582 relations: Abiogenesis, Abyssal plain, Acceleration, Accretion (astrophysics), Acid rain, Aerobic organism, African Plate, Age of the Earth, Alert, Nunavut, Allotropes of oxygen, Alpine tundra, Aluminium, Aluminium oxide, Amphibole, Amundsen–Scott South Pole Station, Anaerobic organism, Ancient Greek, Andesite, Angles, Anglo-Saxon paganism, Angular diameter, Angular velocity, Antarctic Circle, Antarctic ice sheet, Antarctic Plate, Antarctica, Anthropomorphism, Apollo 13, Apollo 17, Apollo program, Arabian Plate, Arctic Circle, Argon, Arid, Arizona State University, Article (grammar), Associated Press, Asthenosphere, Astrobiology (journal), Astronomical object, Atmosphere of Earth, Atmospheric circulation, Atmospheric escape, Atmospheric pressure, Aurora, Australia, Axial tilt, Ælfric of Eynsham, Barycenter, Basalt, ..., Beowulf, Bible, Billiard ball, Biodiversity, Biogenic substance, Biome, Biosphere, Biotic material, Bir Tawil, Bird, Blizzard, Bond albedo, Book of Genesis, Boydell & Brewer, Building material, Bya, C4 carbon fixation, Calcite, Calcium, Calcium oxide, Cambrian explosion, Carbon cycle, Carbon dioxide, Carbonate minerals, Caribbean Plate, Cartography, Celestial equator, Celestial pole, Celestial sphere, Cengage, Center of mass, Challenger Deep, Chandler wobble, Charged particle, Charon (moon), Chemical element, Chemical reaction, Chemical substance, Chicxulub impactor, Chimborazo, Circumference, Circumscribed circle, Circumstellar disc, Civilization, Climate, Clockwise, Coal, Cocos Plate, Colony (biology), Comet, Continent, Continental climate, Continental crust, Continental shelf, Convergent boundary, Coral reef, Cosmas Indicopleustes, Cosmic dust, Creation myth, Cretaceous–Paleogene extinction event, Croatia–Serbia border dispute, Culture, Cyclone, Dead Sea, Death Valley National Park, Definiteness, Deforestation, Deity, Dependent territory, Desert, Desertification, Developing country, Devonian, Diagenesis, Dinosaur, Dipole, Divergent boundary, Dolomite, Dwarf planet, Dynamo theory, Earliest known life forms, Early Modern English, Earth and Planetary Science Letters, Earth goddess, Earth mass, Earth physical characteristics tables, Earth science, Earth System Research Laboratory, Earth system science, Earth trojan, Earth's magnetic field, Earth's orbit, Earth's rotation, Earthquake, East Antarctica, Ecliptic, Ecosystem, Ecuador, El Niño–Southern Oscillation, Elevation, Ellesmere Island, Epoch (astronomy), Equator, Equatorial bulge, Equinox, Erosion, Erosion and tectonics, Escape velocity, Eukaryote, Eurasian Plate, European Terrestrial Reference System 1989, Evolution, Excite, Exosphere, Extinction, Extinction event, Faint young Sun paradox, Feldspar, Figure of the Earth, Fixed stars, Flat Earth, Flood, Flood basalt, Flower, Formation and evolution of the Solar System, Fossil, Fossil fuel, Four corners of the world, Frequency, Fresh water, Furnace Creek, California, Gaia, Gaia hypothesis, Galactic plane, Gene, Genesis A, Geocentric model, Geodesy, Geodetic datum, Geographical pole, Geography, Geoid, Geologic time scale, Geological history of Earth, Geology, Geomagnetic reversal, Geomagnetic secular variation, Geomagnetic storm, Geometric albedo, Geophysical Research Letters, Germania (book), Germanic languages, Germanic paganism, Giant-impact hypothesis, Glacial period, Glacier, Global warming, Gould Belt, Granite, Graphite, Gravitational acceleration, Gravity, Gravity anomaly, Gravity of Earth, Great Oxygenation Event, Great Plains, Greenhouse effect, Greenhouse gas, Greenland, Heliocentrism, Heptateuch, Hill sphere, History of agriculture, History of Earth, Hotspot (geology), Human, Human evolution, Human impact on the environment, Humid subtropical climate, Humidity, Hurricane Felix, Hydrogen, Hydrosphere, Hyperpower, Ice age, Ice cap, Ice crystals, Ice shelf, Impact event, Indo-Australian Plate, Inner core, Inorganic compound, Internal heating, International Earth Rotation and Reference Systems Service, International law, International organization, International Space Station, International System of Units, Invariable plane, Iron, Iron(II) oxide, Iron(III) oxide, Irrigation, Island, Isotope, Isotopes of thorium, James Ussher, Jörð, Journal of African Earth Sciences, Junius manuscript, Kaikō ROV, Kármán line, Köppen climate classification, Kelvin, King James Version, Kitaa, Komatiite, Lagrangian point, Landform, Landslide, Laniakea Supercluster, Lapse rate, Last universal common ancestor, Late Heavy Bombardment, Latin, Latitude, Latitudinal gradients in species diversity, Lenticular cloud, Life, Light-year, Limestone, Lindisfarne Gospels, List of fertility deities, List of gravitationally rounded objects of the Solar System, List of International Space Station expeditions, List of sovereign states, List of states with limited recognition, List of tectonic plates, Local Group, Luke 13, Lunar eclipse, Lunar month, Lunar phase, Magmatism, Magnesium, Magnesium oxide, Magnetic moment, Magnetosphere, Mammal, Mantle (geology), Mantle convection, Mantle plume, March equinox, Mariana Trench, Mars, Mass segregation (astronomy), Matthew 28, Medication, Member states of the United Nations, Meridian (astronomy), Mesosphere, Metabolism, Metamorphic rock, Metasedimentary rock, Meteoroid, Methane, Mica, Microbial mat, Microorganism, Microsecond, Mid-ocean ridge, Middle English, Midnight sun, Milankovitch cycles, Milky Way, Millisecond, Mindspark Interactive Network, Modern English, Mohorovičić discontinuity, Mojave Desert, Molecular cloud, Molecular mass, Monthly Notices of the Royal Astronomical Society, Moon, Mother goddess, Mount Discovery, Mount Everest, NASA, National Geospatial-Intelligence Agency, National Institute of Standards and Technology, National Oceanic and Atmospheric Administration, National Science Foundation, Natural gas, Natural resource, Natural satellite, Nature (journal), Nature Geoscience, Nature Publishing Group, Navigation, Nazca Plate, Near-Earth object, Nebular hypothesis, Neoproterozoic, Nerthus, Nickel, Nitrogen, Nitrous oxide, Non-renewable resource, Norse mythology, North American Plate, Northern Canada, Northern Hemisphere, Nunavut, Nutation, Observable universe, Ocean, Ocean current, Oceanic crust, Oceanic plateau, Oceanic trench, Old English, Olivine, Orders of magnitude (mass), Ore, Ore genesis, Organic compound, Organism, Origin of water on Earth, Orion Arm, Orogeny, Orrorin, Outer core, Outer space, Outgassing, Outline of Earth, Overgrazing, Oxford spelling, Oxygen, Ozone, Ozone layer, Ozone–oxygen cycle, Pacific Plate, Paleontology, Pangaea, Pannotia, Pedogenesis, Pedosphere, Perihelion and aphelion, Petroleum, Phase transition, Phosphorus pentoxide, Photosynthesis, Planet, Planet Nine, Planetary habitability, Planetesimal, Plate tectonics, Pleistocene, PLOS Biology, Pluto, Polar climate, Polar motion, Polar night, Polar regions of Earth, Pollution, Potassium oxide, Potassium-40, Precession, Pressure ridge (ice), Primordial nuclide, Proceedings of the National Academy of Sciences of the United States of America, Properties of water, Proto-Germanic language, Protoplanet, Pyroxene, Pythagoras, Quartz, Quasi-satellite, Quasiperiodic motion, Radioactive decay, Radiometric dating, Red giant, Redox, Reflection (physics), Rheology, Rodinia, Rotation, Rudolf Simek, Saline water, Salinity, Sandstone, Satellite, Scale height, Scandinavian Peninsula, Scientific consensus, Scotia Plate, Sea level, Sea level rise, Season, Secular variation, Sedimentary rock, Semi-major and semi-minor axes, Shrew, Sidereal time, Sidereal year, Silicate minerals, Silicon, Silicon dioxide, Sinkhole, Snowball Earth, Society, Sodium oxide, Soil, Soil fertility, Soil retrogression and degradation, Solar eclipse, Solar irradiance, Solar luminosity, Solar System, Solar time, Solar wind, Solid angle, Solstice, Somali Plate, South American Plate, South Pole, Southern Hemisphere, Sovereignty, Space debris, Space.com, Species, Spherical Earth, Spheroid, Stellar evolution, Stratosphere, Style guide, Subduction, Submarine canyon, Substorm, Subtropics, Sulfur, Summer, Summer solstice, Sun, Supercontinent, Surveying, Symbiogenesis, Tacitus, Temperate climate, Terminator (solar), Terra, Terra (mythology), Terra nullius, Terrain, Terrestrial planet, Tesla (unit), The Alcalde, The Blue Marble, The New York Times, The Rise and Fall of the Great Powers, Theia (planet), Thermal energy, Thermal reservoir, Thermodynamics, Thermohaline circulation, Thermosphere, Thor, Tidal acceleration, Tidal locking, Tide, Timeline of natural history, Timeline of the far future, Titanium dioxide, Tonne, Topography, Topsoil, Tornado, Torque, Trade winds, Transform fault, Transition zone (Earth), Tropic of Cancer, Tropic of Capricorn, Tropical climate, Tropical cyclone, Tropical rainforest, Tropical year, Tropics, Troposphere, Tsunami, Tundra, Types of volcanic eruptions, Typhoon, Ultraviolet, Union of Concerned Scientists, United Nations, United Nations General Assembly observers, United States Department of Commerce, United States Geological Survey, Universe, University of Wisconsin–Madison, Uranium-238, Van Allen radiation belt, Vanguard 1, Vector Map, Virgo Supercluster, Viscosity, Volcanism, Volcano, Vostok Station, Water, Water cycle, Water distribution on Earth, Water vapor, Weathering, Wessex Gospels, Westerlies, Western Australia, Wildfire, William Thomson, 1st Baron Kelvin, Wind, Winter, Winter solstice, Wood, World Geodetic System, World Meteorological Organization, World population, Yale University Press, Year, Yuri Gagarin, Zonal and meridional, 3753 Cruithne. Expand index (532 more) »
Abiogenesis, or informally the origin of life,Compare: Also occasionally called biopoiesis.
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and.
In physics, acceleration is the rate of change of velocity of an object with respect to time.
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, in an accretion disk.
Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH).
An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.
The African Plate is a major tectonic plate straddling the equator as well as the prime meridian.
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.
Alert, in the Qikiqtaaluk Region, Nunavut, Canada, is the northernmost permanently inhabited place in the world, ("Twice a year, the military resupply Alert, the world's northernmost settlement.") at latitude 82°30'05" north, from the North Pole.
There are several known allotropes of oxygen.
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high altitude.
Aluminium or aluminum is a chemical element with symbol Al and atomic number 13.
Aluminium oxide (British English) or aluminum oxide (American English) is a chemical compound of aluminium and oxygen with the chemical formula 23.
Amphibole is an important group of generally dark-colored, inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures.
The Amundsen–Scott South Pole Station is a United States scientific research station at the South Pole, the southernmost place on the Earth.
An anaerobic organism or anaerobe is any organism that does not require oxygen for growth.
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.
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture.
The Angles (Angli) were one of the main Germanic peoples who settled in Great Britain in the post-Roman period.
Anglo-Saxon paganism, sometimes termed Anglo-Saxon heathenism, Anglo-Saxon pre-Christian religion, or Anglo-Saxon traditional religion, refers to the religious beliefs and practices followed by the Anglo-Saxons between the 5th and 8th centuries AD, during the initial period of Early Medieval England.
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, the angular velocity of a particle is the rate at which it rotates around a chosen center point: that is, the time rate of change of its angular displacement relative to the origin.
The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of the Earth.
The Antarctic ice sheet is one of the two polar ice caps of the Earth.
The Antarctic Plate is a tectonic plate containing the continent of Antarctica and extending outward under the surrounding oceans.
Antarctica is Earth's southernmost continent.
Anthropomorphism is the attribution of human traits, emotions, or intentions to non-human entities.
Apollo 13 was the seventh manned mission in the Apollo space program and the third intended to land on the Moon.
Apollo 17 was the final mission of NASA's Apollo 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.
The Arabian Plate is a tectonic plate in the northern and eastern hemispheres.
The Arctic Circle is the most northerly of the five major circles of latitude as shown on maps of Earth.
Argon is a chemical element with symbol Ar and atomic number 18.
A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of plant and animal life.
Arizona State University (commonly referred to as ASU or Arizona State) is a public metropolitan research university on five campuses across the Phoenix metropolitan area, and four regional learning centers throughout Arizona.
An article (with the linguistic glossing abbreviation) is a word that is used with a noun (as a standalone word or a prefix or suffix) to specify grammatical definiteness of the noun, and in some languages extending to volume or numerical scope.
The Associated Press (AP) is a U.S.-based not-for-profit news agency headquartered in New York City.
The asthenosphere (from Greek ἀσθενής asthenḗs 'weak' + "sphere") is the highly viscous, mechanically weak and ductilely deforming region of the upper mantle of the Earth.
Astrobiology is a peer-reviewed scientific journal covering research on the origin, evolution, distribution and future of life across the universe.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
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 circulation is the large-scale movement of air, and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth.
Atmospheric escape is the loss of planetary atmospheric gases to outer space.
Atmospheric pressure, sometimes also called barometric pressure, is the pressure within the atmosphere of Earth (or that of another planet).
An aurora (plural: auroras or aurorae), sometimes referred to as polar lights, northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in the Earth's sky, predominantly seen in the high-latitude regions (around the Arctic and Antarctic).
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands.
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.
Ælfric of Eynsham (Ælfrīc; Alfricus, Elphricus) was an English abbot, as well as a consummate, prolific writer in Old English of hagiography, homilies, biblical commentaries, and other genres.
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.
Beowulf is an Old English epic story consisting of 3,182 alliterative lines.
The Bible (from Koine Greek τὰ βιβλία, tà biblía, "the books") is a collection of sacred texts or scriptures that Jews and Christians consider to be a product of divine inspiration and a record of the relationship between God and humans.
A billiard ball is a small, hard ball used in cue sports, such as carom billiards, pool, and snooker.
Biodiversity, a portmanteau of biological (life) and diversity, generally refers to the variety and variability of life on Earth.
A biogenic substance is a substance produced by life processes.
A biome is a community of plants and animals that have common characteristics for the environment they exist in.
The biosphere (from Greek βίος bíos "life" and σφαῖρα sphaira "sphere") also known as the ecosphere (from Greek οἶκος oîkos "environment" and σφαῖρα), is the worldwide sum of all ecosystems.
Biotic material or biological derived material is any material that originates from living organisms.
Bir Tawil or Bi'r Tawīl (or بئر طويل, meaning "tall water well") is a area along the border between Egypt and Sudan, which is uninhabited and claimed by neither country.
Birds, also known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.
A blizzard is a severe snowstorm characterized by strong sustained winds of at least and lasting for a prolonged period of time—typically three hours or more.
The Bond albedo, named after the American astronomer George Phillips Bond (1825–1865), who originally proposed it, is the fraction of power in the total electromagnetic radiation incident on an astronomical body that is scattered back out into space.
The Book of Genesis (from the Latin Vulgate, in turn borrowed or transliterated from Greek "", meaning "Origin"; בְּרֵאשִׁית, "Bərēšīṯ", "In beginning") is the first book of the Hebrew Bible (the Tanakh) and the Old Testament.
Boydell & Brewer is an academic press based in Woodbridge, Suffolk, England that specializes in publishing historical and critical works.
Building material is any material which is used for construction purposes.
bya or b.y.a. is an abbreviation for "billion years ago".
C4 carbon fixation or the Hatch-Slack pathway is a photosynthetic process in some plants.
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3).
Calcium is a chemical element with symbol Ca and atomic number 20.
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound.
The Cambrian explosion or Cambrian radiation was an event approximately in the Cambrian period when most major animal phyla appeared in the fossil record.
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.
Carbon dioxide (chemical formula) is a colorless gas with a density about 60% higher than that of dry air.
Carbonate minerals are those minerals containing the carbonate ion, CO32−.
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America.
Cartography (from Greek χάρτης chartēs, "papyrus, sheet of paper, map"; and γράφειν graphein, "write") is the study and practice of making maps.
The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.
The north and south celestial poles are the two imaginary points in the sky where the Earth's axis of rotation, indefinitely extended, intersects the celestial sphere.
In astronomy and navigation, the celestial sphere is an abstract sphere with an arbitrarily large radius concentric to Earth.
Cengage is an educational content, technology, and services company for the higher education, K-12, professional, and library markets worldwide.
In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero, or the point where if a force is applied it moves in the direction of the force without rotating.
The Challenger Deep is the deepest known point in the Earth's seabed hydrosphere, with a depth of by direct measurement from submersibles, and slightly more by sonar bathymetry.
The Chandler wobble or variation of latitude is a small deviation in the Earth's axis of rotation relative to the solid earth, which was discovered by American astronomer Seth Carlo Chandler in 1891.
In physics, a charged particle is a particle with an electric charge.
Charon, also known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto.
A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z).
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.
A chemical substance, also known as a pure substance, is a form of matter that consists of molecules of the same composition and structure.
The Chicxulub impactor, also known as the K/Pg impactor and (more speculatively) as the Chicxulub asteroid, was an asteroid in diameter which struck the Earth at the end of the Cretaceous, approximately 66 million years ago, creating the Chicxulub crater.
Chimborazo is a currently inactive stratovolcano in the Cordillera Occidental range of the Andes.
In geometry, the circumference (from Latin circumferentia, meaning "carrying around") of a circle is the (linear) distance around it.
In geometry, the circumscribed circle or circumcircle of a polygon is a circle which passes through all the vertices of the polygon.
A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a star.
A civilization or civilisation (see English spelling differences) is any complex society characterized by urban development, social stratification imposed by a cultural elite, symbolic systems of communication (for example, writing systems), and a perceived separation from and domination over the natural environment.
Climate is the statistics of weather over long periods of time.
Two-dimensional rotation can occur in two possible directions.
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams.
The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it.
In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another.
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.
A continent is one of several very large landmasses of the world.
Continental climates are defined in the Köppen climate classification as having the coldest month with the temperature never rising above 0.0° C (32°F) all month long.
Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the continents and the areas of shallow seabed close to their shores, known as continental shelves.
The continental shelf is an underwater landmass which extends from a continent, resulting in an area of relatively shallow water known as a shelf sea.
In plate tectonics, a convergent boundary, also known as a destructive plate boundary, is a region of active deformation where two or more tectonic plates or fragments of the lithosphere are near the end of their life cycle.
Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals.
Cosmas Indicopleustes (Greek Κοσμᾶς Ἰνδικοπλεύστης, literally "Cosmas who sailed to India"; also known as Cosmas the Monk) was a Greek merchant and later hermit from Alexandria of Egypt.
Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, as well as all over planet Earth.
A creation myth (or cosmogonic myth) is a symbolic narrative of how the world began and how people first came to inhabit it.
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction, was a sudden mass extinction of some three-quarters of the plant and animal species on Earth, approximately 66 million years ago.
The Croatia–Serbia border dispute refers to differing views held by Croatia and Serbia regarding their border in the area of the Danube River.
Culture is the social behavior and norms found in human societies.
In meteorology, a cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure.
The Dead Sea (יָם הַמֶּלַח lit. Sea of Salt; البحر الميت The first article al- is unnecessary and usually not used.) is a salt lake bordered by Jordan to the east and Israel and Palestine to the west.
Death Valley National Park is an American national park that straddles the California—Nevada border, east of the Sierra Nevada.
In linguistics, definiteness is a semantic feature of noun phrases (NPs), distinguishing between referents/entities that are identifiable in a given context (definite noun phrases) and entities which are not (indefinite noun phrases).
Deforestation, clearance, or clearing is the removal of a forest or stand of trees where the land is thereafter converted to a non-forest use.
A deity is a supernatural being considered divine or sacred.
A dependent territory, dependent area or dependency is a territory that does not possess full political independence or sovereignty as a sovereign state yet remains politically outside the controlling state's integral area.
A desert is a barren area of landscape where little precipitation occurs and consequently living conditions are hostile for plant and animal life.
Desertification is a type of land degradation in which a relatively dry area of land becomes increasingly arid, typically losing its bodies of water as well as vegetation and wildlife.
A developing country (or a low and middle income country (LMIC), less developed country, less economically developed country (LEDC), underdeveloped country) is a country with a less developed industrial base and a low Human Development Index (HDI) relative to other countries.
The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya.
Diagenesis is the change of sediments or existing sedimentary rocks into a different sedimentary rock during and after rock formation (lithification), at temperatures and pressures less than that required for the formation of metamorphic rocks.
Dinosaurs are a diverse group of reptiles of the clade Dinosauria.
In electromagnetism, there are two kinds of dipoles.
In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.
Dolomite is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite.
A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite.
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field.
The earliest known life forms on Earth are putative fossilized microorganisms found in hydrothermal vent precipitates.
Early Modern English, Early New English (sometimes abbreviated to EModE, EMnE or EME) is the stage of the English language from the beginning of the Tudor period to the English Interregnum and Restoration, or from the transition from Middle English, in the late 15th century, to the transition to Modern English, in the mid-to-late 17th century.
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.
An Earth goddess is a deification of the Earth.
Earth mass (where ⊕ is the standard astronomical symbol for planet Earth) is the unit of mass equal to that of Earth.
These are tables showing the physical characteristics of Earth.
Earth science or geoscience is a widely embraced term for the fields of natural science related to the planet Earth.
The Earth System Research Laboratory (ESRL) is a laboratory in National Oceanic and Atmospheric Administration's (NOAA) Office of Oceanic and Atmospheric Research (OAR).
Earth system science (ESS) is the application of systems science to the Earth sciences.
An Earth trojan is an asteroid that orbits the Sun in the vicinity of the Earth–Sun Lagrangian points (leading 60°) or (trailing 60°), thus having an orbit similar to Earth's.
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's orbit is the trajectory along which Earth travels around the Sun.
Earth's rotation is the rotation of Planet Earth around its own axis.
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves.
East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains.
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 ecosystem is a community made up of living organisms and nonliving components such as air, water, and mineral soil.
Ecuador (Ikwadur), officially the Republic of Ecuador (República del Ecuador, which literally translates as "Republic of the Equator"; Ikwadur Ripuwlika), is a representative democratic republic in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean to the west.
El Niño–Southern Oscillation (ENSO) is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting climate of much of the tropics and subtropics.
The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vertical datum).
Ellesmere Island (Inuit: Umingmak Nuna, meaning "land of muskoxen"; Île d'Ellesmere) is part of the Qikiqtaaluk Region in the Canadian territory of Nunavut.
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.
An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).
An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the force exerted by its rotation.
An equinox is commonly regarded as the moment the plane (extended indefinitely in all directions) of Earth's equator passes through the center of the Sun, which occurs twice each year, around 20 March and 22-23 September.
In earth science, erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth's crust, and then transport it to another location (not to be confused with weathering which involves no movement).
The interaction between erosion and tectonics has been a topic of debate since the early 1990s.
In physics, escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a massive body.
Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, unlike Prokaryotes (Bacteria and other Archaea).
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia.
The European Terrestrial Reference System 1989 (ETRS89) is an ECEF (Earth-Centered, Earth-Fixed) geodetic Cartesian reference frame, in which the Eurasian Plate as a whole is static.
Evolution is change in the heritable characteristics of biological populations over successive generations.
Excite (stylized as excite) is an internet portal launched in December 1995 that provides a variety of content including news and weather, a metasearch engine, a web-based email, instant messaging, stock quotes, and a customizable user homepage.
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.
In biology, extinction is the termination of an organism or of a group of organisms (taxon), normally a species.
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth.
The faint young Sun paradox or faint young Sun problem describes the apparent contradiction between observations of liquid water early in Earth's history and the astrophysical expectation that the Sun's output would be only 70 percent as intense during that epoch as it is during the modern epoch.
Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight.
The figure of the Earth is the size and shape of the Earth in geodesy.
The fixed stars (stellae fixae) comprise the background of astronomical objects that appear to not move relative to each other in the night sky compared to the foreground of Solar System objects that do.
The flat Earth model is an archaic conception of Earth's shape as a plane or disk.
A flood is an overflow of water that submerges land that is usually dry.
A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava.
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms).
The formation and evolution of the Solar System began 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud.
A fossil (from Classical Latin fossilis; literally, "obtained by digging") is any preserved remains, impression, or trace of any once-living thing from a past geological age.
A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.
Several cosmological and mythological systems portray four corners of the world or four quarters of the world corresponding approximately to the four points of the compass (or the two solstices and two equinoxes).
Frequency is the number of occurrences of a repeating event per unit of time.
Fresh water (or freshwater) is any naturally occurring water except seawater and brackish water.
Furnace Creek is a census-designated place (CDP) in Inyo County, California.
In Greek mythology, Gaia (or; from Ancient Greek Γαῖα, a poetical form of Γῆ Gē, "land" or "earth"), also spelled Gaea, is the personification of the Earth and one of the Greek primordial deities.
The Gaia hypothesis, also known as the Gaia theory or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet.
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies.
In biology, a gene is a sequence of DNA or RNA that codes for a molecule that has a function.
Genesis A (or Elder Genesis) is the earlier half of an Old English poetic adaptation of the Biblical book of Genesis.
In astronomy, the geocentric model (also known as geocentrism, or the Ptolemaic system) is a superseded description of the universe with Earth at the center.
Geodesy, also known as geodetics, is the earth science of accurately measuring and understanding three of Earth's fundamental properties: its geometric shape, orientation in space, and gravitational field.
A geodetic datum or geodetic system is a coordinate system, and a set of reference points, used to locate places on the Earth (or similar objects).
A geographical pole is either of the two points on a rotating body (planet, dwarf planet, natural satellite, sphere...etc) where its axis of rotation intersects its surface.
Geography (from Greek γεωγραφία, geographia, literally "earth description") is a field of science devoted to the study of the lands, the features, the inhabitants, and the phenomena of Earth.
The geoid is the shape that the surface of the oceans would take under the influence of Earth's gravity and rotation alone, in the absence of other influences such as winds and tides.
The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to time.
The geological history of Earth follows the major events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy).
Geology (from the Ancient Greek γῆ, gē, i.e. "earth" and -λoγία, -logia, i.e. "study of, discourse") is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time.
A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged, while geographic north and geographic south remain the same.
Geomagnetic secular variation refers to changes in the Earth's magnetic field on time scales of about a year or more.
A geomagnetic storm (commonly referred to as a solar storm) is a temporary disturbance of the Earth's magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earth's magnetic field.
In astronomy, the geometric albedo of a celestial body is the ratio of its actual brightness as seen from the light source (i.e. at zero phase angle) to that of an idealized flat, fully reflecting, diffusively scattering (Lambertian) disk with the same cross-section.
Geophysical Research Letters is a biweekly peer-reviewed scientific journal of geoscience published by the American Geophysical Union that was established in 1974.
The Germania, written by the Roman historian Publius Cornelius Tacitus around 98 and originally entitled On the Origin and Situation of the Germans (De Origine et situ Germanorum), was a historical and ethnographic work on the Germanic tribes outside the Roman Empire.
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.
Germanic religion refers to the indigenous religion of the Germanic peoples from the Iron Age until Christianisation during the Middle Ages.
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.
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances.
A glacier is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years, often centuries.
Global warming, also referred to as climate change, is the observed century-scale rise in the average temperature of the Earth's climate system and its related effects.
The Gould Belt is a partial ring of stars in the Milky Way, about 3000 light years across, tilted toward the galactic plane by about 16 to 20 degrees.
Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture.
Graphite, archaically referred to as plumbago, is a crystalline allotrope of carbon, a semimetal, a native element mineral, and a form of coal.
In physics, gravitational acceleration is the acceleration on an object caused by the force of gravitation.
Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another.
A gravity anomaly is the difference between the observed acceleration of free fall, or gravity, on a planet's surface, and the corresponding value predicted from a model of the planet's gravity field.
The gravity of Earth, which is denoted by, refers to the acceleration that is imparted to objects due to the distribution of mass within Earth.
The Great Oxygenation Event, the beginning of which is commonly known in scientific media as the Great Oxidation Event (GOE, also called the Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, Oxygen Revolution, or Great Oxidation) was the biologically induced appearance of dioxygen (O2) in Earth's atmosphere.
The Great Plains (sometimes simply "the Plains") is the broad expanse of flat land (a plain), much of it covered in prairie, steppe, and grassland, that lies west of the Mississippi River tallgrass prairie in the United States and east of the Rocky Mountains in the U.S. and Canada.
The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphere.
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range.
Greenland (Kalaallit Nunaat,; Grønland) is an autonomous constituent country within the Kingdom of Denmark between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago.
Heliocentrism is the astronomical model in which the Earth and planets revolve around the Sun at the center of the Solar System.
The Heptateuch (seven containers) is a name sometimes given to the first seven books of the Hebrew Bible.
An astronomical body's Hill sphere is the region in which it dominates the attraction of satellites.
The history of agriculture records the domestication of plants and animals and the development and dissemination of techniques for raising them productively.
The history of Earth concerns the development of planet Earth from its formation to the present day.
In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle.
Humans (taxonomically Homo sapiens) are the only extant members of the subtribe Hominina.
Human evolution is the evolutionary process that led to the emergence of anatomically modern humans, beginning with the evolutionary history of primates – in particular genus Homo – and leading to the emergence of Homo sapiens as a distinct species of the hominid family, the great apes.
Human impact on the environment or anthropogenic impact on the environment includes changes to biophysical environments and ecosystems, biodiversity, and natural resources caused directly or indirectly by humans, including global warming, environmental degradation (such as ocean acidification), mass extinction and biodiversity loss, ecological crises, and ecological collapse.
A humid subtropical climate is a zone of climate characterized by hot and humid summers, and mild to cool winters.
Humidity is the amount of water vapor present in the air.
Hurricane Felix was the southernmost landfalling Category 5 hurricane in the Atlantic; surpassing Hurricane Edith of 1971.
Hydrogen is a chemical element with symbol H and atomic number 1.
The hydrosphere (from Greek ὕδωρ hydōr, "water" and σφαῖρα sphaira, "sphere") is the combined mass of water found on, under, and above the surface of a planet, minor planet or natural satellite.
A hyperpower is a state that dominates all other states in every domain (i.e. military, culture, economy) and is considered to be a step higher than a superpower.
An ice age is a period of long-term reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers.
An ice cap is a mass of ice that covers less than 50,000 km2 of land area (usually covering a highland area).
Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust.
An ice shelf is a thick floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface.
An impact event is a collision between astronomical objects causing measurable effects.
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters.
The Earth's inner core is the Earth's innermost part.
An inorganic compound is typically a chemical compound that lacks C-H bonds, that is, a compound that is not an organic compound, but the distinction is not defined or even of particular interest.
Internal heat is the heat source from the interior of celestial objects, such as stars, brown dwarfs, planets, moons, dwarf planets, and (in the early history of the Solar System) even asteroids such as Vesta, resulting from contraction caused by gravity (the Kelvin–Helmholtz mechanism), nuclear fusion, tidal heating, core solidification (heat of fusion released as molten core material solidifies), and radioactive decay.
The International Earth Rotation and Reference Systems Service (IERS), formerly the International Earth Rotation Service, is the body responsible for maintaining global time and reference frame standards, notably through its Earth Orientation Parameter (EOP) and International Celestial Reference System (ICRS) groups.
International law is the set of rules generally regarded and accepted as binding in relations between states and between nations.
An international organization is an organization with an international membership, scope, or presence.
The International Space Station (ISS) is a space station, or a habitable artificial satellite, in low Earth orbit.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
The invariable plane of a planetary system, also called Laplace's invariable plane, is the plane passing through its barycenter (center of mass) perpendicular to its angular momentum vector.
Iron is a chemical element with symbol Fe (from ferrum) and atomic number 26.
Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO.
Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3.
Irrigation is the application of controlled amounts of water to plants at needed intervals.
An island or isle is any piece of sub-continental land that is surrounded by water.
Isotopes are variants of a particular chemical element which differ in neutron number.
Although thorium (90Th) has 6 naturally occurring isotopes, none of these isotopes are stable; however, one isotope, 232Th, is relatively stable, with a half-life of 1.405×1010 years, considerably longer than the age of the Earth, and even slightly longer than the generally accepted age of the universe.
James Ussher (or Usher; 4 January 1581 – 21 March 1656) was the Church of Ireland Archbishop of Armagh and Primate of All Ireland between 1625 and 1656.
In Norse mythology, Jörð (Old Norse jǫrð, "earth" pronounced, Icelandic Jörð, pronounced, sometimes Anglicized as Jord or Jorth; also called Jarð, as in Old East Norse), is a female jötunn.
The Journal of African Earth Sciences is a peer-reviewed scientific journal published by Elsevier.
The Junius manuscript is one of the four major codices of Old English literature.
was a remotely operated underwater vehicle (ROV) built by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for exploration of the deep sea.
The Kármán line, or Karman line, lies at an altitude of above Earth's sea level and commonly represents the boundary between Earth's atmosphere and outer space.
The Köppen climate classification is one of the most widely used climate classification systems.
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.
The King James Version (KJV), also known as the King James Bible (KJB) or simply the Version (AV), is an English translation of the Christian Bible for the Church of England, begun in 1604 and completed in 1611.
Kitaa, originally Vestgrønland ("West Greenland"), is a former administrative division (landsdel) of Greenland.
Komatiite is a type of ultramafic mantle-derived volcanic rock.
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 landform is a natural feature of the solid surface of the Earth or other planetary body.
The term landslide or, less frequently, landslip, refers to several forms of mass wasting that include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows and debris flows.
The Laniakea Supercluster (Laniakea; also called Local Supercluster or Local SCl or sometimes Lenakaeia) is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies.
Lapse rate is the rate at which Earth's atmospheric temperature decreases with an increase in altitude, or increases with the decrease in altitude.
The last universal common ancestor (LUCA), also called the last universal ancestor (LUA), cenancestor, or (incorrectlyThere is a common misconception that definitions of LUCA and progenote are the same; however, progenote is defined as an organism “still in the process of evolving the relationship between genotype and phenotype”, and it is only hypothesed that LUCA is a progenote.) progenote, is the most recent population of organisms from which all organisms now living on Earth have a common descent.
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 increase in species richness or biodiversity that occurs from the poles to the tropics, often referred to as the latitudinal diversity gradient (LDG), is one of the most widely recognized patterns in ecology.
Lenticular clouds (Altocumulus lenticularis in Latin) are stationary clouds that form in the troposphere, typically in perpendicular alignment to the wind direction.
Life is a characteristic that distinguishes physical entities that do have biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have ceased, or because they never had such functions and are classified as inanimate.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs.
The Lindisfarne Gospels (London, British Library Cotton MS Nero D.IV) is an illuminated manuscript gospel book probably produced around the years 715-720 in the monastery at Lindisfarne, off the coast of Northumberland, which is now in the British Library in London.
A fertility deity is a god or goddess associated with sex, fertility, pregnancy, and childbirth.
This is a list of gravitationally rounded objects of the Solar System, which are objects that have a rounded, ellipsoidal shape due to the forces of their own gravity (hydrostatic equilibrium).
This is a chronological list of expeditions to the International Space Station (ISS).
This list of sovereign states provides an overview of sovereign states around the world, with information on their status and recognition of their sovereignty.
A number of polities have declared independence and sought diplomatic recognition from the international community as de jure sovereign states, but have not been universally recognised as such.
This is a list of tectonic plates on the Earth's surface.
The Local Group is the galaxy group that includes the Milky Way.
Luke 13 is the thirteenth chapter of the Gospel of Luke in the New Testament of the Christian Bible.
A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow.
In lunar calendars, a lunar month is the time between two successive syzygies (new moons or full moons).
The lunar phase or phase of the Moon is the shape of the directly sunlit portion of the Moon as viewed from Earth.
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks.
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).
The magnetic moment is a quantity that represents the magnetic strength and orientation of a magnet or other object that produces a magnetic field.
A magnetosphere is the region of space surrounding an astronomical object in which charged particles are manipulated or affected by that object's magnetic field.
Mammals are the vertebrates within the class Mammalia (from Latin mamma "breast"), a clade of endothermic amniotes distinguished from reptiles (including birds) by the possession of a neocortex (a region of the brain), hair, three middle ear bones, and mammary glands.
The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies.
Mantle convection is the slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior of the Earth to the surface.
A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle, first proposed by J. Tuzo Wilson in 1963.
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.
The Mariana Trench or Marianas Trench is the deepest part of the world's oceans.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury.
In astronomy, dynamical mass segregation is the process by which heavier members of a gravitationally bound system, such as a star cluster or cluster of galaxies, tend to move toward the center, while lighter members tend to move farther away from the center.
Matthew 28 is the twenty-eighth and final chapter of the Gospel of Matthew in the New Testament.
A medication (also referred to as medicine, pharmaceutical drug, or simply drug) is a drug used to diagnose, cure, treat, or prevent disease.
The United Nations member states are the sovereign states that are members of the United Nations (UN) and have equal representation in the UN General Assembly.
In astronomy, the meridian is the great circle passing through the celestial poles, the zenith, and the nadir of an observer's location.
The mesosphere (from Greek mesos "middle" and sphaira "sphere") is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere.
Metabolism (from μεταβολή metabolē, "change") is the set of life-sustaining chemical transformations within the cells of organisms.
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form".
In geology, metasedimentary rock is a type of metamorphic rock.
A meteoroid is a small rocky or metallic body in outer space.
Methane is a chemical compound with the chemical formula (one atom of carbon and four atoms of hydrogen).
The mica group of sheet silicate (phyllosilicate) minerals includes several closely related materials having nearly perfect basal cleavage.
A microbial mat is a multi-layered sheet of microorganisms, mainly bacteria and archaea.
A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or in a colony of cells. The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from 6th century BC India and the 1st century BC book On Agriculture by Marcus Terentius Varro. Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera and anthrax. Microorganisms include all unicellular organisms and so are extremely diverse. Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms. These were previously grouped together in the two domain system as Prokaryotes, the other being the eukaryotes. The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans. Some protists are related to animals and some to green plants. Many of the multicellular organisms are microscopic, namely micro-animals, some fungi and some algae, but these are not discussed here. They live in almost every habitat from the poles to the equator, deserts, geysers, rocks and the deep sea. Some are adapted to extremes such as very hot or very cold conditions, others to high pressure and a few such as Deinococcus radiodurans to high radiation environments. Microorganisms also make up the microbiota found in and on all multicellular organisms. A December 2017 report stated that 3.45 billion year old Australian rocks once contained microorganisms, the earliest direct evidence of life on Earth. Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel, enzymes and other bioactive compounds. They are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism. They are a vital component of fertile soils. In the human body microorganisms make up the human microbiota including the essential gut flora. They are the pathogens responsible for many infectious diseases and as such are the target of hygiene measures.
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.
A mid-ocean ridge (MOR) is an underwater mountain system formed by plate tectonics.
Middle English (ME) is collectively the varieties of the English language spoken after the Norman Conquest (1066) until the late 15th century; scholarly opinion varies but the Oxford English Dictionary specifies the period of 1150 to 1500.
The midnight sun is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the sun remains visible at the local midnight.
Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years.
The Milky Way is the galaxy that contains our Solar System.
A millisecond (from milli- and second; symbol: ms) is a thousandth (0.001 or 10−3 or 1/1000) of a second.
Mindspark Interactive Network, Inc. was an operating business unit of IAC known for the development and marketing of entertainment and personal computing software, as well as mobile application development.
Modern English (sometimes New English or NE as opposed to Middle English and Old English) is the form of the English language spoken since the Great Vowel Shift in England, which began in the late 14th century and was completed in roughly 1550.
The Mohorovičić discontinuity, usually referred to as the Moho, is the boundary between the Earth's crust and the mantle.
The Mojave Desert is an arid rain-shadow desert and the driest desert in North America.
A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H2).
Relative Molecular mass or molecular weight is the mass of a molecule.
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
A mother goddess is a goddess who represents, or is a personification of nature, motherhood, fertility, creation, destruction or who embodies the bounty of the Earth.
Mount Discovery is a conspicuous, isolated stratovolcano, lying at the head of McMurdo Sound and east of Koettlitz Glacier, overlooking the NW portion of the Ross Ice Shelf.
Mount Everest, known in Nepali as Sagarmāthā and in Tibetan as Chomolungma, is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas.
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.
The National Geospatial-Intelligence Agency (NGA) is both a combat support agency under the United States Department of Defense and an intelligence agency of the United States Intelligence Community, with the primary mission of collecting, analyzing, and distributing geospatial intelligence (GEOINT) in support of national security.
The National Institute of Standards and Technology (NIST) is one of the oldest physical science laboratories in the United States.
The National Oceanic and Atmospheric Administration (NOAA; pronounced, like "Noah") is an American scientific agency within the United States Department of Commerce that focuses on the conditions of the oceans, major waterways, and the atmosphere.
The National Science Foundation (NSF) is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering.
Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium.
Natural resources are resources that exist without actions of humankind.
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.
Nature Publishing Group is a division of the international scientific publishing company Springer Nature that publishes academic journals, magazines, online databases, and services in science and medicine.
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.
The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America.
A near-Earth object (NEO) is any small Solar System body whose orbit can bring it into proximity with Earth.
The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems).
The Neoproterozoic Era is the unit of geologic time from.
In Germanic paganism, Nerthus is a goddess associated with fertility.
Nickel is a chemical element with symbol Ni and atomic number 28.
Nitrogen is a chemical element with symbol N and atomic number 7.
Nitrous oxide, commonly known as laughing gas or nitrous, is a chemical compound, an oxide of nitrogen with the formula.
A non-renewable resource (also called a finite resource) is a resource that does not renew itself at a sufficient rate for sustainable economic extraction in meaningful human time-frames.
Norse mythology is the body of myths of the North Germanic people stemming from Norse paganism and continuing after the Christianization of Scandinavia and into the Scandinavian folklore of the modern period.
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores.
Northern Canada, colloquially the North, is the vast northernmost region of Canada variously defined by geography and politics.
The Northern Hemisphere is the half of Earth that is north of the Equator.
Nunavut (Inuktitut syllabics ᓄᓇᕗᑦ) is the newest, largest, and northernmost territory of Canada.
Nutation (from Latin nūtātiō, "nodding, swaying") is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behavior of a mechanism.
The observable universe is a spherical region of the Universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects has had time to reach Earth since the beginning of the cosmological expansion.
An ocean (the sea of classical antiquity) is a body of saline water that composes much of a planet's hydrosphere.
An ocean current is a seasonal directed movement of sea water generated by forces acting upon this mean flow, such as wind, the Coriolis effect, breaking waves, cabbing, temperature and salinity differences, while tides are caused by the gravitational pull of the Sun and Moon.
Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate.
An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides.
Oceanic trenches are topographic depressions of the sea floor, relatively narrow in width, but very long.
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.
To help compare different orders of magnitude, the following lists describe various mass levels between 10−40 kg and 1053 kg.
An ore is an occurrence of rock or sediment that contains sufficient minerals with economically important elements, typically metals, that can be economically extracted from the deposit.
Various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust.
In chemistry, an organic compound is generally any chemical compound that contains carbon.
In biology, an organism (from Greek: ὀργανισμός, organismos) is any individual entity that exhibits the properties of life.
The origin of water on Earth, or the reason that there is clearly more liquid water on Earth than on the other rocky planets of the Solar System, is not completely understood.
The Orion Arm is a minor spiral arm of the Milky Way some across and approximately in length, containing the Solar System, including the Earth.
An orogeny is an event that leads to a large structural deformation of the Earth's lithosphere (crust and uppermost mantle) due to the interaction between plate tectonics.
Orrorin tugenensis is a postulated early species of Homininae, estimated at and discovered in 2000.
The outer core of the Earth is a fluid layer about thick and composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle.
Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies.
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 following outline is provided as an overview of and topical guide to the planet Earth: Earth – third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods.
Oxford spelling (also Oxford English Dictionary spelling, Oxford style, or Oxford English spelling) is the spelling standard used by the Oxford University Press (OUP) for British publications, including its Oxford English Dictionary (OED) and its influential British style guide Hart's Rules, and by other publishers who are "etymology conscious", according to Merriam-Webster.
Oxygen is a chemical element with symbol O and atomic number 8.
Ozone, or trioxygen, is an inorganic molecule with the chemical formula.
The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation.
The ozone–oxygen cycle is the process by which ozone is continually regenerated in Earth's stratosphere, converting ultraviolet radiation (UV) into heat.
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean.
Paleontology or palaeontology is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene Epoch (roughly 11,700 years before present).
Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras.
Pannotia (from Greek: pan-, "all", -nótos, "south"; meaning "all southern land"), also known as Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent that formed at the end of the Precambrian during the Pan-African orogeny (650–500 Ma) and broke apart 560 Ma with the opening of the Iapetus Ocean.
Pedogenesis (from the Greek pedo-, or pedon, meaning 'soil, earth,' and genesis, meaning 'origin, birth') (also termed soil development, soil evolution, soil formation, and soil genesis) is the process of soil formation as regulated by the effects of place, environment, and history.
The pedosphere (from Greek πέδον pedon "soil" or "earth" and σφαῖρα sphaira "sphere") is the outermost layer of the Earth that is composed of soil and subject to soil formation processes.
The perihelion of any orbit of a celestial body about the Sun is the point where the body comes nearest to the Sun.
Petroleum is a naturally occurring, yellow-to-black liquid found in geological formations beneath the Earth's surface.
The term phase transition (or phase change) is most commonly used to describe transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma.
Phosphorus pentoxide is a chemical compound with molecular formula P4O10 (with its common name derived from its empirical formula, P2O5).
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities (energy transformation).
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.
Planet Nine is a hypothetical planet in the outer region of the Solar System.
Planetary habitability is the measure of a planet's or a natural satellite's potential to have habitable environments hospitable to life, or its ability to generate life endogenously.
Planetesimals are solid objects thought to exist in protoplanetary disks and in debris disks.
Plate tectonics (from the Late Latin tectonicus, from the τεκτονικός "pertaining to building") is a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of the Earth's lithosphere, since tectonic processes began on Earth between 3 and 3.5 billion years ago.
The Pleistocene (often colloquially referred to as the Ice Age) is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations.
PLOS Biology is a peer-reviewed scientific journal covering all aspects of Biology.
Pluto (minor planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune.
The polar climate regions are characterized by a lack of warm summers.
Polar motion of the Earth is the motion of the Earth's rotational axis relative to its crust.
The polar night occurs in the northernmost and southernmost regions of the Earth when the night lasts for more than 24 hours.
The polar regions, also called the frigid zones, of Earth are the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles.
Pollution is the introduction of contaminants into the natural environment that cause adverse change.
Potassium oxide (2O) is an ionic compound of potassium and oxygen.
Potassium-40 (40K) is a radioactive isotope of potassium which has a very long half-life of 1.251 years.
Precession is a change in the orientation of the rotational axis of a rotating body.
A pressure ridge develops in an ice cover as a result of a stress regime established within the plane of the ice.
In geochemistry, geophysics and geonuclear physics, primordial nuclides, also known as primordial isotopes, are nuclides found on Earth that have existed in their current form since before Earth was formed.
Proceedings of the National Academy of Sciences of the United States of America (PNAS) is the official scientific journal of the National Academy of Sciences, published since 1915.
Water is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, which is nearly colorless apart from an inherent hint of blue. It is by far the most studied chemical compound and is described as the "universal solvent" and the "solvent of life". It is the most abundant substance on Earth and the only common substance to exist as a solid, liquid, and gas on Earth's surface. It is also the third most abundant molecule in the universe. Water molecules form hydrogen bonds with each other and are strongly polar. This polarity allows it to separate ions in salts and strongly bond to other polar substances such as alcohols and acids, thus dissolving them. Its hydrogen bonding causes its many unique properties, such as having a solid form less dense than its liquid form, a relatively high boiling point of 100 °C for its molar mass, and a high heat capacity. Water is amphoteric, meaning that it is both an acid and a base—it produces + and - ions by self-ionization.
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.
A protoplanet is a large planetary embryo that originated within a protoplanetary disc and has undergone internal melting to produce a differentiated interior.
The pyroxenes (commonly abbreviated to Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks.
Pythagoras of Samos was an Ionian Greek philosopher and the eponymous founder of the Pythagoreanism movement.
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2.
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.
In mathematics and theoretical physics, quasiperiodic motion is in rough terms the type of motion executed by a dynamical system containing a finite number (two or more) of incommensurable frequencies.
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.
Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.
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.
Redox (short for reduction–oxidation reaction) (pronunciation: or) is a chemical reaction in which the oxidation states of atoms are changed.
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.
Rheology (from Greek ῥέω rhéō, "flow" and -λoγία, -logia, "study of") is the study of the flow of matter, primarily in a liquid state, but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force.
Rodinia (from the Russian родить, rodít, meaning "to beget, to give birth", or родина, ródina, meaning "motherland, birthplace") is a Neoproterozoic supercontinent that was assembled 1.3–0.9 billion years ago and broke up 750–633 million years ago.
A rotation is a circular movement of an object around a center (or point) of rotation.
Rudolf Simek (born 21 February 1954 in Eisenstadt, Burgenland) is an Austrian Germanist and philologist.
Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly NaCl).
Salinity is the saltiness or amount of salt dissolved in a body of water (see also soil salinity).
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) mineral particles or rock fragments.
In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit.
In various scientific contexts, a scale height is a distance over which a quantity decreases by a factor of e (approximately 2.72, the base of natural logarithms).
The Scandinavian Peninsula (Skandinaviska halvön; Den skandinaviske halvøy; Skandinavian niemimaa; ?; Скандинавский полуостров, Skandinavsky poluostrov) is a peninsula of Eurasia located in Northern Europe, which generally comprises the mainland of Sweden, the mainland of Norway (with the exception of a small coastal area bordering Russia), the northwestern area of Finland, as well as a narrow area in the west of the Pechengsky District of Russia.
Scientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study.
The Scotia Plate is a tectonic plate on the edge of the South Atlantic and Southern Ocean.
Mean sea level (MSL) (often shortened to sea level) is an average level of the surface of one or more of Earth's oceans from which heights such as elevations may be measured.
A sea level rise is an increase in global mean sea level as a result of an increase in the volume of water in the world’s oceans.
A season is a division of the year marked by changes in weather, ecology, and amount of daylight.
The secular variation of a time series is its long-term non-periodic variation (see Decomposition of time series).
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water.
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter.
A shrew (family Soricidae) is a small mole-like mammal classified in the order Eulipotyphla.
Sidereal time is a timekeeping system that astronomers use to locate celestial objects.
A sidereal year (from Latin sidus "asterism, star") is the time taken by the Earth to orbit the Sun once with respect to the fixed stars.
Silicate minerals are rock-forming minerals with predominantly silicate anions.
Silicon is a chemical element with symbol Si and atomic number 14.
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.
A sinkhole, also known as a cenote, sink, sink-hole, swallet, swallow hole, or doline (the different terms for sinkholes are often used interchangeably), is a depression or hole in the ground caused by some form of collapse of the surface layer.
The Snowball Earth hypothesis proposes that Earth surface's became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya (million years ago).
A society is a group of individuals involved in persistent social interaction, or a large social group sharing the same geographical or social territory, typically subject to the same political authority and dominant cultural expectations.
Sodium oxide is a chemical compound with the formula Na2O.
Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life.
Soil fertility refers to the ability of a soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.
Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable soil.
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.
Solar irradiance is the power per unit area received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument.
The solar luminosity,, is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun.
The Solar SystemCapitalization of the name varies.
Solar time is a calculation of the passage of time based on the position of the Sun in the sky.
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona.
In geometry, a solid angle (symbol) is a measure of the amount of the field of view from some particular point that a given object covers.
A solstice is an event occurring when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere.
The Somali Plate, or Somalian Plate, is a minor tectonic plate, which straddles the equator in the eastern hemisphere.
The South American Plate is a tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the African Plate creating the Mid-Atlantic Ridge The easterly side is a divergent boundary with the African Plate forming the southern part of the Mid-Atlantic Ridge.
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 Southern Hemisphere is the half of Earth that is south of the Equator.
Sovereignty is the full right and power of a governing body over itself, without any interference from outside sources or bodies.
Space debris (also known as space junk, space waste, space trash, space litter or space garbage) is a term for the mass of defunct, artificially created objects in space, most notably in Earth orbit, such as old satellites and spent rocket stages.
Space.com is a space and astronomy news website.
In biology, a species is the basic unit of classification and a taxonomic rank, as well as a unit of biodiversity, but it has proven difficult to find a satisfactory definition.
The earliest reliably documented mention of the spherical Earth concept dates from around the 6th century BC when it appeared in ancient Greek philosophy but remained a matter of speculation until the 3rd century BC, when Hellenistic astronomy established the spherical shape of the Earth as a physical given.
A spheroid, or ellipsoid of revolution, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters.
Stellar evolution is the process by which a star changes over the course of time.
The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere.
A style guide (or manual of style) is a set of standards for the writing and design of documents, either for general use or for a specific publication, organization, or field.
Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced or sinks due to gravity into the mantle.
A submarine canyon is a steep-sided valley cut into the seabed of the continental slope, sometimes extending well onto the continental shelf, having nearly vertical walls, and occasionally having canyon wall heights of up to 5 km, from canyon floor to canyon rim, as with the Great Bahama Canyon.
A substorm, sometimes referred to as a magnetospheric substorm or an auroral substorm, is a brief disturbance in the Earth's magnetosphere that causes energy to be released from the "tail" of the magnetosphere and injected into the high latitude ionosphere.
The subtropics are geographic and climate zones located roughly between the tropics at latitude 23.5° (the Tropic of Cancer and Tropic of Capricorn) and temperate zones (normally referring to latitudes 35–66.5°) north and south of the Equator.
Sulfur or sulphur is a chemical element with symbol S and atomic number 16.
Summer is the hottest of the four temperate seasons, falling after spring and before autumn.
The summer solstice (or estival solstice), also known as midsummer, occurs when one of the Earth's poles has its maximum tilt toward the Sun.
The Sun is the star at the center of the Solar System.
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass.
Surveying or land surveying is the technique, profession, and science of determining the terrestrial or three-dimensional positions of points and the distances and angles between them.
Symbiogenesis, or endosymbiotic theory, is an evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn Margulis in 1967.
Publius (or Gaius) Cornelius Tacitus (–) was a senator and a historian of the Roman Empire.
In geography, the temperate or tepid climates of Earth occur in the middle latitudes, which span between the tropics and the polar regions of Earth.
A terminator or twilight zone is a moving line that divides the daylit side and the dark night side of a planetary body.
Terra is the Latin name for Earth.
In ancient Roman religion and myth, Tellus Mater or Terra Mater ("Mother Earth") is a goddess of the earth.
Terra nullius (plural terrae nullius) is a Latin expression meaning "nobody's land", and is a principle sometimes used in international law to describe territory that may be acquired by a state's occupation of it.
Terrain or relief (also topographical relief) involves the vertical and horizontal dimensions of land surface.
A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals.
The tesla (symbol T) is a derived unit of magnetic flux density (informally, magnetic field strength) in the International System of Units.
The Alcalde has been the alumni magazine of The University of Texas at Austin since 1913, and is published by the university's alumni association, the Texas Exes.
The Blue Marble is an image of planet Earth made on December 7, 1972, by the crew of the Apollo 17 spacecraft at a distance of about from the surface.
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 Rise and Fall of the Great Powers: Economic Change and Military Conflict from 1500 to 2000, by Paul Kennedy, first published in 1987, explores the politics and economics of the Great Powers from 1500 to 1980 and the reason for their decline.
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.
Thermal energy is a term used loosely as a synonym for more rigorously-defined thermodynamic quantities such as the internal energy of a system; heat or sensible heat, which are defined as types of transfer of energy (as is work); or for the characteristic energy of a degree of freedom in a thermal system kT, where T is temperature and k is the Boltzmann constant.
A thermal reservoir, a short-form of thermal energy reservoir, or thermal bath is a thermodynamic system with a heat capacity that is large enough that when it is in thermal contact with another system of interest or its environment, its temperature remains effectively constant.
Thermodynamics is the branch of physics concerned with heat and temperature and their relation to energy and work.
Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.
The thermosphere is the layer of the Earth's atmosphere directly above the mesosphere and below the exosphere.
In Norse mythology, Thor (from Þórr) is the hammer-wielding god of thunder, lightning, storms, oak trees, strength, the protection of mankind, in addition to hallowing, and fertility.
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).
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.
This timeline of natural history summarizes significant geological and biological events from the formation of the Earth to the arrival of modern humans.
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 tonne (Non-SI unit, symbol: t), commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms;.
Topography is the study of the shape and features of the surface of the Earth and other observable astronomical objects including planets, moons, and asteroids.
Topsoil is the upper, outermost layer of soil, usually the top to.
A tornado is a rapidly rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud.
Torque, moment, or moment of force is rotational force.
The trade winds are the prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere, in the lower section of the troposphere near the Earth's equator.
A transform fault or transform boundary is a plate boundary where the motion is predominantly horizontal.
The transition zone is part of the Earth’s mantle, and is located between the lower mantle and the upper mantle, between a depth of 410 and 660 km (250 to 400 mi).
The Tropic of Cancer, also referred to as the Northern Tropic, is the most northerly circle of latitude on Earth at which the Sun can be directly overhead.
The Tropic of Capricorn (or the Southern Tropic) is the circle of latitude that contains the subsolar point on the December (or southern) solstice.
A tropical climate in the Köppen climate classification is a non-arid climate in which all twelve months have mean temperatures of at least.
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain.
Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforest.
A tropical year (also known as a solar year) is the time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice.
The tropics are a region of the Earth surrounding the Equator.
The troposphere is the lowest layer of Earth's atmosphere, and is also where nearly all weather conditions take place.
A tsunami (from 津波, "harbour wave"; English pronunciation) or tidal wave, also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake.
In physical geography, tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons.
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists.
A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere.
Ultraviolet (UV) is electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.
The Union of Concerned Scientists (UCS) is a nonprofit science advocacy organization based in the United States.
The United Nations (UN) is an intergovernmental organization tasked to promote international cooperation and to create and maintain international order.
In addition to its UNnum member states, the United Nations General Assembly may grant observer status to an international organization, entity or non-member state, which entitles the entity to participate in the work of the United Nations General Assembly, though with limitations.
The United States Department of Commerce is the Cabinet department of the United States government concerned with promoting economic growth.
The United States Geological Survey (USGS, formerly simply Geological Survey) is a scientific agency of the United States government.
The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
The University of Wisconsin–Madison (also known as University of Wisconsin, Wisconsin, UW, or regionally as UW–Madison, or simply Madison) is a public research university in Madison, Wisconsin, United States.
Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%.
A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a planet by that planet's magnetic field.
Vanguard 1 (ID: 1958-Beta 2) was the fourth artificial Earth orbital satellite to be successfully launched (following Sputnik 1, Sputnik 2, and Explorer 1).
The Vector Map (VMAP), also called Vector Smart Map, is a vector-based collection of geographic information system (GIS) data about Earth at various levels of detail.
The Virgo Supercluster (Virgo SC) or the Local Supercluster (LSC or LS) is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which in turn contains the Milky Way and Andromeda galaxies.
The viscosity of a fluid is the measure of its resistance to gradual deformation by shear stress or tensile stress.
Volcanism is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent.
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.
Vostok Station (translit,, literally "Station East") is a Russian research station in inland Princess Elizabeth Land, Antarctica.
Water is a transparent, tasteless, odorless, and nearly colorless chemical substance that is the main constituent of Earth's streams, lakes, and oceans, and the fluids of most living organisms.
The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth.
Water is distributed across earth.
Weathering is the breaking down of rocks, soil, and minerals as well as wood and artificial materials through contact with the Earth's atmosphere, water, and biological organisms.
The Wessex Gospels (also known as the West-Saxon Gospels) are a full translation of the four gospels of the Christian Bible into a West Saxon dialect of Old English and one of several Old English Bible translations.
The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude.
Western Australia (abbreviated as WA) is a state occupying the entire western third of Australia.
A wildfire or wildland fire is a fire in an area of combustible vegetation that occurs in the countryside or rural area.
William Thomson, 1st Baron Kelvin, (26 June 1824 – 17 December 1907) was a Scots-Irish mathematical physicist and engineer who was born in Belfast in 1824.
Wind is the flow of gases on a large scale.
Winter is the coldest season of the year in polar and temperate zones (winter does not occur in the tropical zone).
The winter solstice (or hibernal solstice), also known as midwinter, is an astronomical phenomenon marking the day with the shortest period of daylight and the longest night of the year.
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants.
The World Geodetic System (WGS) is a standard for use in cartography, geodesy, and satellite navigation including GPS.
The World Meteorological Organization (WMO) is an intergovernmental organization with a membership of 191 Member States and Territories.
In demographics, the world population is the total number of humans currently living, and was estimated to have reached 7.6 billion people as of May 2018.
Yale University Press is a university press associated with Yale University.
A year is the orbital period of the Earth moving in its orbit around the Sun.
Yuri Alekseyevich Gagarin (p; 9 March 1934 – 27 March 1968) was a Soviet pilot and cosmonaut.
The terms zonal and meridional are used to describe directions on a globe.
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.
806.4616.0110, Blue and green planet, Composition of the Earth, EARTH, Eaht, Eareth, Earf, EartH, Earth (Planet), Earth (planet), Earth (word), Earth's mean density, Earth's surface, Earth, Sol, Earth’s surface, Etymology of the word "Earth", Formation of the Earth, Globe (Earth), Green and blue planet, Home Planet, Lexicography of Earth, Local Planet, Main shock, Mainshock, Mean density of the Earth, Planet Earth, Planet Terra, Planet earth, Planet of Water, Sol 3, Sol III, Sol Prime, Sol d, Sol-3, Sun d, Surface area of earth, Surface of the Earth, Telluris, Tellus (Planet), Terra (Planetry Science), Terra (name for the earth), Terra (planet), The Earth, The Planet Earth, The planet Earth, The planet earth, Third Planet, Third planet from the Sun, Tierra (planet), Whole World, World (geography), 🌏.