geographic coordinate system — English

A reference system by means of which the exact location of any point or object on the Earth’s surface can be described accurately. Since the Earth is not a flat plane, but a spherical globe, a Cartesian grid could not be used (see “Cartesian coordinates”). Consequently geographers had to develop a similar system of reference, but one that would work on a globe. A grid works perfectly to describe location since each point’s position on the grid is described by two unique coordinates. Hence geographers developed a grid that would work on a sphere. The geographical coordination system consists of an imaginary network, or grid, of two sets of straight lines. One set runs in a north-south-north direction around the globe, and the other in an east-west-east direction. The north-south lines are called lines of longitude (or meridians), and the east-west lines are the lines of latitude (or the parallels). The prime meridian, or Greenwich Meridian (because it runs through Greenwich in England) line is the 0° meridian dividing the Earth into an eastern and a western hemisphere. The main parallel or 0° line of latitude is the equator which divides the Earth into a northern and a southern hemisphere. The north pole and the south pole are respectively the 90°N and the 90°S latitudes and they are not lines, but points. When the absolute location (see “location”) of a place (point) is described, the latitudinal location coordinate is given first and secondly the longitudinal location coordinate, for instance 25°S32°E, or 18°N72°W (see “absolute location” under “location”.) This is commonly – but unofficially – referred to as the Lat-Lo rule. One exception to this rule is the the large scale maps of the British Ordinance Survey where longitude is given first and latitude is given secondly. On these maps lines of longitude are called “eastings” and lines of latitude are called “northings”.

Afrikaans Sesotho sa Leboa isiZulu

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