geography Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, a ...

, the

centroid In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the arithmetic mean position of all the points in the surface of the figure. The same definition extends to any ...

of the two-dimensional shape of a region of the Earth's surface (projected radially to sea level or onto a

geoid The geoid () is the shape that the ocean surface would take under the influence of the gravity of Earth, including gravitational attraction and Earth's rotation, if other influences such as winds and tides were absent. This surface is exten ...

surface) is known as its geographic centre or geographical centre or (less commonly) gravitational centre. Informally, determining the centroid is often described as finding the point upon which the shape (cut from a uniform plane) would balance. This method is also sometimes described as the "gravitational method". One example of a refined approach using an azimuthal equidistant projection, also potentially incorporating an iterative process, was described by Peter A. Rogerson in 2015. The abstract says "the new method minimizes the sum of squared great circle distances from all points in the region to the center". However, as that property is also true of a centroid (of area), this aspect is effectively just different terminology for determining the centroid. In 2019, New Zealand's

GNS Science GNS Science ( mi, Te Pū Ao), officially registered as the Institute of Geological and Nuclear Sciences Limited, is a New Zealand Crown Research Institute. It focuses on geology, geophysics (including seismology and volcanology), and nuclear sc ...

also used an iterative approach (and a variety of different projections) when determining a centre position for New Zealand's Extended Continental Shelf. However, other methods have also been proposed or used to determine the centres of various countries and regions. These include: * centroid of volume (incorporating elevations into calculations), instead of the more usual centroid of area as described above. * centre point of a bounding box completely enclosing the area. While relatively easy to determine, a centre point calculated using this method will generally also vary (relative to the shape of the landmass or region) depending on the orientation of the bounding box to the area under consideration. In this sense it is not a robust method. * finding the longitude that divides the region into two equal area parts to the east and west, and then similarly the latitude that divides the region into two equal area parts to the north and south. Like the bounding box approach described above this method would not generally locate precisely the same point if the same shaped region was oriented differently. As noted in a

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

document, "There is no generally accepted definition of geographic center, and no completely satisfactory method for determining it." In general, there is room for debate around various details such as whether or not to include islands and similarly, large bodies of water, how best to handle the curvature of the Earth (a more significant factor with larger regions) and closely related to that issue, which

map projection In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longit ...

to use.

Notable geographical centres

Geographical centre of Earth The geographical center of Earth is the geometric center 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 ...

Axis mundi In astronomy, axis mundi is the Latin term for the axis of Earth between the celestial poles. In a geocentric coordinate system, this is the axis of rotation of the celestial sphere. Consequently, in ancient Greco-Roman astronomy, the ''a ...

* Omphalos of Delphi

Geographic centres in Africa

* Geographic Centre of Uganda (Amolatar Monument)

Geographic centres in Asia

* Geographical midpoints of Asia, in China or

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eigh ...

* Geographical centre of India ** Zero Mile Stone (Nagpur) * Geographic center of Iran * Geographic centre of Sri Lanka * Geographical centre of the Korean Peninsula * Geographical centre of the Philippines * Geographical centre of the Russian Federation * Geographical centre of the Soviet Union * Geographic center of Taiwan

Geographic centres in Europe

* Geographical midpoint of Europe * Geographical centre of Austria * Geographic center of Belarus * Geographical centre of Belgium * Geographical centre of Estonia * Geographical centre of Germany **

Central Germany (geography) Central Germany (''Zentraldeutschland''/''Mitteldeutschland''), in geography, describes the areas surrounding the geographical centre of Germany. Hesse, Saxony-Anhalt and Thuringia are the only landlocked German states without an international ...

* Geographical centre of Hungary * Geographical centre of Ireland * Geographical centre of Lithuania * Geographical centre of Norway * Geographical centre of Poland * Geographical center of Romania * Geographical centre of the Russian Federation * Geographical centre of Serbia * Geographical centre of Slovenia * Geographical centre of the Soviet Union *

Geographical center of Sweden The geographical center of Sweden is contested amongst at least four locations. Flataklocken The oldest and most famous geographical center of Sweden is Flataklocken, a spot next to Lake Munkby in Torpshammar, Medelpad at . The site was identifi ...

Geographical centre of Switzerland The geographical centre of Switzerland has the coordinates (Swiss Grid: 660158/183641). It is located at Älggi-Alp in the municipality of Sachseln, Obwalden. The point is the centre of mass determined in 1988 by Swisstopo. As the point is dif ...

* Centre points of the United Kingdom ** Geographical centre of Great Britain **

Centre points of counties of the United Kingdom The following is a list of geographical centre points of counties of the United Kingdom. The data has been taken from the Ordnance Survey'sGB Counties - Past and Present dataset, under an Open Government Licence (OGL). The coordinates were calcula ...

** Geographic centre of England **

Geographical centre of Scotland There is some debate as to the location of the geographical centre of Scotland. This is due to different methods of calculating the centre, and whether surrounding islands are included. Centre of gravity method In 2002, the Ordnance Survey calc ...

** Geographic centre of Wales

Geographic centres in North America

* Geographic center of North America * Geographic centre of Canada * Geographic center of the United States ** List of geographic centers of the United States

Geographic centres in Oceania

* Centre points of Australia * Geographic centre of New Zealand

Geographic centres in South America

* Geographical Center of South America * Geographical Center of Colombia

References

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