Two levels of abstraction are employed in the definitions of latitude and longitude. In the first step the physical surface is modeled by the geoid, a surface which approximates the mean sea level over the oceans and its … See more

Ellipsoids
In 1687 Isaac Newton published the Philosophiæ Naturalis Principia Mathematica, in which he proved that a rotating self-gravitating fluid body in equilibrium takes the form of an oblate ellipsoid. (This … See more

There are six auxiliary latitudes that have applications to special problems in geodesy, geophysics and the theory of map projections:
• Geocentric latitude
• Parametric (or reduced) latitude See more

Astronomical latitude (Φ) is the angle between the equatorial plane and the true vertical direction at a point on the surface. The true vertical, the direction of a plumb line, … See more

The graticule on the sphere
The graticule is formed by the lines of constant latitude and constant longitude, which are … See more

The length of a degree of latitude depends on the figure of the Earth assumed.
Meridian distance on the sphere
On the sphere the normal passes through the centre and the latitude (ϕ) is therefore equal to the angle subtended at the centre by the meridian arc … See more

The geodetic latitude, or any of the auxiliary latitudes defined on the reference ellipsoid, constitutes with longitude a two-dimensional coordinate system on that ellipsoid. To define … See more