158-404: In geography and seamanship , windward ( / ˈ w ɪ n d w ər d , ˈ w ɪ n ər d / ) and leeward ( / ˈ l iː w ər d , ˈ lj uː ər d / ) are directions relative to the wind . Windward is upwind from the point of reference, i.e., towards the direction from which the wind is coming; leeward is downwind from the point of reference, i.e., along the direction towards which
316-540: 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
474-474: 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 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
632-492: 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
790-402: A consequence of accessibility ." Geography is a branch of inquiry that focuses on spatial information on Earth. It is an extremely broad topic and can be broken down multiple ways. There have been several approaches to doing this spanning at least several centuries, including "four traditions of geography" and into distinct branches. The Four traditions of geography are often used to divide
948-548: 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
1106-526: A focus on space, place, time, and scale. Today, geography is an extremely broad discipline with multiple approaches and modalities. There have been multiple attempts to organize the discipline, including the four traditions of geography, and into branches. Techniques employed can generally be broken down into quantitative and qualitative approaches, with many studies taking mixed-methods approaches. Common techniques include cartography , remote sensing , interviews , and surveying . Geography
1264-420: 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
1422-418: A geographic information system). Remote sensing aids in land use, land cover (LULC) mapping, by helping to determine both what is naturally occurring on a piece of land and what human activities are taking place on it. Geostatistics deal with quantitative data analysis, specifically the application of a statistical methodology to the exploration of geographic phenomena. Geostatistics is used extensively in
1580-421: 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
1738-610: A high level of information for Ptolemy to construct detailed atlases . He extended the work of Hipparchus , using a grid system on his maps and adopting a length of 56.5 miles for a degree. From the 3rd century onwards, Chinese methods of geographical study and writing of geographical literature became much more comprehensive than what was found in Europe at the time (until the 13th century). Chinese geographers such as Liu An , Pei Xiu , Jia Dan , Shen Kuo , Fan Chengda , Zhou Daguan , and Xu Xiake wrote important treatises, yet by
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#17327654042041896-493: A history, they also exist in space and have a geography. For something to exist in the realm of geography, it must be able to be described spatially. Thus, space is the most fundamental concept at the foundation of geography. The concept is so basic, that geographers often have difficulty defining exactly what it is. Absolute space is the exact site, or spatial coordinates, of objects, persons, places, or phenomena under investigation. We exist in space. Absolute space leads to
2054-425: A liquid outer core that generates a magnetosphere capable of deflecting most of 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
2212-565: A product with greater information than a two-dimensional image of places, names, and topography. This approach offers more inclusive strategies than more traditional cartographic approaches for connecting the complex layers that makeup places. Ethnographical research techniques are used by human geographers. In cultural geography , there is a tradition of employing qualitative research techniques, also used in anthropology and sociology. Participant observation and in-depth interviews provide human geographers with qualitative data. Geopoetics
2370-479: A single person from a single location. The European Age of Discovery during the 16th and the 17th centuries, where many new lands were discovered and accounts by European explorers such as Christopher Columbus , Marco Polo , and James Cook revived a desire for both accurate geographic detail and more solid theoretical foundations in Europe. In 1650, the first edition of the Geographia Generalis
2528-434: A structured or semi-structured approach during interviews involving specific questions or discussion points when utilized for research purposes. These questions are designed to extract focused information about the research topic while being flexible enough to allow participants to express their experiences and viewpoints, such as through open-ended questions. The concept of geography is present in all cultures, and therefore
2686-439: A system. The amount of time an individual, or group of people, spends in a place will often shape their attachment and perspective to that place. Time constrains the possible paths that can be taken through space, given a starting point, possible routes, and rate of travel. Visualizing time over space is challenging in terms of cartography, and includes Space-Prism, advanced 3D geovisualizations, and animated maps . Scale in
2844-417: A variety of fields, including hydrology , geology, petroleum exploration, weather analysis, urban planning , logistics, and epidemiology . The mathematical basis for geostatistics derives from cluster analysis , linear discriminant analysis and non-parametric statistical tests , and a variety of other subjects. Applications of geostatistics rely heavily on geographic information systems , particularly for
3002-514: Is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in 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
3160-456: 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
3318-610: Is a systematic study of the Earth (other celestial bodies are specified, such as "geography of Mars", or given another name, such as areography in the case of Mars), its features, and phenomena that take place on it. For something to fall into the domain of geography, it generally needs some sort of spatial component that can be placed on a map , such as coordinates , place names, or addresses . This has led to geography being associated with cartography and place names. Although many geographers are trained in toponymy and cartology, this
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#17327654042043476-750: Is an interdisciplinary approach that combines geography and poetry to explore the interconnectedness between humans, space, place, and the environment. Geopoetics is employed as a mixed methods tool to explain the implications of geographic research. It is often employed to address and communicate the implications of complex topics, such as the anthropocene . Geographers employ interviews to gather data and acquire valuable understandings from individuals or groups regarding their encounters, outlooks, and opinions concerning spatial phenomena. Interviews can be carried out through various mediums, including face-to-face interactions, phone conversations, online platforms, or written exchanges. Geographers typically adopt
3634-436: Is an ongoing source of debate in geography and is unlikely to be resolved anytime soon. Several laws have been proposed, and Tobler's first law of geography is the most generally accepted in geography. Some have argued that geographic laws do not need to be numbered. The existence of a first invites a second, and many have proposed themselves as that. It has also been proposed that Tobler's first law of geography should be moved to
3792-483: 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
3950-414: Is concerned with the study of processes and patterns in the natural environment like the atmosphere , hydrosphere , biosphere , and geosphere . Technical geography is interested in studying and applying techniques and methods to store, process, analyze, visualize, and use spatial data. It is the newest of the branches, the most controversial, and often other terms are used in the literature to describe
4108-529: 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
4266-479: Is credited to Hipparchus . He employed a sexagesimal system that was derived from Babylonian mathematics . The meridians were subdivided into 360°, with each degree further subdivided into 60 ( minutes ). To measure the longitude at different locations on Earth, he suggested using eclipses to determine the relative difference in time. The extensive mapping by the Romans as they explored new lands would later provide
4424-457: 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
4582-516: 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
4740-469: Is impacted by all other locations on Earth. In one of Yi-Fu Tuan 's papers, he explains that in his view, geography is the study of Earth as a home for humanity, and thus place and the complex meaning behind the term is central to the discipline of geography. Time is usually thought to be within the domain of history , however, it is of significant concern in the discipline of geography. In physics, space and time are not separated, and are combined into
4898-482: Is land, most of which is located in the form of continental landmasses within Earth's land hemisphere . Most of Earth's land 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
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5056-426: Is liquid under normal atmospheric pressure. Differences in the amount of captured energy between geographic regions (as with 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
5214-417: Is not certain what that center was supposed to represent. The ideas of Anaximander (c. 610–545 BC): considered by later Greek writers to be the true founder of geography, come to us through fragments quoted by his successors. Anaximander is credited with the invention of the gnomon , the simple, yet efficient Greek instrument that allowed the early measurement of latitude . Thales is also credited with
5372-438: Is not their main preoccupation. Geographers study the Earth's spatial and temporal distribution of phenomena, processes, and features as well as the interaction of humans and their environment . Because space and place affect a variety of topics, such as economics, health, climate , plants, and animals, geography is highly interdisciplinary. The interdisciplinary nature of the geographical approach depends on an attentiveness to
5530-513: 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
5688-535: Is one of the broadest, is consistent with the naming convention of the other two branches, has been in use since the 1700s, and has been used by the UNESCO Encyclopedia of Life Support Systems to divide geography into themes. As academic fields increasingly specialize in their nature, technical geography has emerged as a branch of geography specializing in geographic methods and thought. The emergence of technical geography has brought new relevance to
5846-622: 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
6004-454: Is related to everything else, but near things are more related than distant things." As spatial interrelationships are key to this synoptic science, maps are a key tool. Classical cartography has been joined by a more modern approach to geographical analysis, computer-based geographic information systems (GIS). In their study, geographers use four interrelated approaches: Quantitative methods in geography became particularly influential in
6162-430: Is spherical in shape, with the credit going either to Parmenides or Pythagoras . Anaxagoras was able to demonstrate that the profile of the Earth was circular by explaining eclipses . However, he still believed that the Earth was a flat disk, as did many of his contemporaries. One of the first estimates of the radius of the Earth was made by Eratosthenes . The first rigorous system of latitude and longitude lines
6320-575: Is subject to the prevailing wind , and is thus the wetter (see orographic precipitation ). The leeward side is the side distant from or physically in the lee of the prevailing wind, and typically the drier. In an archipelago windward islands are upwind and leeward islands are downwind of the prevailing winds, such as the trade winds of the Atlantic and Pacific oceans. Geography Geography (from Ancient Greek γεωγραφία geōgraphía ; combining gê 'Earth' and gráphō 'write')
6478-487: 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
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6636-453: 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
6794-536: Is the study of earth's seasons, climate , atmosphere , soil , streams, landforms, and oceans. Physical geographers will often work in identifying and monitoring the use of natural resources. Human geography (or anthropogeography) is a branch of geography that focuses on studying patterns and processes that shape human society. It encompasses the human, political, cultural , social, and economic aspects. In industry, human geographers often work in city planning, public health, or business analysis. Various approaches to
6952-542: Is the study of the lands, features, inhabitants, and phenomena of Earth . Geography is an all-encompassing discipline that seeks an understanding of Earth and its human and natural complexities —not merely where objects are, but also how they have changed and come to be. While geography is specific to Earth, many concepts can be applied more broadly to other celestial bodies in the field of planetary science . Geography has been called "a bridge between natural science and social science disciplines." Origins of many of
7110-457: 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
7268-455: Is tilted with respect to the perpendicular to its orbital plane around 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
7426-520: The Earth radius was only 16.8 km less than the modern value of 6,356.7 km. In contrast to his predecessors, who measured the Earth's circumference by sighting the Sun simultaneously from two different locations, al-Biruni developed a new method of using trigonometric calculations based on the angle between a plain and mountain top, which yielded more accurate measurements of the Earth's circumference, and made it possible for it to be measured by
7584-583: 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
7742-528: The National Council for Geographic Education and the Association of American Geographers in 1984. These themes are Location, place, relationships within places (often summarized as Human-Environment Interaction), movement, and regions. The five themes of geography have shaped how American education approaches the topic in the years since. Just as all phenomena exist in time and thus have
7900-759: 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
8058-628: The Royal Danish Geographical Society in 1876 and the National Geographic Society in 1888. The influence of Immanuel Kant , Alexander von Humboldt , Carl Ritter , and Paul Vidal de la Blache can be seen as a major turning point in geography from philosophy to an academic subject. Geographers such as Richard Hartshorne and Joseph Kerski have regarded both Humboldt and Ritter as the founders of modern geography, as Humboldt and Ritter were
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#17327654042048216-664: The Spatial or Locational Tradition, the Man-Land or Human-Environment Interaction Tradition (sometimes referred to as Integrated geography ), the Area Studies or Regional Tradition, and the Earth Science Tradition. These concepts are broad sets of geography philosophies bound together within the discipline. They are one of many ways geographers organize the major sets of thoughts and philosophies within
8374-419: 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
8532-472: The built environment and how humans create, view, manage, and influence space. Physical geography examines the natural environment and how organisms , climate, soil , water, and landforms produce and interact. The difference between these approaches led to the development of integrated geography , which combines physical and human geography and concerns the interactions between the environment and humans. Technical geography involves studying and developing
8690-415: 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
8848-470: The first law of geography , "everything is related to everything else, but near things are more related than distant things." This law summarizes the first assumption geographers make about the world. The discipline of geography, especially physical geography, and geology have significant overlap. In the past, the two have often shared academic departments at universities, a point that has led to conflict over resources. Both disciplines do seek to understand
9006-607: The interpolation (estimate) of unmeasured points. Geographers are making notable contributions to the method of quantitative techniques. Qualitative methods in geography are descriptive rather than numerical or statistical in nature. They add context to concepts, and explore human concepts like beliefs and perspective that are difficult or impossible to quantify. Human geography is much more likely to employ qualitative methods than physical geography. Increasingly, technical geographers are attempting to employ GIS methods to qualitative datasets. Qualitative cartography employs many of
9164-452: The lithosphere , atmosphere , hydrosphere , and biosphere . Places do not exist in a vacuum and instead have complex spatial relationships with each other, and place is concerned how a location is situated in relation to all other locations. As a discipline then, the term place in geography includes all spatial phenomena occurring at a location, the diverse uses and meanings humans ascribe to that location, and how that location impacts and
9322-408: 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
9480-643: The points of sail they create) are important factors to consider in such wind-powered or wind-impacted activities as sailing , wind-surfing , gliding , hang-gliding , and parachuting . Other terms with broadly the same meaning are widely used, particularly upwind and downwind . Among sailing craft, the windward vessel is normally the more maneuverable. For this reason, rule 12 of the International Regulations for Preventing Collisions at Sea , applying to sailing vessels, stipulates that where two are sailing in similar directions in relation to
9638-430: 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
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#17327654042049796-506: The quantitative revolution , and critical geography . The strong interdisciplinary links between geography and the sciences of geology and botany , as well as economics, sociology, and demographics , have also grown greatly, especially as a result of earth system science that seeks to understand the world in a holistic view. New concepts and philosophies have emerged from the rapid advancement of computers, quantitative methods, and interdisciplinary approaches. In 1970, Waldo Tobler proposed
9954-546: The rocks on the Earth's surface and the processes that change them over time. Geology employs many of the tools and techniques of technical geographers, such as GIS and remote sensing to aid in geological mapping . However, geology includes research that goes beyond the spatial component, such as the chemical analysis of rocks and biogeochemistry . The discipline of History has significant overlap with geography, especially human geography. Like geology, history and geography have shared university departments. Geography provides
10112-413: 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
10270-461: The "Balkhī school" of terrestrial mapping in Baghdad . Suhrāb, a late tenth century Muslim geographer accompanied a book of geographical coordinates, with instructions for making a rectangular world map with equirectangular projection or cylindrical equidistant projection. Abu Rayhan Biruni (976–1048) first described a polar equi- azimuthal equidistant projection of the celestial sphere . He
10428-464: 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
10586-714: The 17th century advanced ideas and methods of Western-style geography were adopted in China. During the Middle Ages , the fall of the Roman empire led to a shift in the evolution of geography from Europe to the Islamic world . Muslim geographers such as Muhammad al-Idrisi produced detailed world maps (such as Tabula Rogeriana ), while other geographers such as Yaqut al-Hamawi , Abu Rayhan Biruni , Ibn Battuta , and Ibn Khaldun provided detailed accounts of their journeys and
10744-484: 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
10902-470: The Earth for automatic retrieval by a computer in an accurate manner appropriate to the information's purpose. In addition to all of the other subdisciplines of geography, GIS specialists must understand computer science and database systems. GIS has revolutionized the field of cartography: nearly all mapmaking is now done with the assistance of some form of GIS software . The science of using GIS software and GIS techniques to represent, analyse, and predict
11060-493: The Earth most effectively and behavioural psychology to induce the readers of their maps to act on the information. They must learn geodesy and fairly advanced mathematics to understand how the shape of the Earth affects the distortion of map symbols projected onto a flat surface for viewing. It can be said, without much controversy, that cartography is the seed from which the larger field of geography grew. Geographic information systems (GIS) deal with storing information about
11218-529: The Earth's land surface , ocean, and atmosphere, because it: (a) supplies objective information at a variety of spatial scales (local to global), (b) provides a synoptic view of the area of interest, (c) allows access to distant and inaccessible sites, (d) provides spectral information outside the visible portion of the electromagnetic spectrum , and (e) facilitates studies of how features/areas change over time. Remotely sensed data may be analyzed independently or in conjunction with other digital data layers (e.g., in
11376-424: The Earth's surface, the activity and use that occurs, has occurred, and will occur at the coordinates, and the meaning ascribed to the space by human individuals and groups. This can be extraordinarily complex, as different spaces may have different uses at different times and mean different things to different people. In physical geography, a place includes all of the physical phenomena that occur in space, including
11534-654: 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] )
11692-593: 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
11850-758: The Moon always face Earth with the same side. Earth, like most other bodies in 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
12008-426: 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
12166-458: 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 ,
12324-403: 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
12482-507: The art, science, and technology of making maps. Cartographers study the Earth's surface representation with abstract symbols (map making). Although other subdisciplines of geography rely on maps for presenting their analyses, the actual making of maps is abstract enough to be regarded separately. Cartography has grown from a collection of drafting techniques into an actual science. Cartographers must learn cognitive psychology and ergonomics to understand which symbols convey information about
12640-425: 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
12798-458: The book expanded on these key concepts by adding "Environmental systems," "Social Systems," "Nature," " Globalization ," "Development," and "Risk," demonstrating how challenging narrowing the field can be. Another approach used extensively in teaching geography are the Five themes of geography established by "Guidelines for Geographic Education: Elementary and Secondary Schools," published jointly by
12956-406: The broad discipline of geography by serving as a set of unique methods for managing the interdisciplinary nature of the phenomena under investigation. While human and physical geographers use the techniques employed by technical geographers, technical geography is more concerned with the fundamental spatial concepts and technologies than the nature of the data. It is therefore closely associated with
13114-450: 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
13272-438: The concept of spacetime . Geography is subject to the laws of physics, and in studying things that occur in space, time must be considered. Time in geography is more than just the historical record of events that occurred at various discrete coordinates; but also includes modeling the dynamic movement of people, organisms, and things through space. Time facilitates movement through space, ultimately allowing things to flow through
13430-424: The concepts in geography can be traced to Greek Eratosthenes of Cyrene, who may have coined the term "geographia" ( c. 276 BC – c. 195/194 BC ). The first recorded use of the word γεωγραφία was as the title of a book by Greek scholar Claudius Ptolemy (100 – 170 AD). This work created the so-called "Ptolemaic tradition" of geography, which included "Ptolemaic cartographic theory." However,
13588-468: The concepts of geography (such as cartography ) date back to the earliest attempts to understand the world spatially, with the earliest example of an attempted world map dating to the 9th century BCE in ancient Babylon . The history of geography as a discipline spans cultures and millennia, being independently developed by multiple groups, and cross-pollinated by trade between these groups. The core concepts of geography consistent between all approaches are
13746-405: The context of a map is the ratio between a distance measured on the map and the corresponding distance as measured on the ground. This concept is fundamental to the discipline of geography, not just cartography, in that phenomena being investigated appear different depending on the scale used. Scale is the frame that geographers use to measure space, and ultimately to understand a place. During
13904-454: 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
14062-616: 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
14220-419: 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
14378-527: 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
14536-463: 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
14694-539: 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
14852-452: The different historical approach theories geographers have taken to the discipline. In contrast, geography's branches describe contemporary applied geographical approaches. Geography is an extremely broad field. Because of this, many view the various definitions of geography proposed over the decades as inadequate. To address this, William D. Pattison proposed the concept of the "Four traditions of Geography" in 1964. These traditions are
15010-399: The discipline during the quantitative revolution of the 1950s and 60s. These methods revitalized the discipline in many ways, allowing scientific testing of hypotheses and proposing scientific geographic theories and laws. The quantitative revolution heavily influenced and revitalized technical geography, and lead to the development of the subfield of quantitative geography. Cartography is
15168-514: The discipline into a section containing content such as cartographic techniques and globes. There are several other terms, often used interchangeably with technical geography to subdivide the discipline, including "techniques of geographic analysis," "Geographic Information Technology," "Geography method's and techniques," " Geographic Information Science ," " geoinformatics ," " geomatics ," and "information geography". There are subtle differences to each concept and term; however, technical geography
15326-458: The discipline of geography is normally concerned with the Earth, the term can also be informally used to describe the study of other worlds, such as the planets of the Solar System and even beyond. The study of systems larger than the Earth itself usually forms part of Astronomy or Cosmology . The study of other planets is usually called planetary science . Alternative terms such as areography (geography of Mars) have been employed to describe
15484-552: The discipline. In another approach to the abovementioned four traditions, geography is organized into applied branches. The UNESCO Encyclopedia of Life Support Systems organizes geography into the three categories of human geography , physical geography , and technical geography . Some publications limit the number of branches to physical and human, describing them as the principal branches. Geographers rarely focus on just one of these topics, often using one as their primary focus and then incorporating data and methods from
15642-611: 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
15800-407: The emerging category. These branches use similar geographic philosophies, concepts, and tools and often overlap significantly. Physical geography (or physiography) focuses on geography as an Earth science . It aims to understand the physical problems and the issues of lithosphere , hydrosphere , atmosphere , pedosphere , and global flora and fauna patterns ( biosphere ). Physical geography
15958-544: 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
16116-518: The first to establish geography as an independent scientific discipline. Over the past two centuries, the advancements in technology with computers have led to the development of geomatics and new practices such as participant observation and geostatistics being incorporated into geography's portfolio of tools. In the West during the 20th century, the discipline of geography went through four major phases: environmental determinism , regional geography ,
16274-504: The geography of the regions they visited. Turkish geographer Mahmud al-Kashgari drew a world map on a linguistic basis, and later so did Piri Reis ( Piri Reis map ). Further, Islamic scholars translated and interpreted the earlier works of the Romans and the Greeks and established the House of Wisdom in Baghdad for this purpose. Abū Zayd al-Balkhī , originally from Balkh , founded
16432-638: 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
16590-404: 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
16748-449: The heights of mountains, depths of the valleys , and expanse of the horizon . He also discussed human geography and the planetary habitability of the Earth. He also calculated the latitude of Kath, Khwarezm , using the maximum altitude of the Sun, and solved a complex geodesic equation to accurately compute the Earth's circumference , which was close to modern values of the Earth's circumference. His estimate of 6,339.9 km for
16906-600: The history of the discipline is a series of competing narratives, with concepts emerging at various points across space and time. The oldest known world maps date back to ancient Babylon from 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
17064-406: 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
17222-513: 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
17380-535: The late 13th century. Additionally, "wind" has been used figuratively in phrases like "which way the wind blows" to indicate the current state of affairs. The suffix "-ward," meaning "toward," is an adverbial suffix in Old English derived from Proto-Germanic *werda-, which itself comes from the PIE root *wer- meaning "to turn, bend." The original notion of "-ward" is "turned toward." Windward and leeward directions (and
17538-402: The laws of nature and to mark their influences upon man. This is 'a description of the world'—that is Geography. In a word, Geography is a Science—a thing not of mere names but of argument and reason, of cause and effect. Geography as a discipline can be split broadly into three main branches: human geography , physical geography , and technical geography . Human geography largely focuses on
17696-669: The leeward side it blocks. The drier leeward area is said to be in a rain shadow . The term "windward" has roots in both Low German and Old English. The word "lee", which means a place without wind, comes from the Old Norse "hle" for "cover" and has been used in marine navigation in Germany since medieval times. The word "wind," meaning "air in motion," comes from Proto-Germanic *winda- and has evolved over time, with pronunciation changes influenced by similar words like "windy." The word "wind" has been associated with emptiness and vanity since
17854-399: 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
18012-410: 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
18170-456: 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
18328-497: 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
18486-409: 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
18644-483: 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
18802-417: 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
18960-612: 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
19118-548: 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
19276-399: 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,
19434-424: 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
19592-425: 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
19750-593: 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
19908-670: 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
20066-599: 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
20224-414: The other branches. Often, geographers are asked to describe what they do by individuals outside the discipline and are likely to identify closely with a specific branch, or sub-branch when describing themselves to lay people. Human geography studies people and their communities, cultures, economies, and environmental interactions by studying their relations with and across space and place. Physical geography
20382-649: 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
20540-474: 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
20698-501: 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
20856-478: 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,
21014-400: The planet. The water vapor acts as a greenhouse gas and, together with other greenhouse gases in 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
21172-421: 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
21330-402: The prediction of eclipses. The foundations of geography can be traced to ancient cultures, such as the ancient, medieval, and early modern Chinese . The Greeks , who were the first to explore geography as both art and science, achieved this through Cartography , Philosophy , and Literature , or through Mathematics . There is some debate about who was the first person to assert that the Earth
21488-495: 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
21646-457: The quantitative revolution, geography shifted to an empirical law-making ( nomothetic ) approach. Several laws of geography have been proposed since then, most notably by Waldo Tobler and can be viewed as a product of the quantitative revolution. In general, some dispute the entire concept of laws in geography and the social sciences. These criticisms have been addressed by Tobler and others, such as Michael Frank Goodchild . However, this
21804-493: 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
21962-473: The relationship between physical and human phenomena and their spatial patterns. Names of places...are not geography...To know by heart a whole gazetteer full of them would not, in itself, constitute anyone a geographer. Geography has higher aims than this: it seeks to classify phenomena (alike of the natural and of the political world, in so far as it treats of the latter), to compare, to generalize, to ascend from effects to causes, and, in doing so, to trace out
22120-438: The same software and techniques as quantitative cartography. It may be employed to inform on map practices, or to visualize perspectives and ideas that are not strictly quantitative in nature. An example of a form of qualitative cartography is a Chorochromatic map of nominal data, such as land cover or dominant language group in an area. Another example is a deep map , or maps that combine geography and storytelling to produce
22278-533: The second and replaced with another. A few of the proposed laws of geography are below: Additionally, several variations or amendments to these laws exist within the literature, although not as well supported. For example, one paper proposed an amended version of Tobler's first law of geography, referred to in the text as the Tobler–von Thünen law , which states: "Everything is related to everything else, but near things are more related than distant things, as
22436-522: 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
22594-445: The spatial context within which historical events unfold. The physical geographic features of a region, such as its landforms, climate, and resources, shape human settlements, trade routes, and economic activities, which in turn influence the course of historical events. Thus, a historian must have a strong foundation in geography. Historians employ the techniques of technical geographers to create historical atlases and maps. While
22752-675: The spatial relationships is called geographic information science (GISc). Remote sensing is the art, science, and technology of obtaining information about Earth's features from measurements made at a distance. Remotely sensed data can be either passive, such as traditional photography , or active, such as LiDAR . A variety of platforms can be used for remote sensing, including satellite imagery , aerial photography (including consumer drones), and data obtained from hand-held sensors. Products from remote sensing include Digital elevation model and cartographic base maps. Geographers increasingly use remotely sensed data to obtain information about
22910-538: The spatial tradition of geography while being applied to the other two major branches. A technical geographer might work as a GIS analyst, a GIS developer working to make new software tools, or create general reference maps incorporating human and natural features. All geographic research and analysis start with asking the question "where," followed by "why there." Geographers start with the fundamental assumption set forth in Tobler's first law of geography , that "everything
23068-403: The study of human geography have also arisen through time and include: Technical geography concerns studying and developing tools, techniques, and statistical methods employed to collect, analyze, use, and understand spatial data. Technical geography is the most recently recognized, and controversial, of the branches. Its use dates back to 1749, when a book published by Edward Cave organized
23226-547: The study of other celestial objects. Ultimately, geography may be considered a subdiscipline within planetary science. Earth Earth 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
23384-572: The times when geography became recognized as a discrete academic discipline , and became part of a typical university curriculum in Europe (especially Paris and Berlin ). The development of many geographic societies also occurred during the 19th century, with the foundations of the Société de Géographie in 1821, the Royal Geographical Society in 1830, Russian Geographical Society in 1845, American Geographical Society in 1851,
23542-494: The tools and techniques used by geographers, such as remote sensing, cartography, and geographic information system. Narrowing down geography to a few key concepts is extremely challenging, and subject to tremendous debate within the discipline. In one attempt, the 1st edition of the book "Key Concepts in Geography" broke down this into chapters focusing on "Space," "Place," "Time," "Scale," and "Landscape." The 2nd edition of
23700-401: The view of the world as a photograph, with everything frozen in place when the coordinates were recorded. Today, geographers are trained to recognize the world as a dynamic space where all processes interact and take place, rather than a static image on a map. Place is one of the most complex and important terms in geography. In human geography, place is the synthesis of the coordinates on
23858-453: The wind is going. The side of a ship that is towards the leeward is its "lee side". If the vessel is heeling under the pressure of crosswind , the lee side will be the "lower side". During the Age of Sail , the term weather was used as a synonym for windward in some contexts, as in the weather gage . Since it captures rainfall , the windward side of a mountain tends to be wetter than
24016-402: The wind, the windward vessel gives way to the leeward vessel. In naval warfare during the Age of Sail , a vessel always sought to use the wind to its advantage, maneuvering if possible to attack from windward. This was particularly important for less maneuverable square-rigged warships, which had limited ability to sail upwind, and sought to "hold the weather gage " entering battle. This
24174-461: 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
24332-620: 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
24490-615: Was finding the latitude and longitude of a geographic location. While the problem of latitude was solved long ago, but that of longitude remained; agreeing on what zero meridians should be was only part of the problem. It was left to John Harrison to solve it by inventing the chronometer H-4 in 1760, and later in 1884 for the International Meridian Conference to adopt by convention the Greenwich meridian as zero meridians. The 18th and 19th centuries were
24648-404: Was particularly important once artillery was introduced to naval warfare. Ships heel away from the wind, so the leeward vessel would expose more of her topsides to shot, in extreme cases even part of her bottom. The terms windward and leeward are used in reference both to sides (and climates) of individual islands and relative island locations in an archipelago . The windward side of an island
24806-551: Was published by Bernhardus Varenius , which was later edited and republished by others including Isaac Newton . This textbook sought to integrate new scientific discoveries and principles into classical geography and approach the discipline like the other sciences emerging, and is seen by some as the division between ancient and modern geography in the West. The Geographia Generalis contained both theoretical background and practical applications related to ship navigation. The remaining problem facing both explorers and geographers
24964-523: Was 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 the Indian subcontinent . He often combined astronomical readings and mathematical equations to develop methods of pin-pointing locations by recording degrees of latitude and longitude . He also developed similar techniques when it came to measuring
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