geography Geography (from Ancient Greek ; combining 'Earth' and 'write', literally 'Earth writing') is the study of the lands, features, inhabitants, and phenomena of Earth. Geography is an all-encompassing discipline that seeks an understanding o ...

, 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 figure. The same definition extends to any object in n-d ...

of the two-dimensional shape of a region of the Earth's surface (projected radially to sea level or onto a geoid 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 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), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...

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, a map projection is any of a broad set of Transformation (function) , transformations employed to represent the curved two-dimensional Surface (mathematics), surface of a globe on a Plane (mathematics), plane. In a map projection, ...

to use.

Notable geographical centres

* Geographical centre of Earth * Axis mundi * Omphalos of Delphi

Geographic centres in Africa

* Geographic Centre of Uganda (Amolatar Monument)

Geographic centres in Asia

* Geographical midpoints of Asia, in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

* 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 (Nil-Saint-Vincent-Saint-Martin) * Geographical centre of Estonia (Paenasti) * Geographical centre of Germany (Niederdorla) ** Central Germany (geography) * Geographical centre of Hungary (Pusztavacs) *

Geographical centre of Ireland The Geographical Centre of Ireland, according to an investigation and calculation carried out by the Official Irish Government Mapping Agency, Ordnance Survey Ireland (OSI) published on the official OSI website on 24 February 2022 is near the ...

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 This is a list of Geographical centre, geographic centers of each U.S. state and inhabited Territories of the United States, territory. The geographic center of the United States is northeast of Belle Fourche, South Dakota, Belle Fourche in Butte C ...

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

External links

* {{Set index article