Center of the earth's surface
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The geographic center of the earth's surface is the geometric center of gravity of all land areas on earth . This is located near the city of Çorum in Turkey.
Formulated geometrically more precisely, it is the center of gravity within the two-dimensional spherical surface of the earth, whereby a geoid is assumed as a geometric shape for simplicity and the relief structure of the land areas is idealized as flat planes. To calculate a centroid, a definition of distance is necessary, which is given on the earth's surface as the shortest connection between two points over the great arc . The real distance between two points on earth is therefore clear and independent of any map projection .
The term does not mean the geometric center of the earth as a three-dimensional body, because it lies within the earth's core.
Calculation method
The geographical center is clearly the point on the earth's surface from which the sum of the distances to all other points on land is minimal. The determination cannot be made mathematically and analytically, ie “in one step”, because there is no mathematical abstraction of the shape of the continents and islands of the earth, but must therefore be carried out numerically iteratively. The method commonly used divides a digital earth model into grid points and calculates the distances to all other grid points for each grid point and adds them up. The point whose sum of distances is minimal is the geographic center.
The same calculation method was used, for example, to determine the center of the population , except that the local population density was used as a basis for calculation.
History of calculation
In 1864, Charles Piazzi Smyth , director of the Scottish Royal Observatory of Edinburgh, in his book Our Inheritance in the Great Pyramid, gave the coordinates as 30 ° N , 31 ° E , which corresponds to the position of the pyramids at Giza . In October of the same year, Smyth added, in order to be able to declare the Great Pyramid as the prime meridian , that this is the meridian which, compared to all others, runs the largest part of the route over land. He also emphasized the cultural importance of this position with its proximity to Jerusalem. The then decision-making body for the selection of the prime meridian then chose the position of the Royal Greenwich Observatory in London in 1884 , because at that time map navigation was mainly used for nautical navigation and London was the most important world port. Referring to Smyth, Frederick Augustus Porter Barnard (1809-1889) wrote in The imaginary metrological system of the Great pyramid of Giza in 1884 that the perfect positioning of the Great Pyramid along the meridian suggests an intended decision by its builder.
In the September 1919 issue of American Trestle Board Magazine , William Galliher stated that the knowledge that the Great Pyramid was the geographic center of all land areas was "solidified through many years of scientific research" and that the geographic position of the Great Pyramid is believed to be the "ultimate Place on earth ”in order to survive a cataclysmic event.
In 1973 Andrew J. Woods, a physicist at Gulf Energy & Environmental Systems Company in San Diego, used a global digital map to algorithmically compute the coordinates on a mainframe system. The result was 39 ° N , 34 ° E 1000 km north of Giza and 300 km east of the longitude given by Smyth.
In 2003, a new calculation based on a global digital elevation model obtained from satellite measurements , ETOPO2, whose data points are 2 ′ apart (3.7 km at the equator), led to the result 41 ° N , 35 ° E and thus validated Wood's calculation .
criticism
The calculation of the geographical center depends on the type of map projection: At first glance, the position of the center near the center of the world maps commonly used in Europe and the USA appears to be determined by the selection of the map section. In the age before the invention of the computer, the center was often determined by drawing on maps in cylinder projection. As a result, the imaging errors caused by every map projection were carried over to the calculation and distance calculations beyond the edge of the map and were probably not carried out. Nowadays, the calculation is done independently of each map by directly determining the distances along great arcs. The computer program uses a digital globe model, ie a "borderless map". The only major error arises from the simplification of the shape of the earth's surface, but this deviation is so minimal that it can be neglected.
The calculation would ignore the surface relief of the earth, i.e. its mountains and depressions: the distance between the highest elevation on the earth's surface above sea level and the deepest depression within continents is 10 km. To clearly illustrate this minimal error: 10 km is 0.08% of the diameter of the earth, which is 12,700 km and thus ignoring the surface details is justified.
The choice of the algorithm chosen for the calculation is arbitrary: The algorithm chosen is the usual method for determining the center points of irregular surfaces. Ideally, it is z. B. the procedure within the business administration department Operations Research to determine the optimal location of a distribution warehouse of a company if there is only one central warehouse and the distribution targets are distributed over the area.
Individual evidence
- ^ Charles Piazzi Smyth : Our inheritance in the Great Pyramid . W. Isbister & Co, London 1864, p. V, 55,460 ( archive.org ).
- ^ A b Colin Wilson , Rand Flem-Ath: The Atlantis Blueprint: Unlocking The Ancient Mysteries Of A Long-Lost Civilization . Random House , 2002, p. 63–64 ( limited preview in Google Book search).
- ^ Frederick Augustus Porter Barnard: The imaginary metrological system of the Great pyramid of Gizeh . John Wiley & Sons , 1884, p. 12–13 ( limited preview in Google Book search).
- ↑ William Galliher: The Riddle of Cheops Pyramid . In: Trestle Board Magazine . tape 33 , no. 3 . Kessinger Publishing , September 1919, p. 9 ( limited preview in Google Book search).
- ^ Andrew J. Woods: The Center of the Earth . In: ICR Technical Monographs . tape 3 . ICR, London 1973 ( icr.org [accessed December 2, 2012]).
- ↑ ETOPO2 Global Gridded 2-minute Database . NOAA. September 1, 2001. Retrieved December 2, 2012.
- ↑ Holger Isenberg: Giseh, center of the earth . October 13, 2003. Retrieved December 2, 2012.
Map with all coordinates: