# Geographic Coordinates Of A Geographic Coordinate System

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A geographic coordinate system is a coordinate system that enables every location on the Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents vertical position, and two or three of the numbers represent horizontal position. A common choice of coordinates is latitude, longitude and elevation. To specify a location on a two-dimensional map requires a map projection. History The invention of a geographic coordinate system is generally credited to Eratosthenes of Cyrene, who composed his now-lost Geography at the Library of Alexandria in the 3rd century BC. A century later, Hipparchus of Nicaea improved upon his system by determining latitude from stellar…show more content…
The Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911. Geographic latitude and longitude The "latitude" of a point on the Earth 's surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of the Earth called parallels, as they are parallel to the equator and to each other. The north pole is 90° N; the south pole is 90° S. The 0° parallel of latitude is designated the equator, the fundamental plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres. The "longitude" of a point on the Earth 's surface is the angle east or west from a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles. The meridian of the British Royal Observatory in Greenwich, in south-east London, England, is the international Prime Meridian although some organizations—such as the French Institut Géographique National—continue to use other meridians for internal purposes. The Prime Meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order