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# Geographic coordinate system

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 Title: Geographic coordinate system Author: World Heritage Encyclopedia Language: English Subject: Collection: Publisher: World Heritage Encyclopedia Publication Date:

### Geographic coordinate system

Longitude lines are perpendicular and latitude lines are parallel to the equator.

A geographic coordinate system is a coordinate system that enables every location on the Earth to be specified by a set of numbers or letters. 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.[1]

## Contents

• Geographic latitude and longitude 1
• UTM and UPS systems 2
• Stereographic coordinate system 3
• Geodetic height 4
• Cartesian coordinates 5
• Shape of the Earth 6
• Expressing latitude and longitude as linear units 7
• Datums often encountered 8
• Geostationary coordinates 9
• On other celestial bodies 10
• Notes 12
• References 13

## Geographic latitude and longitude

The "latitude" (abbreviation: Lat., φ, or phi) 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 is normal to the surface of a reference ellipsoid which approximates the shape of the Earth.[n 1] This line passes a few kilometers away from the center of the Earth except at the poles and the equator where it passes through Earth's center.[n 2] 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" (abbreviation: Long., λ, or lambda) 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 (often improperly called great circles), which converge at the north and south poles.

A line, which was intended to pass through the Royal Observatory, Greenwich (a suburb of London, UK), was chosen as the international zero-longitude reference line, the Prime Meridian. Places to the east are in the eastern hemisphere, and places to the west are in the western hemisphere. The antipodal meridian of Greenwich is both 180°W and 180°E. The zero/zero point is located in the Gulf of Guinea about 625 km south of Tema, Ghana.

In 1884 the United States hosted the

• Mathematics Topics-Coordinate Systems
• Geographic coordinates of countries (CIA World Factbook)
• Coordinates conversion tool (batch conversions of Decimal, DM, DMS and UTM)
• FCC coordinates conversion tool (DD to DMS/DMS to DD)
• Coordinate converter, formats: DD, DMS, DM
• Latitude and Longitude