Geodesy or geodetics is the science of measuring and representing the geometry, gravity, and spatial orientation of the Earth in temporally varying 3D space. It is called planetary geodesy when studyi
Geoid, an approximation for the shape of the Earth; shown here with vertical exaggeration (10000 vertical scaling factor).
The World Geodetic System is a standard used in cartography, geodesy, and satellite navigation, including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and
Geodesy
…System (GIS) databases. Geodetic GNSS (most commonly GPS) receivers directly produce 3D coordinates in a geocentric coordinate frame. One such frame is WGS84, as well as frames by the International Earth Rotation and Reference Systems Service (IERS). GNSS receivers have almost completely replaced terrestrial…
Handheld GPS receiver at the Royal Observatory, Greenwich, indicating that the Greenwich meridian is 0.089 arcminutes (or 5.34 arcseconds) west of the WGS 84 datum (the IERS Reference Meridian)