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184-427: Apart from the global continental regions, there are also hydrospheric and atmospheric regions that cover the oceans , and discrete climates above the land and water masses of the planet. The land and water global regions are divided into subregions geographically bounded by large geological features that influence large-scale ecologies, such as plains and features. As a way of describing spatial areas,

368-761: A Field Marshal or General of the Army (US five stars), or Generalissimo (Soviet Union); and in the US Armed Forces an Admiral (typically four stars) may also command a region. Due to the large size of this formation, its use is rarely employed. Some of the very few examples of an Army Region are each of the Eastern, Western, and southern (mostly in Italy) fronts in Europe during World War II . The military map unit symbol for this echelon of formation (see Military organization and APP-6A )

552-533: A circumstellar disk , and then the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides ). According to nebular theory , planetesimals formed by accretion , with the primordial Earth being estimated as likely taking anywhere from 70 to 100 million years to form. Estimates of the age of the Moon range from 4.5 Ga to significantly younger. A leading hypothesis

736-462: A 'Ba Jun Tu Jing' ('Map of Sichuan'), which had been made much earlier in 150. The Shui Jing ( Waterways Classic ) was written anonymously in the 3rd century during the Three Kingdoms era (attributed often to Guo Pu ), and gave a description of some 137 rivers found throughout China. In the 6th century, the book was expanded to forty times its original size by the geographers Li Daoyuan , given

920-600: A carefully structured picture of the cosmos. He corrects his sources and writes more scientifically, whereas Basil's Hexaemeron is theological in style. Karl Müller has collected and printed several anonymous works of geography from this era, including the Expositio totius mundi . In the latter 7th century, adherents of the new religion of Islam surged northward out of Arabia taking over lands in which Jews , Byzantine Christians and Persian Zoroastrians had been established for centuries. There, carefully preserved in

1104-579: A clear picture of the status of geographical knowledge of the time. Pliny the Elder 's (AD 23 – 79) Natural History also has sections on geography. A century after Strabo Ptolemy (AD 90 – 168) launched a similar undertaking. By this time the Roman Empire had expanded through much of Europe, and previously unknown areas such as the British Isles had been explored. The Silk Road was also in operation, and for

1288-492: A common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month , from new moon to new moon, is 29.53 days. Viewed from the celestial north pole , the motion of Earth, the Moon, and their axial rotations are all counterclockwise . Viewed from a vantage point above the Sun and Earth's north poles, Earth orbits in

1472-542: A counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic ), and the Earth-Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses . The Hill sphere , or

1656-404: A country or the world having definable characteristics but not always fixed boundaries. In the fields of physical geography , ecology , biogeography , zoogeography , and environmental geography , regions tend to be based on natural features such as ecosystems or biotopes , biomes , drainage basins , natural regions , mountain ranges , soil types . Where human geography is concerned,

1840-638: A cultural region. Examples of natural resource regions are the Rumaila Field , the oil field that lies along the border or Iraq and Kuwait and played a role in the Gulf War ; the Coal Region of Pennsylvania, which is a historical region as well as a cultural, physical, and natural resource region; the South Wales Coalfield , which like Pennsylvania's coal region is a historical, cultural, and natural region;

2024-462: A department of the Roman government devoted to transportation, employed full-time gromatici ( surveyors ). The surveyors' job was to gather topographical information and then to determine the straightest possible route where a road might be built. Instruments and principles used included sun dials for determining direction, theodolites for measuring horizontal angles, and triangulation without which

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2208-420: A full rotation about its axis so that the Sun returns to the meridian . The orbital speed of Earth averages about 29.78 km/s (107,200 km/h; 66,600 mph), which is fast enough to travel a distance equal to Earth's diameter, about 12,742 km (7,918 mi), in seven minutes, and the distance from Earth to the Moon, 384,400 km (238,900 mi), in about 3.5 hours. The Moon and Earth orbit

2392-415: A functional region. Nodal regions, functional urban regions, daily urban systems, local labour-market areas (LLMAs), or travel-to-work areas (TTWAs) are considered to be special instances of a general functional region that need to fulfil some specific conditions regarding, for instance, the character of the region-organising interaction or the presence of urban cores, (Halas et al., 2015). In military usage,

2576-556: A geographical section, which was often an enormous compilation of changes in place-names and local administrative divisions controlled by the ruling dynasty, descriptions of mountain ranges, river systems, taxable products, etc. The ancient Chinese historian Ban Gu (32–92) most likely started the trend of the gazetteer in China, which became prominent in the Northern and Southern dynasties period and Sui dynasty . Local gazetteers would feature

2760-421: A globe-spanning mid-ocean ridge system. At Earth's polar regions , the ocean surface is covered by seasonally variable amounts of sea ice that often connects with polar land, permafrost and ice sheets , forming polar ice caps . Earth's land covers 29.2%, or 149 million km (58 million sq mi) of Earth's surface. The land surface includes many islands around the globe, but most of

2944-552: A globe. This has been debated widely as being dismissive of the extensive Native American history that predated the 16th-century invasion, in the sense that the implication of a "birth certificate" implies a blank history prior. Geography as a science experiences excitement and exerts influence during the Scientific revolution and Reformation . In the Victorian period, the oversea exploration gave it institutional identity and geography

3128-465: A late 10th-century Persian geographer, accompanied a book of geographical coordinates with instructions for making a rectangular world map, with equirectangular projection or cylindrical equidistant projection. In the early 11th century, Avicenna hypothesized on the geological causes of mountains in The Book of Healing (1027). In mathematical geography, Persian Abū Rayhān al-Bīrūnī , around 1025,

3312-522: A lesser degree, regions in the sphere of influence of Greater New England, "Acadia" (Nova Scotia), "Newfoundland and The Fishery/The Banks". Other examples of historical regions are Iroquoia, Ohio Country , Illinois Country , and Rupert's Land . In Russia , historical regions include Siberia and the Russian North , as well as the Ural Mountains . These regions had an identity that developed from

3496-500: A number of countries have borrowed the term as the formal name for a type of subnational entity (e.g., the región , used in Chile ). In English, the word is also used as the conventional translation for equivalent terms in other languages (e.g., the область ( oblast ), used in Russia alongside a broader term регион ). The following countries use the term "region" (or its cognate ) as

3680-604: A range of geographical and statistical information about the various regions of India. The composers of the Puranas divided the known world into seven continents of dwipas, Jambu Dwipa, Krauncha Dwipa, Kusha Dwipa, Plaksha Dwipa, Pushkara Dwipa, Shaka Dwipa and Shalmali Dwipa. Descriptions were provided for the climate and geography of each of the dwipas. The Vishnudharmottara Purana (compiled between 300 and 350 AD) contains six chapters on physical and human geography. The locational attributes of peoples and places, and various seasons are

3864-508: A region far from where bamboo was suitable to grow. The 14th-century Yuan dynasty geographer Na-xin wrote a treatise of archeological topography of all the regions north of the Yellow River, in his book He Shuo Fang Gu Ji . The Ming dynasty geographer Xu Xiake (1587–1641) traveled throughout the provinces of China (often on foot) to write his enormous geographical and topographical treatise, documenting various details of his travels, such as

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4048-417: A region is shorthand for the name of a military formation larger than an Army Group and smaller than a Theater . The full name of the military formation is Army Region. The size of an Army Region can vary widely but is generally somewhere between about 1 million and 3 million soldiers. Two or more Army Regions could make up a Theater. An Army Region is typically commanded by a full General (US four stars),

4232-403: A scale map of the known world and to have introduced the gnomon to Ancient Greece. Hecataeus of Miletus initiated a different form of geography, avoiding the mathematical calculations of Thales and Anaximander he learnt about the world by gathering previous works and speaking to the sailors who came through the busy port of Miletus. From these accounts he wrote a detailed prose account of what

4416-529: A significant percentage of their respective continental land area. To a large extent, major continental regions are mental constructs created by considering an efficient way to define large areas of the continents. For the most part, the images of the world are derived as much from academic studies, from all types of media, or from personal experience of global exploration . They are a matter of collective human knowledge of their own planet and are attempts to better understand their environments. Regional geography

4600-651: A similar way, as does Romania and Venezuela . The government of Singapore makes use of the term " region " for its own administrative purposes. The following countries use an administrative subdivision conventionally referred to as a region in English: China has five 自治区 ( zìzhìqū ) and two 特別行政區 (or 特别行政区; tèbiéxíngzhèngqū ), which are translated as " autonomous region " and " special administrative region ", respectively. There are many relatively small regions based on local government agencies such as districts, agencies, or regions. In general, they are all regions in

4784-611: A sort of social and political polity . The term Muslim world is sometimes used to refer to the region of the world where Islam is dominant. These broad terms are somewhat vague when used to describe regions. Within some religions there are clearly defined regions. The Roman Catholic Church , the Church of England , the Eastern Orthodox Church , and others, define ecclesiastical regions with names such as diocese , eparchy , ecclesiastical provinces , and parish . For example,

4968-461: A state of affairs that would persist until the 13th century. The earliest extant maps found in archeological sites of China date to the 4th century BC and were made in the ancient State of Qin . The earliest known reference to the application of a geometric grid and mathematically graduated scale to a map was contained in the writings of the cartographer Pei Xiu (224–271). From the 1st century AD onwards, official Chinese historical texts contained

5152-454: A vast amount of scholarship has gone into trying to link Ptolemaic descriptions to known locations. It was the Romans who made far more extensive practical use of geography and maps. The Roman transportation system , consisting of 55,000 miles (89,000 km) of roads, could not have been designed without the use of geographical systems of measurement and triangulation . The cursus publicus ,

5336-515: A wealth of geographic information, although its cartographic aspects were not as highly professional as the maps created by professional cartographers. From the time of the 5th century BC Shu Jing forward, Chinese geographical writing provided more concrete information and less legendary element. This example can be seen in the 4th chapter of the Huainanzi (Book of the Master of Huainan), compiled under

5520-613: A wealth of geographical information. Chinese geographers such as Jia Dan (730–805) wrote accurate descriptions of places far abroad. In his work written between 785 and 805, he described the sea route going into the mouth of the Persian Gulf , and that the medieval Iranians (whom he called the people of the Luo-He-Yi country, i.e. Persia ) had erected 'ornamental pillars' in the sea that acted as lighthouse beacons for ships that might go astray. Confirming Jia's reports about lighthouses in

5704-450: Is a branch of geography that studies regions of all sizes across the Earth . It has a prevailing descriptive character. The main aim is to understand or define the uniqueness or character of a particular region, which consists of natural as well as human elements. Attention is paid also to regionalization, which covers the proper techniques of space delimitation into regions. Regional geography

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5888-456: Is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity . The thickness of the crust varies from about 6 kilometres (3.7 mi) under the oceans to 30–50 km (19–31 mi) for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as

6072-600: Is a popular misconception that they thought the world was flat), and the simple T and O map became the standard depiction of the world. The trips of Venetian explorer Marco Polo throughout Mongol Empire in the 13th century, the Christian Crusades of the 12th and 13th centuries, and the Portuguese and Spanish voyages of exploration during the 15th and 16th centuries opened up new horizons and stimulated geographic writings. The Mongols also had wide-ranging knowledge of

6256-432: Is actually being referred to. Thales of Miletus is one of the first known philosophers known to have wondered about the shape of the world. He proposed that the world was based on water, and that all things grew out of it. He also laid down many of the astronomical and mathematical rules that would allow geography to be studied scientifically. His successor Anaximander is the first person known to have attempted to create

6440-477: Is also considered as a certain approach to study in geographical sciences (similar to quantitative or critical geographies ; for more information, see history of geography ). Human geography is a branch of geography that focuses on the study of patterns and processes that shape human interaction with various discrete environments. It encompasses human , political , cultural , social , and economic aspects among others that are often clearly delineated. While

6624-531: Is approximately 9.8 m/s (32 ft/s ). Local differences in topography, geology, and deeper tectonic structure cause local and broad regional differences in Earth's gravitational field, known as gravity anomalies . The main part of Earth's magnetic field is generated in the core, the site of a dynamo process that converts the kinetic energy of thermally and compositionally driven convection into electrical and magnetic field energy. The field extends outwards from

6808-435: Is at least somewhat humid and covered by vegetation , while large sheets of ice at Earth's polar deserts retain more water than Earth's groundwater , lakes, rivers and atmospheric water combined. Earth's crust consists of slowly moving tectonic plates , which interact to produce mountain ranges, volcanoes , and earthquakes. Earth has a liquid outer core that generates a magnetosphere capable of deflecting most of

6992-517: Is contained in 3.45 billion-year-old Australian rocks showing fossils of microorganisms . During the Neoproterozoic , 1000 to 539 Ma , much of Earth might have been covered in ice. This hypothesis has been termed " Snowball Earth ", and it is of particular interest because it preceded the Cambrian explosion , when multicellular life forms significantly increased in complexity. Following

7176-699: Is currently a controversial proposal to divide the rest of Sweden into large regions , replacing the current counties. The government of the Philippines uses the term "region" (in Filipino , rehiyon ) when it is necessary to group provinces, the primary administrative subdivision of the country. This is also the case in Brazil , which groups its primary administrative divisions ( estados ; "states") into grandes regiões ( greater regions ) for statistical purposes, while Russia uses экономические районы ( economic regions ) in

7360-759: Is currently kept in South Korea. See also: Maps of the Yuan Dynasty During the 15th century, Henry the Navigator of Portugal supported explorations of the African coast and became a leader in the promotion of geographic studies. Among the most notable accounts of voyages and discoveries published during the 16th century were those by Giambattista Ramusio in Venice, by Richard Hakluyt in England, and by Theodore de Bry in what

7544-452: Is farthest out from its center of mass at its equatorial bulge, the summit of the volcano Chimborazo in Ecuador (6,384.4 km or 3,967.1 mi) is its farthest point out. Parallel to the rigid land topography the ocean exhibits a more dynamic topography . To measure the local variation of Earth's topography, geodesy employs an idealized Earth producing a geoid shape. Such a shape

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7728-516: Is gained if the ocean is idealized, covering Earth completely and without any perturbations such as tides and winds. The result is a smooth but irregular geoid surface, providing a mean sea level (MSL) as a reference level for topographic measurements. Earth's surface is the boundary between the atmosphere, and the solid Earth and oceans. Defined in this way, it has an area of about 510 million km (197 million sq mi). Earth can be divided into two hemispheres : by latitude into

7912-437: Is giving spatial understanding of mediated image. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Earth Earth

8096-421: Is identified with six Xs. Media geography is a spatio-temporal understanding, brought through different gadgets of media, nowadays, media became inevitable at different proportions and everyone supposed to consumed at different gravity. The spatial attributes are studied with the help of media outputs in shape of images which are contested in nature and pattern as well where politics is inseparable. Media geography

8280-432: Is not an abstract spatial concept, but to a certain extent it can be regarded as a reflection of the spatial behaviour of individuals in a geographic space. The functional region is conceived as a general concept while its inner structure, inner spatial flows, and interactions need not necessarily show any regular pattern, only selfcontainment. The concept of self-containment remains the only crucial defining characteristic of

8464-448: Is now Belgium. Following the journeys of Marco Polo , interest in geography spread throughout Europe. From around c. 1400, the writings of Ptolemy and his successors provided a systematic framework to tie together and portray geographical information. This framework was used by academics for centuries to come, the positives being the lead-up to the geographical enlightenment, however, women and indigenous writings were largely excluded from

8648-501: Is now slightly longer than it was during the 19th century due to tidal deceleration , each day varies between 0 and 2 ms longer than the mean solar day. Earth's rotation period relative to the fixed stars , called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is 86,164.0989 seconds of mean solar time ( UT1 ), or 23 56 4.0989 . Earth's rotation period relative to

8832-560: Is of enormous value, providing well-referenced geographical and other information about ancient Greece . The geographer Hierocles (6th century) authored the Synecdemus (prior to AD 535) in which he provides a table of administrative divisions of the Byzantine Empire and lists the cities in each. The Synecdemus and the Ethnica were the principal sources of Constantine VII 's work on

9016-612: Is rare, though the alternative spelling Gaia has become common due to the Gaia hypothesis , in which case its pronunciation is / ˈ ɡ aɪ . ə / rather than the more classical English / ˈ ɡ eɪ . ə / . There are a number of adjectives for the planet Earth. The word "earthly" is derived from "Earth". From the Latin Terra comes terran / ˈ t ɛr ə n / , terrestrial / t ə ˈ r ɛ s t r i ə l / , and (via French) terrene / t ə ˈ r iː n / , and from

9200-477: Is that it was formed by accretion from material loosed from Earth after a Mars -sized object with about 10% of Earth's mass, named Theia , collided with Earth. It hit Earth with a glancing blow and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Ga , numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of

9384-453: Is the basis for the astronomical unit (AU) and is equal to roughly 8.3 light minutes or 380 times Earth's distance to the Moon . Earth orbits the Sun every 365.2564 mean solar days , or one sidereal year . With an apparent movement of the Sun in Earth's sky at a rate of about 1°/day eastward, which is one apparent Sun or Moon diameter every 12 hours. Due to this motion, on average it takes 24 hours—a solar day—for Earth to complete

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9568-580: Is the third planet from the Sun and the only astronomical object known to harbor life . This is enabled by Earth being an ocean world , the only one in the Solar System sustaining liquid surface water . Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust . The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere . Most of Earth's land

9752-457: Is tied to that of the Sun. Over the next 1.1 billion years , solar luminosity will increase by 10%, and over the next 3.5 billion years by 40%. Earth's increasing surface temperature will accelerate the inorganic carbon cycle , possibly reducing CO 2 concentration to levels lethally low for current plants ( 10  ppm for C4 photosynthesis ) in approximately 100–900 million years . A lack of vegetation would result in

9936-523: The Odyssey are works of literature, but both contain a great deal of geographical information. Homer describes a circular world ringed by a single massive ocean. The works show that the Greeks by the 8th century BC had considerable knowledge of the geography of the eastern Mediterranean. The poems contain a large number of place names and descriptions, but for many of these it is uncertain what real location, if any,

10120-775: The Byzantine or Eastern Roman Empire . Cosmas Indicopleustes , (6th century) also known as "Cosmas the Monk", was an Alexandrian merchant . By the records of his travels, he seems to have visited India, Sri Lanka , the Kingdom of Axum in modern Ethiopia , and Eritrea . Included in his work Christian Topography were some of the earliest world maps . Though Cosmas believed the earth to be flat, most Christian geographers of his time disagreed with him. Syrian bishop Jacob of Edessa (633–708) adapted scientific material sourced from Aristotle , Theophrastus , Ptolemy and Basil to develop

10304-807: The Grand Banks . He rejects regions traditionally used in describing American history, like New France , "West Indies", the Middle Colonies , and the individual colonies themselves ( Province of Maryland , for example). Instead he writes of "discrete colonization areas", which may be named after colonies but rarely adhere strictly to political boundaries. Among other historic regions of this type, he writes about "Greater New England" and its major sub-regions of "Plymouth", "New Haven shores" (including parts of Long Island), "Rhode Island" (or "Narragansett Bay"), "the Piscataqua", "Massachusetts Bay", "Connecticut Valley", and to

10488-539: The Kuznetsk Basin , a similarly important coal mining region in Russia; Kryvbas , the economic and iron ore mining region of Ukraine; and the James Bay Project , a large region of Quebec where one of the largest hydroelectric systems in the world has been developed. Sometimes a region associated with a religion is given a name, like Christendom , a term with medieval and renaissance connotations of Christianity as

10672-979: The Metropolitan Water Reclamation District of Greater Chicago , the Las Vegas-Clark County Library District , the Metropolitan Police Service of Greater London , as well as other local districts like the York Rural Sanitary District , the Delaware River Port Authority , the Nassau County Soil and Water Conservation District , and C-TRAN . The traditional territorial divisions of some countries are also commonly rendered in English as "regions". These informal divisions do not form

10856-566: The Milky Way and orbits about 28,000  light-years from its center. It is about 20 light-years above the galactic plane in the Orion Arm . The axial tilt of Earth is approximately 23.439281° with the axis of its orbit plane, always pointing towards the Celestial Poles . Due to Earth's axial tilt, the amount of sunlight reaching any given point on the surface varies over the course of

11040-493: The Norman King Roger II , having great interest in geography, commissioned the creation of a book and map that would compile all this wealth of geographical information. Researchers were sent out and the collection of data took 15 years. Al-Idrisi , one of few Arabs who had ever been to France and England as well as Spain, Central Asia and Constantinople, was employed to create the book from this mass of data. Utilizing

11224-553: The Northwest European Atlantic Protestant Region , which includes sub-regions such as the "Western Channel Community", which itself is made of sub-regions such as the English West Country of Cornwall , Devon , Somerset , and Dorset . In describing historic regions of America, Meinig writes of "The Great Fishery" off the coast of Newfoundland and New England, an oceanic region that includes

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11408-722: The Pacific , North American , Eurasian , African , Antarctic , Indo-Australian , and South American . Other notable plates include the Arabian Plate , the Caribbean Plate , the Nazca Plate off the west coast of South America and the Scotia Plate in the southern Atlantic Ocean. The Australian Plate fused with the Indian Plate between 50 and 55 Ma . The fastest-moving plates are

11592-497: The Themes or divisions of Byzantium , and are the primary sources we have today on political geography of the sixth-century East. George of Cyprus is known for his Descriptio orbis Romani (Description of the Roman world) , written in the decade 600–610. Beginning with Italy and progressing counterclockwise including Africa , Egypt and the western Middle East , George lists cities, towns, fortresses and administrative divisions of

11776-506: The United Kingdom 's Lake District and California's Wine Country . great plains region Natural resources often occur in distinct regions. Natural resource regions can be a topic of physical geography or environmental geography, but also have a strong element of human geography and economic geography. A coal region, for example, is a physical or geomorphological region, but its development and exploitation can make it into an economic and

11960-419: The asthenosphere , the solid but less-viscous part of the upper mantle that can flow and move along with the plates. As the tectonic plates migrate, oceanic crust is subducted under the leading edges of the plates at convergent boundaries. At the same time, the upwelling of mantle material at divergent boundaries creates mid-ocean ridges. The combination of these processes recycles the oceanic crust back into

12144-415: The celestial equator , this is equivalent to an apparent diameter of the Sun or the Moon every two minutes; from Earth's surface, the apparent sizes of the Sun and the Moon are approximately the same. Earth orbits the Sun, making Earth the third-closest planet to the Sun and part of the inner Solar System . Earth's average orbital distance is about 150 million km (93 million mi), which

12328-410: The equatorial region receiving more sunlight than the polar regions) drive atmospheric and ocean currents , producing a global climate system with different climate regions , and a range of weather phenomena such as precipitation , allowing components such as nitrogen to cycle . Earth is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in

12512-408: The ocean floor form the top of Earth's crust , which together with parts of the upper mantle form Earth's lithosphere . Earth's crust may be divided into oceanic and continental crust. Beneath the ocean-floor sediments, the oceanic crust is predominantly basaltic , while the continental crust may include lower density materials such as granite , sediments and metamorphic rocks. Nearly 75% of

12696-430: The precessing or moving mean March equinox (when the Sun is at 90° on the equator), is 86,164.0905 seconds of mean solar time (UT1) (23 56 4.0905 ) . Thus the sidereal day is shorter than the stellar day by about 8.4 ms. Apart from meteors within the atmosphere and low-orbiting satellites, the main apparent motion of celestial bodies in Earth's sky is to the west at a rate of 15°/h = 15'/min. For bodies near

12880-468: The sphere of gravitational influence , of Earth is about 1.5 million km (930,000 mi) in radius. This is the maximum distance at which Earth's gravitational influence is stronger than that of the more distant Sun and planets. Objects must orbit Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System, is situated in

13064-426: The topography of the land, along with the agricultural, economic and commercial products of each region in China's southern provinces. The polymath Chinese scientist Shen Kuo (1031–1095) devoted a significant amount of his written work to geography, as well as a hypothesis of land formation ( geomorphology ) due to the evidence of marine fossils found far inland, along with bamboo fossils found underground in

13248-464: The "last ice age", covered large parts of the continents, to the middle latitudes, in ice and ended about 11,700 years ago. Chemical reactions led to the first self-replicating molecules about four billion years ago. A half billion years later, the last common ancestor of all current life arose. The evolution of photosynthesis allowed the Sun's energy to be harvested directly by life forms. The resultant molecular oxygen ( O 2 ) accumulated in

13432-553: The 9th century BC. The best known Babylonian world map, however, is the Imago Mundi of 600 BC. The map as reconstructed by Eckhard Unger shows Babylon on the Euphrates , surrounded by a circular landmass showing Assyria , Urartu and several cities, in turn surrounded by a "bitter river" ( Oceanus ), with seven islands arranged around it so as to form a seven-pointed star. The accompanying text mentions seven outer regions beyond

13616-479: The Cambrian explosion, 535 Ma , there have been at least five major mass extinctions and many minor ones. Apart from the proposed current Holocene extinction event, the most recent was 66 Ma , when an asteroid impact triggered the extinction of non-avian dinosaurs and other large reptiles, but largely spared small animals such as insects, mammals , lizards and birds. Mammalian life has diversified over

13800-646: The Chinese used the mythological figure of Yu the Great to describe the known earth (of the Chinese). Apart from the appearance of Yu, however, the work was devoid of magic, fantasy, Chinese folklore, or legend. Although the Chinese geographical writing in the time of Herodotus and Strabo were of lesser quality and contained less systematic approach, this would change from the 3rd century onwards, as Chinese methods of documenting geography became more complex than those found in Europe,

13984-583: The Earth is spherical, in the classical world. In the 4th century BC the Greek explorer Pytheas traveled through northeast Europe, and circled the British Isles. He found that the region was considerably more habitable than theory expected, but his discoveries were largely dismissed by his contemporaries because of this. Conquerors also carried out exploration, for example, Caesar's invasions of Britain and Germany , expeditions/invasions sent by Augustus to Arabia Felix and Ethiopia ( Res Gestae 26), and perhaps

14168-589: The Earth. Terra is also the name of the planet in some Romance languages , languages that evolved from Latin , like Italian and Portuguese , while in other Romance languages the word gave rise to names with slightly altered spellings, like the Spanish Tierra and the French Terre . The Latinate form Gæa or Gaea ( English: / ˈ dʒ iː . ə / ) of the Greek poetic name Gaia ( Γαῖα ; Ancient Greek : [ɡâi̯.a] or [ɡâj.ja] )

14352-488: The Earth. The first person to use the word geography was Eratosthenes (276–194 BC). However, there is evidence for recognizable practices of geography, such as cartography , prior to the use of the term. The known world of Ancient Egypt saw the Nile as the center, and the world as based upon "the" river. Various oasis were known to the east and west, and were considered locations of various gods (e.g. Siwa , for Amon). To

14536-533: The Greeks to believe in a division of the world into five regions. At each of the poles was an uncharitably cold region. While extrapolating from the heat of the Sahara it was deduced that the area around the equator was unbearably hot. Between these extreme regions both the northern and southern hemispheres had a temperate belt suitable for human habitation. These theories clashed with the evidence of explorers, however, Hanno

14720-527: The Latin Tellus comes tellurian / t ɛ ˈ l ʊər i ə n / and telluric . The oldest material found in the Solar System is dated to 4.5682 +0.0002 −0.0004 Ga (billion years) ago. By 4.54 ± 0.04 Ga the primordial Earth had formed. The bodies in the Solar System formed and evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into

14904-561: The Middle Ages included: Further details about some of these are given below: In the early 10th century, Abū Zayd al-Balkhī , a Persian originally from Balkh , founded the "Balkhī school" of terrestrial mapping in Baghdad . The geographers of this school also wrote extensively of the peoples, products, and customs of areas in the Muslim world, with little interest in the non-Muslim realms. Suhrāb,

15088-604: The Middle East and Africa, the map includes India, Sri Lanka and China. Cities are demarcated using hundreds of symbols. It measures 1.12 ft (0.34 m) high and 22.15 ft (6.75 m) long. The tools and principles of geography used by the Romans would be closely followed with little practical improvement for the next 700 years. A vast corpus of Indian texts embraced the study of geography. The Vedas and Puranas contain elaborate descriptions of rivers and mountains and treat

15272-460: The Middle East, India, and Central Asia since the traveler Zhang Qian (2nd century BC), later Chinese would provide more concrete and valid information on the topography and geographical aspects of foreign regions. The Tang dynasty (618–907) Chinese diplomat Wang Xuance traveled to Magadha (modern northeastern India) during the 7th century. Afterwards he wrote the book Zhang Tian-zhu Guo Tu (Illustrated Accounts of Central India), which included

15456-426: The Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic activity and outgassing . Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids, protoplanets , and comets . Sufficient water to fill the oceans may have been on Earth since it formed. In this model, atmospheric greenhouse gases kept the oceans from freezing when

15640-462: The Navigator had traveled as far south as Sierra Leone , and Egyptian Pharaoh Necho II of Africa is related by Herodotus and others as having commissioned a successful circumnavigation of Africa by Phoenician sailors. While they were sailing west around the Southern tip of Africa, it was found that the Sun was to their right (the north). This is thought to have been a key trigger in the realization that

15824-670: The Persian Gulf, Arabic writers a century after Jia wrote of the same structures, writers such as al-Mas'udi and al-Muqaddasi . The later Song dynasty ambassador Xu Jing wrote his accounts of voyage and travel throughout Korea in his work of 1124, the Xuan-He Feng Shi Gao Li Tu Jing ( Illustrated Record of an Embassy to Korea in the Xuan-He Reign Period ). The geography of medieval Cambodia (the Khmer Empire )

16008-416: The Solar System . Of the four rocky planets , it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it , taking a year (about 365.25 days) to complete one revolution. Earth rotates around its own axis in slightly less than a day (in about 23 hours and 56 minutes). Earth's axis of rotation is tilted with respect to the perpendicular to its orbital plane around

16192-458: The Solar System's planetary-sized objects, Earth is the object with the highest density . Earth's mass is approximately 5.97 × 10   kg ( 5.970  Yg ). It is composed mostly of iron (32.1% by mass ), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%), with the remaining 1.2% consisting of trace amounts of other elements. Due to gravitational separation ,

16376-663: The Solar System, formed 4.5 billion years ago from gas and dust in the early Solar System . During the first billion years of Earth's history , the ocean formed and then life developed within it. Life spread globally and has been altering Earth's atmosphere and surface, leading to the Great Oxidation Event two billion years ago. Humans emerged 300,000 years ago in Africa and have spread across every continent on Earth. Humans depend on Earth's biosphere and natural resources for their survival, but have increasingly impacted

16560-675: The South lay the Kushitic region, known as far as the 4th cataract. Punt was a region south along the shores of the Red Sea. Various Asiatic peoples were known as Retenu, Kanaan, Que, Harranu, or Khatti ( Hittites ). At various times especially in the Late Bronze Age Egyptians had diplomatic and trade relationships with Babylonia and Elam . The Mediterranean was called "the Great Green" and

16744-403: The Sun when the star reaches its maximum radius, otherwise, with tidal effects, it may enter the Sun's atmosphere and be vaporized. Earth has a rounded shape , through hydrostatic equilibrium , with an average diameter of 12,742 kilometres (7,918 mi), making it the fifth largest planetary sized and largest terrestrial object of the Solar System . Due to Earth's rotation it has

16928-461: The Sun, producing seasons . Earth is orbited by one permanent natural satellite , the Moon , which orbits Earth at 384,400 km (1.28 light seconds) and is roughly a quarter as wide as Earth. The Moon's gravity helps stabilize Earth's axis, causes tides and gradually slows Earth's rotation . Tidal locking has made the Moon always face Earth with the same side. Earth, like most other bodies in

17112-691: The United States is divided into 32 Roman Catholic ecclesiastical provinces . The Lutheran Church–Missouri Synod is organized into 33 geographic districts , which are subdivided into circuits (the Atlantic District (LCMS) , for example). The Church of Jesus Christ of Latter-day Saints uses regions similar to dioceses and parishes, but uses terms like ward and stake . In the field of political geography , regions tend to be based on political units such as sovereign states ; subnational units such as administrative regions, provinces , states (in

17296-679: The United States) , counties , townships , territories , etc.; and multinational groupings, including formally defined units such as the European Union , the Association of Southeast Asian Nations , and NATO , as well as informally defined regions such as the Third World , Western Europe , and the Middle East. The word "region" is taken from the Latin regio (derived from regere , 'to rule'), and

17480-524: The area and suggest a coherent tourism experience to visitors. Countries, states, provinces, and other administrative regions are often carved up into tourism regions to facilitate attracting visitors. Some of the more famous tourism regions based on historical or current administrative regions include Tuscany in Italy and Yucatán in Mexico. Famous examples of regions created by a government or tourism bureau include

17664-425: The atmosphere and due to interaction with ultraviolet solar radiation, formed a protective ozone layer ( O 3 ) in the upper atmosphere. The incorporation of smaller cells within larger ones resulted in the development of complex cells called eukaryotes . True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful ultraviolet radiation by

17848-426: The atmosphere, particularly carbon dioxide (CO 2 ), creates the conditions for both liquid surface water and water vapor to persist via the capturing of energy from the Sun's light . This process maintains the current average surface temperature of 14.76 °C (58.57 °F), at which water is liquid under normal atmospheric pressure. Differences in the amount of captured energy between geographic regions (as with

18032-575: The basis of the modern administrative divisions of these countries, but still define and delimit local regional identity and sense of belonging. Examples are: Functional regions are usually understood to be the areas organised by the horizontal functional relations (flows, interactions) that are maximised within a region and minimised across its borders so that the principles of internal cohesiveness and external separation regarding spatial interactions are met (see, for instance, Farmer and Fotheringham, 2011; Klapka, Halas, 2016; Smart, 1974). A functional region

18216-611: The book's descriptions pertaining to areas of the Yellow River , the lower valleys of the Yangtze and the plain between them as well as the Shandong peninsula and to the west the most northern parts of the Wei and Han Rivers along with the southern parts of modern-day Shanxi province. In this ancient geographical treatise, which would greatly influence later Chinese geographers and cartographers,

18400-450: The center, the temperature may be up to 6,000 °C (10,830 °F), and the pressure could reach 360  GPa (52 million  psi ). Because much of the heat is provided by radioactive decay, scientists postulate that early in Earth's history, before isotopes with short half-lives were depleted, Earth's heat production was much higher. At approximately 3  Gyr , twice the present-day heat would have been produced, increasing

18584-431: The concept of regions is important and widely used among the many branches of geography, each of which can describe areas in regional terms. For example, ecoregion is a term used in environmental geography , cultural region in cultural geography , bioregion in biogeography , and so on. The field of geography that studies regions themselves is called regional geography . Regions are an area or division, especially part of

18768-499: The contact between the "Old" and "New World"s producing the Columbian Exchange : a wide transfer of plants, animals, foods, human populations (including slaves ), communicable diseases and culture between the continents. These colonialist endeavours in 16th and 17th centuries revived a desire for both "accurate" geographic detail, and more solid theoretical foundations. The Geographia Generalis by Bernhardus Varenius , which

18952-454: The continental crust , particularly during the early stages of Earth's history. New continental crust forms as a result of plate tectonics , a process ultimately driven by the continuous loss of heat from Earth's interior. Over the period of hundreds of millions of years, tectonic forces have caused areas of continental crust to group together to form supercontinents that have subsequently broken apart. At approximately 750 Ma , one of

19136-616: The continental surfaces are covered by sedimentary rocks, although they form about 5% of the mass of the crust. Earth's surface topography comprises both the topography of the ocean surface , and the shape of Earth's land surface. The submarine terrain of the ocean floor has an average bathymetric depth of 4 km, and is as varied as the terrain above sea level. Earth's surface is continually being shaped by internal plate tectonic processes including earthquakes and volcanism ; by weathering and erosion driven by ice, water, wind and temperature; and by biological processes including

19320-419: The core are chaotic; the magnetic poles drift and periodically change alignment. This causes secular variation of the main field and field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago. The extent of Earth's magnetic field in space defines the magnetosphere . Ions and electrons of the solar wind are deflected by

19504-527: The core is primarily composed of the denser elements: iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements. The most common rock constituents of the crust are oxides . Over 99% of the crust is composed of various oxides of eleven elements, principally oxides containing silicon (the silicate minerals ), aluminium, iron, calcium, magnesium, potassium, or sodium. The major heat-producing isotopes within Earth are potassium-40 , uranium-238 , and thorium-232 . At

19688-463: The core, through the mantle, and up to Earth's surface, where it is, approximately, a dipole . The poles of the dipole are located close to Earth's geographic poles. At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05 × 10 T , with a magnetic dipole moment of 7.79 × 10 Am at epoch 2000, decreasing nearly 6% per century (although it still remains stronger than its long time average). The convection movements in

19872-623: The creation of perfectly straight stretches, some as long as 35 miles (56 km), would have been impossible. During the Greco-Roman era, those who performed geographical work could be divided into four categories: Around AD 400 a scroll map called the Peutinger Table was made of the known world, featuring the Roman road network. Besides the Roman Empire which at that time spanned from Britain to

20056-524: The days shorter. Above the Arctic Circle and below the Antarctic Circle there is no daylight at all for part of the year, causing a polar night , and this night extends for several months at the poles themselves. These same latitudes also experience a midnight sun , where the sun remains visible all day. By astronomical convention, the four seasons can be determined by the solstices—the points in

20240-462: The descriptions of areas such as India are mostly imaginary. Regardless, Herodotus made important observations about geography. He is the first to have noted the process by which large rivers, such as the Nile, build up deltas , and is also the first recorded as observing that winds tend to blow from colder regions to warmer ones. Pythagoras was perhaps the first to propose a spherical world, arguing that

20424-441: The destructive solar winds and cosmic radiation . Earth has a dynamic atmosphere , which sustains Earth's surface conditions and protects it from most meteoroids and UV-light at entry . It has a composition of primarily nitrogen and oxygen . Water vapor is widely present in the atmosphere, forming clouds that cover most of the planet. The water vapor acts as a greenhouse gas and, together with other greenhouse gases in

20608-522: The discourse. The European global conquests started in the early 15th century with the first Portuguese expeditions to Africa and India, as well as the conquest of America by Spain in 1492 and continued with a series of European naval expeditions across the Atlantic and later the Pacific and Russian expeditions to Siberia until the 18th century. European overseas expansion led to the rise of colonial empires , with

20792-568: The earlier geographical works of India and the advances made by medieval Muslim geographers, particularly the work of Alberuni . In China, the earliest known geographical Chinese writing dates back to the 5th century BC, during the beginning of the Warring States period (481 BC – 221 BC). This work was the Yu Gong ('Tribute of Yu') chapter of the Shu Jing or Book of Documents , which describes

20976-605: The earliest known supercontinents, Rodinia , began to break apart. The continents later recombined to form Pannotia at 600–540 Ma , then finally Pangaea , which also began to break apart at 180 Ma . The most recent pattern of ice ages began about 40 Ma , and then intensified during the Pleistocene about 3 Ma . High- and middle-latitude regions have since undergone repeated cycles of glaciation and thaw, repeating about every 21,000, 41,000 and 100,000 years. The Last Glacial Period , colloquially called

21160-434: The early modern period and led to Siberian regionalism . A tourism region is a geographical region that has been designated by a governmental organization or tourism bureau as having common cultural or environmental characteristics. These regions are often named after a geographical, former, or current administrative region or may have a name created for tourism purposes. The names often evoke certain positive qualities of

21344-479: The editorship of Prince Liu An in 139 BC during the Han dynasty (202 BC – 202 AD). The chapter gave general descriptions of topography in a systematic fashion, given visual aids by the use of maps (di tu) due to the efforts of Liu An and his associate Zuo Wu. In Chang Chu's Hua Yang Guo Chi ( Historical Geography of Sichuan ) of 347, not only rivers, trade routes, and various tribes were described, but it also wrote of

21528-458: The encircling ocean. The descriptions of five of them have survived. In contrast to the Imago Mundi , an earlier Babylonian world map dating back to the 9th century BC depicted Babylon as being further north from the center of the world, though it is not certain what that center was supposed to represent. The ancient Greeks viewed Homer as the founder of geography. His works the Iliad and

21712-544: The equally large area of land under permafrost ) or deserts (33%). The pedosphere is the outermost layer of Earth's land surface and is composed of soil and subject to soil formation processes. Soil is crucial for land to be arable. Earth's total arable land is 10.7% of the land surface, with 1.3% being permanent cropland. Earth has an estimated 16.7 million km (6.4 million sq mi) of cropland and 33.5 million km (12.9 million sq mi) of pastureland. The land surface and

21896-405: The first time knowledge of the far east began to be known. Ptolemy's Geographia opens with a theoretical discussion about the nature and techniques of geographical inquiry, and then moves to detailed descriptions of much the known world. Ptolemy lists a huge number of cities, tribes, and sites and places them in the world. It is uncertain what Ptolemy's names correspond to in the modern world, and

22080-562: The general sense of being bounded spatial units. Examples include electoral districts such as Washington's 6th congressional district and Tennessee's 1st congressional district ; school districts such as Granite School District and Los Angeles Unified School District ; economic districts such as the Reedy Creek Improvement District ; metropolitan areas such as the Seattle metropolitan area , and metropolitan districts such as

22264-470: The geography of Europe and Asia, based in their governance and ruling of much of this area and used this information for the undertaking of large military expeditions. The evidence for this is found in historical resources such as The Secret History of Mongols and other Persian chronicles written in 13th and 14th centuries. For example, during the rule of the Great Yuan Dynasty a world map was created and

22448-463: The great learning center the House of Wisdom at Baghdad , today's Iraq . Early caliphs did not follow orthodoxy and so they encouraged scholarship. Under their rule, native non-Arabs served as mawali or dhimmi , and most geographers in this period were Syrian ( Byzantine ) or Persian, i.e. of either Zoroastrian or Christian background. Persians who wrote on geography or created maps during

22632-465: The greatest Ancient Greek explorer of all, Alexander the Great , who deliberately set out to learn more about the east through his military expeditions and so took a large number of geographers and writers with his army who recorded their observations as they moved east. The ancient Greeks divided the world into three continents, Europe, Asia, and Libya (Africa). The Hellespont formed the border between Europe and Asia. The border between Asia and Libya

22816-638: The growth and decomposition of biomass into soil . Earth's mechanically rigid outer layer of Earth's crust and upper mantle , the lithosphere , is divided into tectonic plates . These plates are rigid segments that move relative to each other at one of three boundaries types: at convergent boundaries , two plates come together; at divergent boundaries , two plates are pulled apart; and at transform boundaries , two plates slide past one another laterally. Along these plate boundaries, earthquakes, volcanic activity , mountain-building , and oceanic trench formation can occur. The tectonic plates ride on top of

23000-404: The heat in Earth is lost through plate tectonics, by mantle upwelling associated with mid-ocean ridges . The final major mode of heat loss is through conduction through the lithosphere, the majority of which occurs under the oceans. The gravity of Earth is the acceleration that is imparted to objects due to the distribution of mass within Earth. Near Earth's surface, gravitational acceleration

23184-688: The heights of mountains and depths of valleys , recorded in The Chronology of the Ancient Nations . He discussed human geography and the planetary habitability of the Earth , suggesting that roughly a quarter of the Earth's surface is habitable by humans . By the early 12th century the Normans had overthrown the Arabs in Sicily . Palermo had become a crossroads for travelers and traders from many nations and

23368-567: The information inherited from the classical geographers, he created one of the most accurate maps of the world to date, the Tabula Rogeriana (1154). The map, written in Arabic, shows the Eurasian continent in its entirety and the northern part of Africa. An adherent of environmental determinism was the medieval Afro-Arab writer al-Jahiz (776–869), who explained how the environment can determine

23552-478: The interaction between humans and nature, with Marxist thought critiquing nature as a commodity within Capitalism, European thought seeing nature as either a romanticised or objective concept differing to human society, and Native American discourse, which saw nature and humans as within one category. The implied hierarchy of knowledge that perpetuated throughout these institutions has only been recently challenged, with

23736-406: The land surface is taken by the four continental landmasses , which are (in descending order): Africa-Eurasia , America (landmass) , Antarctica , and Australia (landmass) . These landmasses are further broken down and grouped into the continents . The terrain of the land surface varies greatly and consists of mountains, deserts , plains , plateaus , and other landforms . The elevation of

23920-508: The land surface varies from a low point of −418 m (−1,371 ft) at the Dead Sea , to a maximum altitude of 8,848 m (29,029 ft) at the top of Mount Everest . The mean height of land above sea level is about 797 m (2,615 ft). Land can be covered by surface water , snow, ice, artificial structures or vegetation. Most of Earth's land hosts vegetation, but considerable amounts of land are ice sheets (10%, not including

24104-560: The land surrounded by a sea. Though he described the Phoenicians as having circumnavigated Africa in the 6th century BC, through much of later European history the Indian Ocean was thought to be an inland sea, the southern part of Africa wrapping around in the south to connect with the eastern part of Asia. This was not completely abandoned by Western cartographers until the circumnavigation of Africa by Vasco da Gama . Some, though, hold that

24288-399: The largest of water regions known as oceans . There are also significant regions that do not belong to either classification, such as archipelago regions that are littoral regions, or earthquake regions that are defined in geology . Continental regions are usually based on broad experiences in human history and attempt to reduce very large areas to more manageable regionalization for

24472-399: The lithosphere, which is divided into independently moving tectonic plates. Beneath the lithosphere is the asthenosphere , a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 km (250 and 410 mi) below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath

24656-452: The locations of small gorges, or mineral beds such as mica schists. Xu's work was largely systematic, providing accurate details of measurement, and his work (translated later by Ding Wenjiang) read more like a 20th-century field surveyor than an early 17th-century scholar. The Chinese were also concerned with documenting geographical information of foreign regions far outside of China. Although Chinese had been writing of civilizations of

24840-410: The loss of oxygen in the atmosphere, making current animal life impossible. Due to the increased luminosity, Earth's mean temperature may reach 100 °C (212 °F) in 1.5 billion years, and all ocean water will evaporate and be lost to space, which may trigger a runaway greenhouse effect , within an estimated 1.6 to 3 billion years. Even if the Sun were stable, a fraction of the water in

25024-456: The lowercase when it is preceded by "the", such as "the atmosphere of the earth". It almost always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The name Terra / ˈ t ɛr ə / occasionally is used in scientific writing and especially in science fiction to distinguish humanity's inhabited planet from others, while in poetry Tellus / ˈ t ɛ l ə s / has been used to denote personification of

25208-497: The magnetosphere. During magnetic storms and substorms , charged particles can be deflected from the outer magnetosphere and especially the magnetotail, directed along field lines into Earth's ionosphere , where atmospheric atoms can be excited and ionized, causing an aurora . Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time ( 86,400.0025 SI seconds ). Because Earth's solar day

25392-409: The magnetosphere; solar wind pressure compresses the day-side of the magnetosphere, to about 10 Earth radii, and extends the night-side magnetosphere into a long tail. Because the velocity of the solar wind is greater than the speed at which waves propagate through the solar wind, a supersonic bow shock precedes the day-side magnetosphere within the solar wind. Charged particles are contained within

25576-478: The magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates. The ring current is defined by medium-energy particles that drift relative to the geomagnetic field, but with paths that are still dominated by the magnetic field, and the Van Allen radiation belts are formed by high-energy particles whose motion is essentially random, but contained in

25760-432: The major focus of human geography is not the physical landscape of the Earth (see physical geography ), it is hardly possible to discuss human geography without referring to the physical landscape on which human activities are being played out, and environmental geography is emerging as a link between the two. Regions of human geography can be divided into many broad categories: The field of historical geography involves

25944-417: The mantle, an extremely low viscosity liquid outer core lies above a solid inner core . Earth's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year, although both somewhat higher and much lower rates have also been proposed. The radius of the inner core is about one-fifth of that of Earth. The density increases with depth. Among

26128-600: The mantle. Due to this recycling, most of the ocean floor is less than 100 Ma old. The oldest oceanic crust is located in the Western Pacific and is estimated to be 200 Ma old. By comparison, the oldest dated continental crust is 4,030 Ma , although zircons have been found preserved as clasts within Eoarchean sedimentary rocks that give ages up to 4,400 Ma , indicating that at least some continental crust existed at that time. The seven major plates are

26312-548: The modern oceans will descend to the mantle , due to reduced steam venting from mid-ocean ridges. The Sun will evolve to become a red giant in about 5 billion years . Models predict that the Sun will expand to roughly 1  AU (150 million km; 93 million mi), about 250 times its present radius. Earth's fate is less clear. As a red giant, the Sun will lose roughly 30% of its mass, so, without tidal effects, Earth will move to an orbit 1.7 AU (250 million km; 160 million mi) from

26496-636: The monasteries and libraries, they discovered the Greek classics which included great works of geography by Egyptian Ptolemy's Almagest and Geography , along with the geographical wisdom of the Chinese and the great accomplishments of the Roman Empire . The Arabs , who spoke only Arabic , employed Christians and Jews to translate these and many other manuscripts into Arabic. The primary geographical scholarship of this era occurred in Persia , today's Iran , in

26680-635: The more commonly used terms being "Abya Yala", meaning "land of vital blood". These indigenous geographical discourses were largely ignored or appropriated by the European colonialists to make way for European thought. The Eurocentric map was patterned after a modification of Ptolemy's second projection but expanded to include the Americas. The Waldseemuller Map has been called "America's birth certificate" Waldseemüller also created printed maps called globe gores, that could be cut out and glued to spheres resulting in

26864-399: The mother of Thor . Historically, "Earth" has been written in lowercase. Beginning with the use of Early Middle English , its definite sense as "the globe" was expressed as "the earth". By the era of Early Modern English , capitalization of nouns began to prevail , and the earth was also written the Earth , particularly when referenced along with other heavenly bodies. More recently,

27048-424: The name is sometimes simply given as Earth , by analogy with the names of the other planets , though "earth" and forms with "the earth" remain common. House styles now vary: Oxford spelling recognizes the lowercase form as the more common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name, such as a description of the "Earth's atmosphere", but employs

27232-600: The name of a type of subnational administrative unit: The Canadian province of Québec also uses the "administrative region" ( région administrative ). Scotland had local government regions from 1975 to 1996. In Spain the official name of the autonomous community of Murcia is Región de Murcia . Also, some single-province autonomous communities such as Madrid use the term región interchangeably with comunidad autónoma . Two län (counties) in Sweden are officially called 'regions': Skåne and Västra Götaland , and there

27416-524: The new title of Shui Jing Zhu ( The Waterways Classic Commented ). In later periods of the Song dynasty (960–1279) and Ming dynasty (1368–1644), there were much more systematic and professional approaches to geographic literature. The Song dynasty poet, scholar, and government official Fan Chengda (1126–1193) wrote the geographical treatise known as the Gui Hai Yu Heng Chi . It focused primarily on

27600-425: The newly forming Sun had only 70% of its current luminosity . By 3.5 Ga , Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind . As the molten outer layer of Earth cooled it formed the first solid crust , which is thought to have been mafic in composition. The first continental crust , which was more felsic in composition, formed by

27784-586: The ocean may have covered Earth completely. The world ocean is commonly divided into the Pacific Ocean, Atlantic Ocean, Indian Ocean, Antarctic or Southern Ocean , and Arctic Ocean, from largest to smallest. The ocean covers Earth's oceanic crust , with the shelf seas covering the shelves of the continental crust to a lesser extent. The oceanic crust forms large oceanic basins with features like abyssal plains , seamounts , submarine volcanoes , oceanic trenches , submarine canyons , oceanic plateaus , and

27968-648: The oceanic plates, with the Cocos Plate advancing at a rate of 75 mm/a (3.0 in/year) and the Pacific Plate moving 52–69 mm/a (2.0–2.7 in/year). At the other extreme, the slowest-moving plate is the South American Plate, progressing at a typical rate of 10.6 mm/a (0.42 in/year). Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical ( rheological ) properties. The outer layer

28152-581: The orbit of maximum axial tilt toward or away from the Sun—and the equinoxes , when Earth's rotational axis is aligned with its orbital axis. In the Northern Hemisphere, winter solstice currently occurs around 21 December; summer solstice is near 21 June, spring equinox is around 20 March and autumnal equinox is about 22 or 23 September. In the Southern Hemisphere, the situation is reversed, with

28336-421: The origin of the Earth. They theorized that the Earth was formed by the solidification of gaseous matter and that the Earth's crust is composed of hard rocks (sila), clay (bhumih) and sand (asma). Theories were also propounded to explain earthquakes (bhukamp) and it was assumed that earth, air and water combined to cause earthquakes. The Arthashastra , a compendium by Kautilya (also known as Chanakya ) contains

28520-625: The ozone layer, life colonized Earth's surface. Among the earliest fossil evidence for life is microbial mat fossils found in 3.48 billion-year-old sandstone in Western Australia , biogenic graphite found in 3.7 billion-year-old metasedimentary rocks in Western Greenland , and remains of biotic material found in 4.1 billion-year-old rocks in Western Australia. The earliest direct evidence of life on Earth

28704-469: The partial melting of this mafic crust. The presence of grains of the mineral zircon of Hadean age in Eoarchean sedimentary rocks suggests that at least some felsic crust existed as early as 4.4 Ga , only 140  Ma after Earth's formation. There are two main models of how this initial small volume of continental crust evolved to reach its current abundance: (1) a relatively steady growth up to

28888-501: The past 66 Mys , and several million years ago, an African ape species gained the ability to stand upright. This facilitated tool use and encouraged communication that provided the nutrition and stimulation needed for a larger brain, which led to the evolution of humans . The development of agriculture , and then civilization , led to humans having an influence on Earth and the nature and quantity of other life forms that continues to this day. Earth's expected long-term future

29072-489: The physical characteristics of the inhabitants of a certain community. He used his early theory of evolution to explain the origins of different human skin colors , particularly black skin, which he believed to be the result of the environment. He cited a stony region of black basalt in the northern Najd as evidence for his theory. During the Early Middle Ages , geographical knowledge in Europe regressed (though it

29256-478: The planet's environment . Humanity's current impact on Earth's climate and biosphere is unsustainable , threatening the livelihood of humans and many other forms of life, and causing widespread extinctions . The Modern English word Earth developed, via Middle English , from an Old English noun most often spelled eorðe . It has cognates in every Germanic language , and their ancestral root has been reconstructed as * erþō . In its earliest attestation,

29440-421: The polar Northern and Southern hemispheres; or by longitude into the continental Eastern and Western hemispheres. Most of Earth's surface is ocean water: 70.8% or 361 million km (139 million sq mi). This vast pool of salty water is often called the world ocean , and makes Earth with its dynamic hydrosphere a water world or ocean world . Indeed, in Earth's early history

29624-441: The present day, which is supported by the radiometric dating of continental crust globally and (2) an initial rapid growth in the volume of continental crust during the Archean , forming the bulk of the continental crust that now exists, which is supported by isotopic evidence from hafnium in zircons and neodymium in sedimentary rocks. The two models and the data that support them can be reconciled by large-scale recycling of

29808-417: The purpose of the study. As such they are conceptual constructs, usually lacking distinct boundaries. The oceanic division into maritime regions is used in conjunction with the relationship to the central area of the continent, using directions of the compass . Some continental regions are defined by the major continental feature of their identity, such as the Amazon basin , or the Sahara , which both occupy

29992-493: The rates of mantle convection and plate tectonics, and allowing the production of uncommon igneous rocks such as komatiites that are rarely formed today. The mean heat loss from Earth is 87 mW m , for a global heat loss of 4.42 × 10  W . A portion of the core's thermal energy is transported toward the crust by mantle plumes , a form of convection consisting of upwellings of higher-temperature rock. These plumes can produce hotspots and flood basalts . More of

30176-442: The regions and subregions are described by the discipline of ethnography . Global regions are distinguishable from space, and are therefore clearly distinguished by the two basic terrestrial environments, land and water . However, they have been generally recognized as such much earlier by terrestrial cartography because of their impact on human geography. They are divided into the largest of land regions, known as continents and

30360-541: The relationship between physical and human elements. According to religious scholar Diana Eck , a notable feature of geography in India is its interweaving with Hindu mythology, No matter where one goes in India, one will find a landscape in which mountains, rivers, forests, and villages are elaborately linked to the stories and gods of Indian culture. Every place in this vast country has its story; and conversely, every story of Hindu myth and legend has its place. The geographers of ancient India put forward theories regarding

30544-459: The shape of an ellipsoid , bulging at its Equator ; its diameter is 43 kilometres (27 mi) longer there than at its poles . Earth's shape also has local topographic variations; the largest local variations, like the Mariana Trench (10,925 metres or 35,843 feet below local sea level), shortens Earth's average radius by 0.17% and Mount Everest (8,848 metres or 29,029 feet above local sea level) lengthens it by 0.14%. Since Earth's surface

30728-442: The sphere was the most perfect form. This idea was embraced by Plato , and Aristotle presented empirical evidence to verify this. He noted that the Earth's shadow during a lunar eclipse is curved from any angle (near the horizon or high in the sky), and also that stars increase in height as one moves north. Eudoxus of Cnidus used the idea of a sphere to explain how the sun created differing climatic zones based on latitude. This led

30912-425: The study of human history as it relates to places and regions , or the study of how places and regions have changed over time. D. W. Meinig , a historical geographer of America, describes many historical regions in his book The Shaping of America: A Geographical Perspective on 500 Years of History . For example, in identifying European "source regions" in early American colonization efforts, he defines and describes

31096-495: The summer and winter solstices exchanged and the spring and autumnal equinox dates swapped. History of geography The History of geography includes many histories of geography which have differed over time and between different cultural and political groups. In more recent developments, geography has become a distinct academic discipline. 'Geography' derives from the Greek γεωγραφία – geographia , literally "Earth-writing", that is, description or writing about

31280-568: The topics of these chapters. Varāhamihira 's Brihat-Samhita gave a thorough treatment of planetary movements, rainfall, clouds and the formation of water. The mathematician-astronomer Aryabhatiya gave a precise estimate of the Earth's circumference in his treatise Āryabhaṭīya . Aryabhata accurately calculated the Earth's circumference as 24,835 miles, which was only 0.2% smaller than the actual value of 24,902 miles. The Mughal chronicles Tuzuk-i-Jehangiri, Ain-i-Akbari and Dastur-ul-aml contain detailed geographical narratives. These were based on

31464-410: The traditional nine provinces of ancient China, their kinds of soil, their characteristic products and economic goods, their tributary goods, their trades and vocations, their state revenues and agricultural systems, and the various rivers and lakes listed and placed accordingly. The nine provinces at the time of this geographical work were relatively small in size compared to those of modern China with

31648-406: The word eorðe was used to translate the many senses of Latin terra and Greek γῆ gē : the ground, its soil , dry land, the human world, the surface of the world (including the sea), and the globe itself. As with Roman Terra /Tellūs and Greek Gaia , Earth may have been a personified goddess in Germanic paganism : late Norse mythology included Jörð ("Earth"), a giantess often given as

31832-484: The works of almost all earlier geographers have been lost, many of them are partially known through quotations found in Strabo (64/63 BC – ca. AD 24). Strabo's seventeen volume work of geography is almost completely extant, and is one of the most important sources of information on classical geography. Strabo accepted the narrow band of habitation theory, and rejected the accounts of Hanno and Pytheas as fables. None of Strabo's maps survive, but his detailed descriptions give

32016-400: The world as a grand machine from the Divine. Scientific voyages and travels constructed geopolitical power from geographical knowledge, partly sponsored by Royal Society . The discourse of geographical history gave way to many new thoughts and theories, but the hegemony of the European male academia led to the exclusion of non-western theories, observations and knowledges. One such example is

32200-428: The year. This causes the seasonal change in climate, with summer in the Northern Hemisphere occurring when the Tropic of Cancer is facing the Sun, and in the Southern Hemisphere when the Tropic of Capricorn faces the Sun. In each instance, winter occurs simultaneously in the opposite hemisphere. During the summer, the day lasts longer, and the Sun climbs higher in the sky. In winter, the climate becomes cooler and

32384-442: Was "the science of imperialism par excellence." Imperialism is a crucial concept for the Europeans, as the institution become involved in geographical exploration and colonial project. Authority was questioned, and utility gained its importance. In the era of Enlightenment, geography generated knowledge and made it intellectually and practically possible as a university discipline. The natural theology required geography to investigate

32568-445: Was believed to be part of a world encircling ocean. Europe was unknown although may have become part of the Egyptian world view in Phoenician times. To the west of Asia lay the realms of Keftiu , possibly Crete , and Mycenae (thought to be part of a chain of islands, that joined Cyprus , Crete, Sicily and later perhaps Sardinia , Corsica and the Balearics to Africa). The oldest known world maps date back to ancient Babylon from

32752-440: Was documented in the book Zhen-La Feng Tu Ji of 1297, written by Zhou Daguan . After the fall of the western Roman Empire, the Eastern Roman Empire , ruled from Constantinople and known as the Byzantine Empire , continued to thrive and produced several noteworthy geographers. Stephanus of Byzantium (6th century) was a grammarian at Constantinople and authored the important geographical dictionary Ethnica . This work

32936-434: Was generally considered to be the Nile river, but some geographers, such as Herodotus objected to this. Herodotus argued that there was no difference between the people on the east and west sides of the Nile, and that the Red Sea was a better border. The relatively narrow habitable band was considered to run from the Atlantic Ocean in the west to an unknown sea somewhere east of India in the east. The southern portion of Africa

33120-433: Was in the vast region east of Asia and to the west of Europe. Crates of Mallus proposed that there were in fact four inhabitable land masses, two in each hemisphere. In Rome a large globe was created depicting this world. Posidonius set out to get a measurement, but his number actually was considerably smaller than the real one, yet it became accepted that the eastern part of Asia was not a huge distance from Europe. While

33304-400: Was known of the world. A similar work, and one that mostly survives today, is Herodotus ' Histories . While primarily a work of history, the book contains a wealth of geographic descriptions covering much of the known world. Egypt, Scythia, Persia, and Asia Minor are all described, including a mention of India. The description of Africa as a whole are contentious, with Herodotus describing

33488-424: Was the first to describe a polar equi- azimuthal equidistant projection of the celestial sphere . He was also regarded as the most skilled when it came to mapping cities and measuring the distances between them, which he did for many cities in the Middle East and western Indian subcontinent . He combined astronomical readings and mathematical equations to record degrees of latitude and longitude and to measure

33672-423: Was unknown, as was the northern portion of Europe and Asia, so it was believed that they were circled by a sea. These areas were generally considered uninhabitable. The size of the Earth was an important question to the Ancient Greeks. Eratosthenes calculated the Earth's circumference with great precision. Since the distance from the Atlantic to India was roughly known, this raised the important question of what

33856-453: Was used in Newton 's teaching of geography at Cambridge , and Gerardus Mercator 's world map are prime examples of the new breed of scientific geography. The Waldseemüller map Universalis Cosmographia , created by German cartographer Martin Waldseemüller in April 1507, is the first map of the Americas in which the name "America" is mentioned. Before this, the Native Americans referred to their land depending on their location, with one of

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