of internal conversion.
Radon is a chemical element with symbol Rn and atomic number 86.
The Ranger program was a series of unmanned space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon.
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses) in a late phase of stellar evolution.
Reflectance of the surface of a material is its effectiveness in reflecting radiant energy.
Regolith is a layer of loose, heterogeneous superficial deposits covering solid rock.
A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects light back to its source with a minimum of scattering.
Reviews in Mineralogy and Geochemistry is the official review journal of the Mineralogical Society of America and The Geochemical Society.
RIA Novosti (РИА Новости), sometimes RIA (РИА) for short, was Russia's international news agency until 2013 and continues to be the name of a state-operated domestic Russian-language news agency.
Richard Anthony Proctor (23 March 1837 – 12 September 1888) was an English astronomer.
A rift valley is a linear-shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault.
Routledge is a British multinational publisher.
A rover (or sometimes planetary rover) is a space exploration vehicle designed to move across the surface of a planet or other celestial body.
The Royal Astronomical Society of New Zealand (RASNZ) is the New Zealand national astronomical society.
A sample-return mission is a spacecraft mission with the goal of collecting and returning with tangible samples from an extraterrestrial location to Earth for analysis.
The Saros is a period of approximately 223 synodic months (approximately 6585.3211 days, or 18 years, 11 days, 8 hours), that can be used to predict eclipses of the Sun and Moon.
Science, also widely referred to as Science Magazine, is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals.
The Science Express is a mobile scientific exhibition for children mounted on a train which travels across India.
A seismometer is an instrument that measures motion of the ground, caused by, for example, an earthquake, a volcanic eruption, or the use of explosives.
In Greek mythology, Selene ("Moon") is the goddess of the moon.
SELENE (Selenological and Engineering Explorer), better known in Japan by its nickname, was the second Japanese lunar orbiter spacecraft following the Hiten probe.
Selenium is a chemical element with symbol Se and atomic number 34.
Selenography is the study of the surface and physical features of the Moon.
Seleucus of Seleucia (Σέλευκος Seleukos; born c. 190 BC; fl. c. 150 BC) was a Hellenistic astronomer and philosopher.
Shackleton Energy Company was formed in 2007 in Del Valle, Texas to build equipment and technologies necessary for mining the Moon.
Shen Kuo (1031–1095), courtesy name Cunzhong (存中) and pseudonym Mengqi (now usually given as Mengxi) Weng (夢溪翁),Yao (2003), 544.
Shi Shen (fl. 4th century BC) was a Chinese astronomer and contemporary of Gan De born in the State of Wei, also known as the Shi Shenfu.
A shield volcano is a type of volcano usually composed almost entirely of fluid lava flows.
Sidereus Nuncius (usually Sidereal Messenger, also Starry Messenger or Sidereal Message) is a short astronomical treatise (or pamphlet) published in New Latin by Galileo Galilei on March 13, 1610.
Silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with the chemical formula, most commonly found in nature as quartz and in various living organisms.
Sin (Akkadian: 𒂗𒍪 Su'en, Sîn) or Nanna (Sumerian: 𒀭𒋀𒆠 DŠEŠ.KI, DNANNA) was the god of the moon in the Mesopotamian mythology of Akkad, Assyria and Babylonia.
Skeptical Inquirer is a bimonthly American magazine published by the Committee for Skeptical Inquiry (CSI) with the subtitle: The Magazine for Science and Reason.
SMART-1 was a Swedish-designed European Space Agency satellite that orbited around the Moon.
The Smithsonian Institution, established on August 10, 1846 "for the increase and diffusion of knowledge," is a group of museums and research centers administered by the Government of the United States.
Sodium is a chemical element with symbol Na (from Latin natrium) and atomic number 11.
Sodium oxide is a chemical compound with the formula Na2O.
A soft landing is any type of aircraft, rocket or spacecraft-lander landing that does not result in damage to/the destruction of the vehicle or anything on board.
Software engineering is the application of engineering to the development of software in a systematic method.
A solar calendar is a calendar whose dates indicate the season or almost equivalently the position of the apparent position of the sun in relative to the stars.
A solar eclipse (as seen from the planet Earth) is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and when the Moon fully or partially blocks ("occults") the Sun.
A total solar eclipse occurred on 11 August 1999 with an eclipse magnitude of 1.029.
The Solar SystemCapitalization of the name varies.
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona.
The Song dynasty (960–1279) was an era of Chinese history that began in 960 and continued until 1279.
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface.
The South Pole–Aitken basin is an impact crater on the far side of the Moon.
The Soviet crewed lunar programs were a series of unsuccessful programs pursued by the Soviet Union to land a man on the Moon, in competition with the United States Apollo program to achieve the same goal set publicly by President John F. Kennedy on May 25, 1961.
The Soviet Union, officially the Union of Soviet Socialist Republics (USSR) was a socialist state in Eurasia that existed from 1922 to 1991.
The Space Race refers to the 20th-century competition between two Cold War rivals, the Soviet Union (USSR) and the United States (US), for dominance in spaceflight capability.
Space.com is a space and astronomy news website.
SpaceNews is a print and digital publication that covers business and political news in the space and satellite industry.
Space Exploration Technologies Corp., doing business as SpaceX, is a private American aerospace manufacturer and space transportation services company headquartered in Hawthorne, California.
The splitting of the moon (انشقاق القمر) is a miracle in Muslim tradition attributed to the Islamic prophet Muhammad.
Springer Science+Business Media or Springer, part of Springer Nature since 2015, is a global publishing company that publishes books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing.
Sputtering is a process whereby particles are ejected from a solid target material due to bombardment of the target by energetic particles, particularly gas ions in a laboratory.
The star and crescent is an iconographic symbol used in various historical contexts but most well known today as a symbol of the former Ottoman Empire and, by popular extension, the Islamic world.
STEREO (Solar Terrestrial Relations Observatory) is a solar observation mission.
Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision.
Sterling Publishing Company, Inc. is a publisher of a broad range of subject areas, with multiple imprints and more than 5,000 titles in print.
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification).
Sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.
Sulfur or sulphur is a chemical element with symbol S and atomic number 16.
SumerThe name is from Akkadian Šumeru; Sumerian en-ĝir15, approximately "land of the civilized kings" or "native land".
The Sun is the star at the center of the Solar System.
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light.
A supermoon is a full moon or a new moon that approximately coincides with the closest distance that the Moon reaches to Earth in its elliptic orbit, resulting in a slightly larger-than-usual apparent size of the lunar disk as seen from Earth.
The supernatural (Medieval Latin: supernātūrālis: supra "above" + naturalis "natural", first used: 1520–1530 AD) is that which exists (or is claimed to exist), yet cannot be explained by laws of nature.
Surveyor 1 was the first lunar soft-lander in the unmanned Surveyor program of the National Aeronautics and Space Administration (NASA, United States).
The Surveyor program was a NASA program that, from June 1966 through January 1968, sent seven robotic spacecraft to the surface of the Moon.
In astronomy, a syzygy (from the Ancient Greek σύζυγος suzugos meaning, "yoked together") is a (usually) straight-line configuration of three or more celestial bodies in a gravitational system.
A tally stick (or simply tally) was an ancient memory aid device used to record and document numbers, quantities, or even messages.
The Taurids are an annual meteor shower, associated with the comet Encke.
A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light).
The tesla (symbol T) is a derived unit of magnetic flux density (informally, magnetic field strength) in the International System of Units.
The Astronomical Journal (often abbreviated AJ in scientific papers and references) is a peer-reviewed monthly scientific journal owned by the American Astronomical Society and currently published by IOP Publishing.
The Astrophysical Journal, often abbreviated ApJ (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler.
The New York Times (sometimes abbreviated as The NYT or The Times) is an American newspaper based in New York City with worldwide influence and readership.
The Planetary Society is an American internationally active, non-governmental, nonprofit foundation.
The Press-Enterprise is a paid daily newspaper published by Digital First Media that serves the Inland Empire in Southern California.
The Space Review is a free online publication, published weekly with in-depth articles, essays, commentary and reviews on space exploration and development.
Theia is a hypothesized ancient planetary-mass object in the early Solar System that, according to the giant impact hypothesis, collided with another planetary-mass object, Gaia (the early Earth) around 4.5 billion years ago.
Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon), and the primary planet that it orbits (e.g. Earth).
The tidal force is an apparent force that stretches a body 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 the diverse phenomena, including tides, tidal locking, breaking apart of celestial bodies and formation of ring systems within Roche limit, and in extreme cases, spaghettification of objects.
Tidal locking (also called gravitational locking or captured rotation) occurs when the long-term interaction between a pair of co-orbiting astronomical bodies drives the rotation rate of at least one of them into the state where there is no more net transfer of angular momentum between this body (e.g. a planet) and its orbit around the second body (e.g. a star); this condition of "no net transfer" must be satisfied over the course of one orbit around the second body.
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of Earth.
While predictions of the future can never be absolutely certain, present understanding in various scientific fields allows for the prediction of far-future events, if only in the broadest outline.
Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula.
The topography of the Moon has been measured by the methods of laser altimetry and stereo image analysis, most recently from data obtained during the Clementine mission.
Torque, moment, or moment of force is rotational force.
Lunar tourism may be possible in the future if trips to the Moon are made available to a private audience.
A transient lunar phenomenon (TLP) or lunar transient phenomenon (LTP) is a short-lived light, color, or change in appearance on the surface of the Moon.
Trigonometry (from Greek trigōnon, "triangle" and metron, "measure") is a branch of mathematics that studies relationships involving lengths and angles of triangles.
The tropics are a region of the Earth surrounding the Equator.
The United Nations Office for Outer Space Affairs (UNOOSA) is a part of the United Nations Secretariat, located at the United Nations Office in Vienna.
The United States of America (USA), commonly known as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major self-governing territories, and various possessions.
The United States Geological Survey (USGS, formerly simply Geological Survey) is a scientific agency of the United States government.
The United States Navy (USN) is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States.
Universe Today (UT) is a popular North American-based non-commercial space and astronomy news website.
The University of Arizona Press, a publishing house founded in 1959 as a department of the University of Arizona, is a nonprofit publisher of scholarly and regional books.
The University of California, Los Angeles (UCLA) is a public research university in the Westwood district of Los Angeles, United States.
The University of Illinois Urbana–Champaign (also known as U of I, Illinois, or colloquially as the University of Illinois or UIUC) is a public research university in the U.S. state of Illinois and the flagship institution of the University of Illinois System.
The University of St Andrews (informally known as St Andrews University or simply St Andrews; abbreviated as St And, from the Latin Sancti Andreae, in post-nominals) is a British public research university in St Andrews, Fife, Scotland.
Unmanned spacecraft are spacecraft without people ("man") on board, used for unmanned spaceflight.
Utrecht University (UU; Universiteit Utrecht, formerly Rijksuniversiteit Utrecht) is a university in Utrecht, the Netherlands.
Utu later worshipped by East Semitic peoples as Shamash, was the ancient Mesopotamian god of the sun, justice, morality, and truth, and the twin brother of the goddess Inanna, the Queen of Heaven.
Vacuum is space devoid of matter.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.
The Vision for Space Exploration (VSE) was a plan for space exploration announced on January 14, 2004 by President George W. Bush.
The visual system is the part of the central nervous system which gives organisms the ability to process visual detail, as well as enabling the formation of several non-image photo response functions.
Vodafone Group plc is a British multinational telecommunications conglomerate, with headquarters in London.
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
A weapon of mass destruction (WMD) is a nuclear, radiological, chemical, biological or other weapon that can kill and bring significant harm to a large number of humans or cause great damage to human-made structures (e.g., buildings), natural structures (e.g., mountains), or the biosphere.
A wet moon (also called a Cheshire moon) is the visual phenomenon when the "horns" of the crescent Moon point up at an angle, away from the horizon, so that the crescent takes on the appearance of a bowl or smile.
Wilhelm Wolff Beer (4 January 1797 – 27 March 1850) was a banker and astronomer from Berlin, Prussia, and the brother of Giacomo Meyerbeer.
XPRIZE is a nonprofit organization that designs and manages public competitions intended to encourage technological development that could benefit humanity.
Xinhua News Agency (English pronunciation: J. C. Wells: Longman Pronunciation Dictionary, 3rd ed., for both British and American English) or New China News Agency is the official state-run press agency of the People's Republic of China.
YouTube is an American video-sharing website headquartered in San Bruno, California.
Yutu is an unmanned lunar rover that formed part of the Chinese Chang'e 3 mission to the Moon.
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere.
A zenith telescope is a type of telescope that is designed to point straight up at or near the zenith.
Zooplankton are heterotrophic (sometimes detritivorous) plankton.
3753 Cruithne (For instance, on the British television show Q.I. (Season 1; aired 11 Sept 2003).) is a Q-type, Aten asteroid in orbit around the Sun in 1:1 orbital resonance with Earth, making it a co-orbital object.
Vesta, minor-planet designation 4 Vesta, is one of the largest objects in the asteroid belt, with a mean diameter of.
4179 Toutatis, provisional designation, is an elongated, stony asteroid and slow rotator, classified as near-Earth object and potentially hazardous asteroid of the Apollo and Alinda group, approximately 2.5 kilometers in diameter.
4G is the fourth generation of broadband cellular network technology, succeeding 3G.
The 7th century BC began the first day of 700 BC and ended the last day of 601 BC.
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