The geographical centre of Earth is the geometric centre of all land surfaces on Earth. Geometrically defined it is the centroid of all land surfaces within the two dimensions of the Geoid surface which approximates the Earth's outer shape. The term centre of minimum distance [1] specifies the concept more precisely as the domain is the sphere surface without boundary and not the three-dimensional body.
Explained in a different way, it is the location on the surface of Earth where the sum of distances to all locations on land is the smallest. Assuming an airplane with infinite energy and resources, if one were to fly from one start location to any location on land and back again, and repeat this from the same start location to all possible destinations, the starting location where the total travel distance is the smallest would be the geographical centre of Earth.
Its distance definition follows the shortest path on the surface of Earth along the great circle (orthodrome).
Around the world throughout history many real and illusive places were identified as axis mundi or centers of the world.
In 1864, Charles Piazzi Smyth, Astronomer Royal for Scotland, gave in his book Our Inheritance in the Great Pyramid the coordinates with 30°00′N31°00′E / 30.000°N 31.000°E , the location of the Great Pyramid of Giza in Egypt. [3] [4] He stated that this had been calculated by "carefully summing up all the dry land habitable by man all the wide world over". [3]
In October of that year, Smyth proposed to position the prime meridian at the longitude of the Great Pyramid because there it would "pass over more land than [at] any other [location]". [5] He also argued the cultural significance of the location and its vicinity to Jerusalem. The expert committee deciding the issue, however, voted for Greenwich because "so many ships used the port of London". [4]
In 1973, Andrew J. Woods, a physicist with Gulf Energy and Environmental Systems in San Diego, California, used a digital global map and calculated the coordinates on a mainframe system as 39°00′N34°00′E / 39.000°N 34.000°E , in modern-day Turkey, near the district of Kırşehir, Seyfe Village approx. 1,800 km north of Giza. [2] In 2003, a new calculation based on a global digital elevation model obtained from satellite measurements, ETOPO2, whose data points are spaced 2′ (3.7 km at the equator) led to the result ♁ 41° N, 35° E and thus validating Woods's calculation. [6]
Various definitions of geographical centres exists. The definitions used by the references in this article refer to calculations within the 2 dimensions of a surface, mainly as the surface of Earth is the domain of human cultural existence. Other definitions refer to calculations based on three-dimensional objects, for example the Newtonian gravity centre of the whole Earth (physical barycentre) or the Newtonian gravity centre of only the continents as uniform thick three-dimensional objects. Those centres can be found inside Earth mostly near its core. A projection of those centres towards the surface would be then an alternative definition of the geographical centre, some of those calculations [8] result in a surface location projection not that far away from the geographical centre.
Geodesy or geodetics is the science of measuring and representing the geometry, gravity, and spatial orientation of the Earth in temporally varying 3D. It is called planetary geodesy when studying other astronomical bodies, such as planets or circumplanetary systems. Geodesy is an earth science and many consider the study of Earth's shape and gravity to be central to that science. It is also a discipline of applied mathematics.
In geography, latitude is a coordinate that specifies the north–south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at the south pole to 90° at the north pole, with 0° at the Equator. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth.
Longitude is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians are imaginary semicircular lines running from pole to pole that connect points with the same longitude. The prime meridian defines 0° longitude; by convention the International Reference Meridian for the Earth passes near the Royal Observatory in Greenwich, south-east London on the island of Great Britain. Positive longitudes are east of the prime meridian, and negative ones are west.
A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude. It is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system, the geographic coordinate system is not cartesian because the measurements are angles and are not on a planar surface.
Charles Piazzi Smyth was a British astronomer who was Astronomer Royal for Scotland from 1846 to 1888; he is known for many innovations in astronomy and, along with his wife Jessica Duncan Piazzi Smyth, his pyramidological and metrological studies of the Great Pyramid of Giza.
A circle of latitude or line of latitude on Earth is an abstract east–west small circle connecting all locations around Earth at a given latitude coordinate line.
A projected coordinate system – also called a projected coordinate reference system, planar coordinate system, or grid reference system – is a type of spatial reference system that represents locations on Earth using Cartesian coordinates (x, y) on a planar surface created by a particular map projection. Each projected coordinate system, such as "Universal Transverse Mercator WGS 84 Zone 26N," is defined by a choice of map projection (with specific parameters), a choice of geodetic datum to bind the coordinate system to real locations on the earth, an origin point, and a choice of unit of measure. Hundreds of projected coordinate systems have been specified for various purposes in various regions.
In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle east or west of a given prime meridian. In other words, it is a coordinate line for longitudes, a line of longitude. The position of a point along the meridian at a given longitude is given by its latitude, measured in angular degrees north or south of the Equator. On a Mercator projection or on a Gall-Peters projection, each meridian is perpendicular to all circles of latitude. Assuming a spherical Earth, a meridian is a great semicircle on Earth's surface. Adopting instead a spheroidal or ellipsoid model of Earth, the meridian is half of a north-south great ellipse. The length of a meridian is twice the length of an Earth quadrant, equal to 20,003.93 km (12,429.87 mi) on a modern ellipsoid.
The pyramid inch is a now discredited unit of measure formerly claimed by pyramidologists to have been used in ancient times.
Kırşehir Province is a province in central Turkey, forming part of the Central Anatolia Region. Its area is 6,584 km2, and its population is 244,519 (2022). The average elevation is approximately 985 meters above sea level. The provincial capital is Kırşehir. The geographical centre of all land surfaces on Earth is at 39°00′N34°00′E, in Kırşehir Province, Turkey.
In demographics, the center of population of a region is a geographical point that describes a centerpoint of the region's population. There are several ways of defining such a "center point", leading to different geographical locations; these are often confused.
The equirectangular projection, and which includes the special case of the plate carrée projection, is a simple map projection attributed to Marinus of Tyre, who Ptolemy claims invented the projection about AD 100.
Address geocoding, or simply geocoding, is the process of taking a text-based description of a location, such as an address or the name of a place, and returning geographic coordinates, frequently latitude/longitude pair, to identify a location on the Earth's surface. Reverse geocoding, on the other hand, converts geographic coordinates to a description of a location, usually the name of a place or an addressable location. Geocoding relies on a computer representation of address points, the street / road network, together with postal and administrative boundaries.
Pyramidology refers to various religious or pseudoscientific speculations regarding pyramids, most often the Giza pyramid complex and the Great Pyramid of Giza in Egypt. Some "pyramidologists" also concern themselves with the monumental structures of pre-Columbian America, and the temples of Southeast Asia.
In geography, the centroid of the two-dimensional shape of a region of the Earth's surface is known as its geographic centre or geographical centre or gravitational centre. Informally, determining the centroid is often described as finding the point upon which the shape would balance. This method is also sometimes described as the "gravitational method".
In cartography, the normal cylindrical equal-area projection is a family of normal cylindrical, equal-area map projections.
The geo URI scheme is a Uniform Resource Identifier (URI) scheme defined by the Internet Engineering Task Force's RFC 5870 as:
a Uniform Resource Identifier (URI) for geographic locations using the 'geo' scheme name. A 'geo' URI identifies a physical location in a two- or three-dimensional coordinate reference system in a compact, simple, human-readable, and protocol-independent way.
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data. It is split across two articles:
Centre points of Australia are those geographical locations that have been considered to be centre of Australia, as distinct from the extreme points of Australia.