A
geographic coordinate system is a
coordinate systemIn geometry, a coordinate system is a system which uses one or more numbers, or coordinates, to uniquely determine the position of a point or other geometric element. The order of the coordinates is significant and they are sometimes identified by their position in an ordered tuple and sometimes by...
that enables every location on the Earth to be specified by a set of numbers. The coordinates are often chosen such that one of the numbers represent
vertical positionAltitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
, and two
or three nvector is a three parameter nonsingular horizontal position representation wellsuited for replacing latitude and longitude in mathematical calculations and computer algorithms. Geometrically, it is a unit vector that is normal to the reference ellipsoid. The vector is decomposed in an Earth...
of the numbers represent
horizontal positionA position representation is the parameters used to express a position relative to a reference. Representing position in three dimensions is often done by a Euclidean vector. However, when representing position relative to the Earth it is often more convenient to represent vertical position as...
. A common choice of coordinates is
latitudeIn geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
,
longitudeLongitude is a geographic coordinate that specifies the eastwest position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
and
elevationThe elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
.
Geographic latitude and longitude
The geographic
latitudeIn geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
(abbreviation: Lat., φ, or phi) of a point on the Earth's surface is the angle between the equatorial plane and a line that passes through that point and is
normalA surface normal, or simply normal, to a flat surface is a vector that is perpendicular to that surface. A normal to a nonflat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to a...
to the surface of a
reference ellipsoidIn geodesy, a reference ellipsoid is a mathematicallydefined surface that approximates the geoid, the truer figure of the Earth, or other planetary body....
which approximates the
shape of the EarthThe expression figure of the Earth has various meanings in geodesy according to the way it is used and the precision with which the Earth's size and shape is to be defined. The actual topographic surface is most apparent with its variety of land forms and water areas. This is, in fact, the surface...
.
[The surface of the Earth is closer to an ellipsoid]An Earth ellipsoid is a mathematical figure approximating the shape of the Earth, used as a reference frame for computations in geodesy, astronomy and the geosciences...
than to a sphere, as its equatorial diameter is larger than its northsouth diameter. 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.
[The greatest distance between an ellipsoid normal and the center of the Earth is 21.9 km at a latitude of 45°, using Earth radius#Radius at a given geodetic latitude and Latitude#Comparison of selected types: ] Lines joining points of the same latitude trace circles on the surface of the Earth called
parallelsA circle of latitude, on the Earth, is an imaginary eastwest circle connecting all locations that share a given latitude...
, as they are parallel to the equator and to each other. The
north poleThe North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
is 90° N; the
south poleThe South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
is 90° S. The 0° parallel of latitude is designated the
equatorAn equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
, the
fundamental planeThe fundamental plane in a spherical coordinate system is a plane which divides the sphere into two hemispheres. The latitude of a point is then the angle between the fundamental plane and the line joining the point to the centre of the sphere....
of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres.
The
LongitudeLongitude is a geographic coordinate that specifies the eastwest position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
(abbreviation: Long., λ, or lambda) of a point on the Earth's surface is the angle east or west from a reference
meridianA meridian is an imaginary line on the Earth's surface from the North Pole to the South Pole that connects all locations along it with a given longitude. The position of a point along the meridian is given by its latitude. Each meridian is perpendicular to all circles of latitude...
to another meridian that passes through that point. All meridians are halves of great
ellipseIn geometry, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. Circles are special cases of ellipses, obtained when the cutting plane is orthogonal to the cone's axis...
s (often improperly called
great circleA great circle, also known as a Riemannian circle, of a sphere is the intersection of the sphere and a plane which passes through the center point of the sphere, as opposed to a general circle of a sphere where the plane is not required to pass through the center...
s), which converge at the north and south poles.
A line passing near the
Royal Observatory, GreenwichThe Royal Observatory, Greenwich , in London, England played a major role in the history of astronomy and navigation, and is best known as the location of the prime meridian...
(near London in the
UKThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
) has been chosen as the international zerolongitude reference line, the
Prime MeridianThe Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
. Places to the east are in the eastern hemisphere, and places to the west are in the western hemisphere. The
antipodalIn geography, the antipodes of any place on Earth is the point on the Earth's surface which is diametrically opposite to it. Two points that are antipodal to one another are connected by a straight line running through the centre of the Earth....
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
International Meridian ConferenceThe International Meridian Conference was a conference held in October 1884 in Washington, D.C., in the United States to determine the Prime Meridian of the world. The conference was held at the request of U.S. President Chester A...
and twentyfive nations attended. Twentytwo of them agreed to adopt the location of Greenwich as the zeroreference line. The
Dominican RepublicThe Dominican Republic is a nation on the island of La Hispaniola, part of the Greater Antilles archipelago in the Caribbean region. The western third of the island is occupied by the nation of Haiti, making Hispaniola one of two Caribbean islands that are shared by two countries...
voted against the adoption of that motion, while
FranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semipresidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
and
BrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
abstained. To date, there exist organizations around the world which continue to use historical prime meridians which existed before the acceptance of Greenwich became commonplace.
[The French Institut Géographique National (IGN) maps still use longitude from a meridian passing through Paris, along with longitude from Greenwich.]
The combination of these two components specifies the position of any location on the planet, but does not consider
altitudeAltitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
nor depth.
This latitude/longitude "webbing" is known as the
conjugate graticule.
In defining an
ellipseIn geometry, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. Circles are special cases of ellipses, obtained when the cutting plane is orthogonal to the cone's axis...
, the short (vertical) diameter is known as the
conjugate diameter, and the long (horizontal) diameter—perpendicular, or "transverse", to the conjugate—is the
transverse diameter. With a sphere or ellipsoid, the conjugate diameter is known as the
polar axisIn geometry, the semiminor axis is a line segment associated with most conic sections . One end of the segment is the center of the conic section, and it is at right angles with the semimajor axis...
and the transverse as the
equatorial axisThe major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape...
. The graticule
perspectivePerspective in the graphic arts, such as drawing, is an approximate representation, on a flat surface , of an image as it is seen by the eye...
is based on this designation: As the longitudinal rings — geographically defined, all great circles — converge at the poles, it is the poles that the conjugate graticule is defined. If the polar vertex is "pulled down" 90°, so that the vertex is on the equator, or transverse diameter, then it becomes the
transverse graticule, upon which all
spherical trigonometrySpherical trigonometry is a branch of spherical geometry which deals with polygons on the sphere and the relationships between the sides and the angles...
is ultimately based (if the longitudinal vertex is between the poles and equator, then it is considered an
oblique graticule).
Latitude and longitude in practice
Say you set up your Wild T4 next to the water tank north of the airport at Hilo, Hawaii, intending to determine its latitude and longitude by the stars. NGS predicts you will find the tank to be at 19.7323 deg North, 155.0412 deg West.
You cross the island and set the T4 next to the Keahole Point lighthouse; NGS estimates that by the stars the lighthouse will turn out to be 19.7244 N 156.0787 W. Calculating the distance from the water tank to the lighthouse using those latlons we get about 108.8 km, but if we measure the actual distance it turns out to be 105.5 km. What went wrong?
Hawaii is an extreme case of a problem that exists everywhere: when trying to measure latitude and longitude by the stars we can only orient our measuring device by gravity. We'd like the T4's axis to point to the center of the Earth, but the T4's level vials don't know where that is — all they know is the direction of gravity, which is much affected by that 4000meter mountain 50 km away. So when we measure the latlons for two points the relationship between those two points can be distorted, which renders their latlons fairly useless for most people. When we measure the latlons of two points we want to be able to use those latlons to calculate the distance and direction from one to the other; we want to be able to draw a scale map and plot points on it by their latlons, and the distance between any pair of points on the map is supposed to closely match the actual distance we would measure on the ground.
So we need a different plan — a different definition of latitude and longitude. What they did in Hawaii circa 1930 was call the marker "Oahu West Base" 21 deg 18 min 13.889 sec North, 157 deg 50 min 55.796 West, and define the latlon of every other point by its distance and direction from there. NGS now says that in 1993 that point was 211802.54891 N 1575045.90280 W in the present NAD83 system. Was the old latlon off by 300+ meters? Well, yes, but the relationships between points in the islands were much more accurate than that. C&GS triangulated from island to island, calculating each successive point's latlon by its distance and direction from the previous points in the chain. Eventually they deemed the Hilo water tank to be at 194354.526 N 1550326.463 W, which would make it 339191.7 meters from Oahu West Base on the Clarke 1866 spheroid. NGS now figures those two points are 339192.8 meters apart.
Similarly in North America. If in 1980 you had asked NGS for the latlons for the
Empire State Building and a certain
water tank in Anchorage, the NAD27 latlons they would have given you would be different from the current ones, but the distance you would have calculated then is 8.2 meters different from now. A transcontinental triangulation cannot do better than that.
UTM and UPS systems
The Universal Transverse Mercator (UTM) and Universal Polar Stereographic (UPS) coordinate systems both use a metricbased cartesian grid laid out on a conformally projected surface to locate positions on the surface of the Earth. The UTM system is not a single map projection but a series of map projections, one for each of sixty 6degree bands of longitude. The UPS system is used for the polar regions, which are not covered by the UTM system.
Stereographic coordinate system
During medieval times, the stereographic coordinate system was used for navigation purposes. The stereographic coordinate system was superseded by the latitudelongitude system.
Although no longer used in navigations, the stereographic coordinate system is still used in modern times to describe crystallographic orientations in the fields of
crystallographyCrystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
,
mineralogyMineralogy is the study of chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.History:Early writing...
and materials science.
Geodetic height
To completely specify a location of a topographical feature on, in, or above the Earth, one has to also specify the vertical distance from the centre of the Earth, or from the surface of the Earth. Because of the ambiguity of "surface" and "vertical", it is more commonly expressed relative to a precisely defined vertical datum which holds fixed some known point. Each country has defined its own datum. For example, in the
United KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
the reference point is
NewlynNewlyn is a town and fishing port in southwest Cornwall, England, United Kingdom.Newlyn forms a conurbation with the neighbouring town of Penzance and is part of Penzance civil parish...
, while in Canada, Mexico and the United States, the point is near Rimouski,
QuebecQuebec or is a province in eastcentral Canada. It is the only Canadian province with a predominantly Frenchspeaking population and the only one whose sole official language is French at the provincial level....
,
CanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. The distance to Earth's centre can be used both for very deep positions and for positions in space.
Cartesian coordinates
Every point that is expressed in ellipsoidal coordinates can be expressed as an (Cartesian) coordinate. Cartesian coordinates simplify many mathematical calculations. The origin is usually the center of mass of the earth, a point close to the Earth's
center of figureThe expression figure of the Earth has various meanings in geodesy according to the way it is used and the precision with which the Earth's size and shape is to be defined. The actual topographic surface is most apparent with its variety of land forms and water areas. This is, in fact, the surface...
.
With the origin at the center of the ellipsoid, the conventional setup is the expected righthand:
Zaxis along the axis of the ellipsoid, positive northward
X and Yaxis in the plane of the equator, Xaxis positive toward 0 degrees longitude and Yaxis positive toward 90 degrees east longitude
An example is the
NGS data for a brass disk near Donner Summit, in California. Given the dimensions of the ellipsoid, the conversion from lat/lon/heightaboveellipsoid coordinates to XYZ is straightforward—calculate the XYZ for the given latlon on the surface of the ellipsoid and add the XYZ vector that is perpendicular to the ellipsoid there and has length equal to the point's height above the ellipsoid. The reverse conversion is harder: given XYZ we can immediately get longitude, but no closed formula for latitude and height exists. However, using Bowring's formula in 1976
Survey Review the first iteration gives latitude correct within
degree as long as the point is within 10000 meters above or 5000 meters below the ellipsoid.
Shape of the Earth
The Earth is not a sphere, but an irregular shape approximating a
biaxial ellipsoidAn Earth ellipsoid is a mathematical figure approximating the shape of the Earth, used as a reference frame for computations in geodesy, astronomy and the geosciences...
. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0.3% larger than the radius measured through the poles. The shorter axis approximately coincides with axis of rotation. Mapmakers choose the true ellipsoid that best fits their need for the area they are mapping. They then choose the most appropriate mapping of the spherical coordinate system onto that ellipsoid. In the United Kingdom there are three common latitude, longitude, height systems in use. The system used by GPS,
WGS84The World Geodetic System is a standard for use in cartography, geodesy, and navigation. It comprises a standard coordinate frame for the Earth, a standard spheroidal reference surface for raw altitude data, and a gravitational equipotential surface that defines the nominal sea level.The latest...
, differs at Greenwich from the one used on published maps OSGB36 by approximately 112m. The military system
ED50ED 50 is a geodetic datum which was defined after World War II for the international connection of geodetic networks....
, used by
NATO, differs by about 120m to 180m.
Though early navigators thought of the sea as a flat surface that could be used as a vertical datum, this is far from reality. The Earth has a series of layers of equal
potential energyIn physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
within its
gravitational fieldThe gravitational field is a model used in physics to explain the existence of gravity. In its original concept, gravity was a force between point masses...
. Height is a measurement at right angles to this surface, roughly toward the centre of the Earth, but local variations make the equipotential layers irregular (though roughly ellipsoidal). The choice of which layer to use for defining height is arbitrary. The reference height we have chosen is the one closest to the average height of the world's oceans. This is called the
geoidThe geoid is that equipotential surface which would coincide exactly with the mean ocean surface of the Earth, if the oceans were in equilibrium, at rest , and extended through the continents . According to C.F...
.
The Earth is not static as points move relative to each other due to continental plate motion, subsidence, and diurnal movement caused by the
MoonThe Moon is Earth's only known natural satellite,There are a number of nearEarth asteroids including 3753 Cruithne that are coorbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasisatellites and not true moons. For more...
and the
tideTides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s. The daily movement can be as much as a metre. Continental movement can be up to a year, or in a century. A weather system highpressure area can cause a sinking of .
ScandinaviaScandinavia is a cultural, historical and ethnolinguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethnocultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
is rising by a year as a result of the melting of the ice sheets of the last
ice ageAn ice age or, more precisely, glacial age, is a generic geological period of longterm reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
, but neighbouring
ScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
is rising by only . These changes are insignificant if a local datum is used, but are significant if the global GPS datum is used.
Expressing latitude and longitude as linear units
On the GRS80 or WGS84 spheroid at
sea levelMean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
at the equator, one latitudinal second measures
30.715 metreThe metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one tenmillionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...
s, one latitudinal minute is
1843 metres and one latitudinal degree is
110.6 kilometres. The circles of longitude, meridians, meet at the geographical poles, with the westeast width of a second naturally decreasing as latitude increases. On the
equatorAn equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
at sea level, one longitudinal second measures
30.92 metres, a longitudinal minute is
1855 metres and a longitudinal degree is
111.3 kilometres. At 30° a longitudinal second is
26.76 metres, at Greenwich (51° 28' 38" N)
19.22 metres, and at 60° it is
15.42 metres.
On the WGS84 spheroid, the length in meters of a degree of latitude at latitude φ (that is, the distance along a northsouth line from latitude (φ  0.5) degrees to (φ + 0.5) degrees) is about
111132.954  559.822(cos 2φ) + 1.175(cos 4φ)
(Those coefficients can be improved, but as they stand the distance they give is correct within a centimeter.)
To estimate the length of a longitudinal degree at latitude
we can assume a spherical Earth (to get the width per minute and second, divide by 60 and 3600, respectively):




where Earth's average meridional radius
is . Since the Earth isn't spherical that result can be off by several tenths of a percent; a better approximation of a longitudinal degree at latitude
is




where Earth's equatorial radius
equals
6,378,137 m and
; for the GRS80 and WGS84 spheroids, b/a calculates to be 0.99664719. (
is known as the parametric or reduced latitude). Aside from rounding, this is the exact distance along a parallel of latitude; getting the distance along the shortest route will be more work, but those two distances are always within 0.6 meter of each other if the two points are one degree of longitude apart.
Longitudinal length equivalents at selected latitudes
Latitude 
Town 
Degree 
Minute 
Second 
±0.0001° 
60° 
Saint Petersburg Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...

55.65 km 
0.927 km 
15.42 m 
5.56 m 
51° 28' 38" N 
GreenwichGreenwich is a district of south London, England, located in the London Borough of Greenwich.Greenwich is best known for its maritime history and for giving its name to the Greenwich Meridian and Greenwich Mean Time...

69.29 km 
1.155 km 
19.24 m 
6.93 m 
45° 
BordeauxBordeaux is a port city on the Garonne River in the Gironde department in southwestern France.The BordeauxArcachonLibourne metropolitan area, has a population of 1,010,000 and constitutes the sixthlargest urban area in France. It is the capital of the Aquitaine region, as well as the prefecture...

78.7 km 
1.31 km 
21.86 m 
7.87 m 
30° 
New Orleans 
96.39 km 
1.61 km 
26.77 m 
9.63 m 
0° 
QuitoSan Francisco de Quito, most often called Quito , is the capital city of Ecuador in northwestern South America. It is located in northcentral Ecuador in the Guayllabamba river basin, on the eastern slopes of Pichincha, an active stratovolcano in the Andes mountains...

111.3 km 
1.855 km 
30.92 m 
11.13 m 
Datums often encountered
Latitude and longitude values can be based on different
geodetic systemGeodetic systems or geodetic data are used in geodesy, navigation, surveying by cartographers and satellite navigation systems to translate positions indicated on their products to their real position on earth....
s or datums, the most common being
WGS 84The World Geodetic System is a standard for use in cartography, geodesy, and navigation. It comprises a standard coordinate frame for the Earth, a standard spheroidal reference surface for raw altitude data, and a gravitational equipotential surface that defines the nominal sea level.The latest...
, a global datum used by all GPS equipment.
[WGS 84 is the default datum used in most GPS equipment, but other datums can be selected.] Other datums are significant because they were chosen by a national cartographical organisation as the best method for representing their region, and these are the datums used on printed maps. The latitude and longitude on a map may not be the same as on a GPS receiver. Coordinates from the mapping system can sometimes be roughly changed into another datum using a simple
translationTranslation is the communication of the meaning of a sourcelanguage text by means of an equivalent targetlanguage text. Whereas interpreting undoubtedly antedates writing, translation began only after the appearance of written literature; there exist partial translations of the Sumerian Epic of...
. For example, to convert from ETRF89 (GPS) to the Irish Grid add 49 metres to the east, and subtract 23.4 metres from the north. More generally one datum is changed into any other datum using a process called
Helmert transformationThe Helmert transformation is a transformation method within a threedimensional space...
s. This involves converting the spherical coordinates into Cartesian coordinates and applying a seven parameter transformation (translation, threedimensional
rotationA rotation is a circular movement of an object around a center of rotation. A threedimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...
), and converting back.
In popular GIS software, data projected in latitude/longitude is often represented as a 'Geographic Coordinate System'. For example, data in latitude/longitude if the datum is the North American Datum of 1983 is denoted by 'GCS North American 1983'.
Geostationary coordinates
Geostationary satellites (e.g., television satellites) are over the
equatorAn equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
at a specific point on Earth, so their position related to Earth is expressed in
longitudeLongitude is a geographic coordinate that specifies the eastwest position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
degrees only. Their
latitudeIn geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
is always zero, that is, over the equator.
See also
 Automotive navigation system
An automotive navigation system is a satellite navigation system designed for use in automobiles. It typically uses a GPS navigation device to acquire position data to locate the user on a road in the unit's map database. Using the road database, the unit can give directions to other locations...
 Digital Earth Reference Model
The term Digital Earth Reference Model was coined by Tim Foresman in context with a vision for an all encompassing geospatial platform as an abstract for information flow in support of Al Gore’s vision for a Digital Earth...
(DERM)
 Geographic coordinate conversion
Ways of writing coordinates:All of the following are valid and acceptable ways to write geographic coordinates:* 40:26:46N,79:56:55W* 40:26:46.302N 79:56:55.903W* 40°26′47″N 79°58′36″W* 40d 26′ 47″ N 79d 58′ 36″ W* 40.446195N 79.948862W...
 Geocoding
Geocoding is the process of finding associated geographic coordinates from other geographic data, such as street addresses, or zip codes...
 Geodetic system
Geodetic systems or geodetic data are used in geodesy, navigation, surveying by cartographers and satellite navigation systems to translate positions indicated on their products to their real position on earth....
 Geographical distance
Geographical distance is the distance measured along the surface of the earth. The formulae in this article calculate distances between points which are defined by geographical coordinates in terms of latitude and longitude.An abstraction:...
 Geotagging
Geotagging is the process of adding geographical identification metadata to various media such as a geotagged photograph or video, websites, SMS messages, QR Codes or RSS feeds and is a form of geospatial metadata...
 Greatcircle distance
The greatcircle distance or orthodromic distance is the shortest distance between any two points on the surface of a sphere measured along a path on the surface of the sphere . Because spherical geometry is rather different from ordinary Euclidean geometry, the equations for distance take on a...
the shortest distance between any two points on the surface of a sphere.
 Lambert coordinate system
A Lambert conformal conic projection is a conic map projection, which is often used for aeronautical charts. In essence, the projection superimposes a cone over the sphere of the Earth, with two reference parallels secant to the globe and intersecting it. This minimizes distortion from projecting...
 Map projection
A map projection is any method of representing the surface of a sphere or other threedimensional body on a plane. Map projections are necessary for creating maps. All map projections distort the surface in some fashion...
 Tropic of Cancer
The Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith...
 Tropic of Capricorn
The Tropic of Capricorn, or Southern tropic, marks the most southerly latitude on the Earth at which the Sun can be directly overhead. This event occurs at the December solstice, when the southern hemisphere is tilted towards the Sun to its maximum extent.Tropic of Capricorn is one of the five...
External links