Satellite positions are specified using a

Coordinate systems can be the familiar

Here are some of the common coordinate systems:

* Geodetic Cartesian (called "Earth-Fixed Greenwich" - EFG - by NASA)

* Inertial (Celestial) Cartesian (called "Earth-Centered Inertial" - ECI - by NASA).

Both of these systems use the center of the earth as the origin, and the axis of the earth as one axis (Z, or G axis. But the inertial system has the other two axes (X, Y) fixed with respect to the stars, while the geodetic system (E, F) keeps them fixed with respect to the surface of the earth.

* Latitude/Longitude/Altitude - a spherical system

* Right Ascension/Declination - another spherical system

* Orbital