Geographic coordinate system

Map of Earth showing lines of latitude (horizontally) and large version (pdf, 1.8MB)

A geographical coordinate system is a coordinate system. This means that every place can be specified by a set of three numbers, called coordinates.

A full circle can be divided into 360 degrees (or 360°); this was first done by the Babylonians; Ancient Greeks, like Ptolemy later extended the theory.

Today, degrees are divided further. There are minutes, and seconds; 1 minute (or 1') in this context is 1/60 of a degree; 1 second (or 1") is 1/60 of a minute.

The first concept needed is called latitude (Lat, or the Greek symbol "phi", ). For it, the Earth is cut up into 180 circles, from the Equator at 0°. The poles are at 90°, the North Pole is at 90° N(orth), the South Pole is at 90° S(outh). Places with the same latitude are on a circle, around the Earth.

The other concept is called longitude (Long, or the Greek symbol "lambda", ), sometimes referred to as "meridian". The 0° longitude line (or zero meridian) goes through the Royal Observatory in Greenwich. Greenwich is a part of London. Then lines are drawn in a similar way; the opposite (or "antipodal") meridian of Greenwich is considered both 180°W(est), and 180°E(ast).

The third number is the height, altitude, or depth. This is given with respect to some fixed (usually easily calculable point). One of these is called mean sea level.

Other Languages
Alemannisch: Geografische Lage
Bân-lâm-gú: Keng-hūi-tō͘
Basa Banyumasan: Sistem koordinat geografi
беларуская (тарашкевіца)‎: Геаграфічныя каардынаты
客家語/Hak-kâ-ngî: Thi-lî chhô-phêu ne-thúng
한국어: 지리 좌표계
hornjoserbsce: Geografiske koordinaty
Bahasa Indonesia: Sistem koordinat geografi
íslenska: Bauganet jarðar
Lëtzebuergesch: Geographesch Koordinaten
Baso Minangkabau: Sistem koordinat geografis
Mìng-dĕ̤ng-ngṳ̄: Dê-lī cô̤-biĕu hiê-tūng
日本語: 地理座標系
oʻzbekcha/ўзбекча: Geografik koordinatalar
Plattdüütsch: Geograafsche Laag
srpskohrvatski / српскохрватски: Geografske koordinate
татарча/tatarça: Geografik koordinatalar
Türkmençe: Koordinatalar
中文: 经纬度