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 term center of minimum distance[1] specifies the concept more precisely as the domain is the sphere surface without boundary and not the sphere as three-dimensional body.

For the geological center of the planet, see Earth's inner core.

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. If you had an airplane with an infinite energy resource and fly from one start location on Earth to one location on a land surface somewhere on Earth and back again and repeat that from the same start location to all possible destination locations, the starting locations where the total travel distance sums up as the smallest, marks the geographical center of Earth.

Its distance definition follows the shortest path on the surface of Earth along the great circle (orthodrome).

History of the concept
Geographical centre of Earth is located in Earth
Geographical centre of Earth
Andrew J. Woods's 1974 calculation[2] of the geographical center of all land surfaces on Earth: Kırṣehir, Seyfe Village Turkey.
Geographical centre of Earth is located in Middle East
Geographical centre of Earth
Geographical centre of Earth (Middle East)
Geographical centre of Earth is located in Earth
Geographical centre of Earth
Charles Piazzi Smyth's 1864 definition of the geographical center of Earth: Giza, Egypt.[3]
Geographical centre of Earth is located in Middle East
Geographical centre of Earth
Geographical centre of Earth (Middle East)

In 1864, Charles Piazzi Smyth, Astronomer Royal for Scotland, gave in his book Our Inheritance in the Great Pyramid the coordinates with 30°00′N 31°00′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′N 34°00′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 Wood's calculation.[6]

Differentiation from other definitions and calculations

Various definitions of geographical centers exists. The definition 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 center of the whole Earth (physical barycenter) or the Newtonian gravity center of only the continents as uniform thick three-dimensional objects. Those centers can be found inside Earth mostly near its core. A projection of those centers towards the surface would be then an alternative definition of the geographical center, some of those calculations[7] result in a surface location projection not that far away from the geographical center.

See also

References
  1. "Geo mid point: Calculation Methods". 2022. Retrieved 16 September 2022.
  2. Woods, Andrew J. (1973). The Center of the Earth. I.C.R. Technical Monographs. Vol. 3. London: I.C.R.
  3. Smyth, Charles Piazzi (1864). Our inheritance in the Great Pyramid. London: W. Isbister & Co. pp. V, 55, 460.
  4. Wilson, Colin; Rand Flem-Ath (2002). The Atlantis Blueprint: Unlocking The Ancient Mysteries Of A Long-Lost Civilization. Random House Digital, Inc. pp. 63–64. ISBN 9780307481757. Retrieved 4 May 2012.
  5. Smyth, Charles Piazzi (1873). Royal Scottish Society of Arts (ed.). "On an Equal-Surface Projection for Maps of the World, and its Application to Certain Anthropological Questions". Transactions of the Royal Scottish Society of Arts. Edinburgh: Neill & Company. 8: 205–208, 213.
  6. Isenberg, Holger (2003). "Giza, Center of Earth". mars-news.de. Retrieved 27 December 2022.
  7. Huber, W (17 January 2014). "What is Centroid of all lands of Earth?" [Where is the center of continental land area]. Stack Exchange. GIS.
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