Space geodesy is

geodesy Geodesy or geodetics is the science of measuring and representing the Figure of the Earth, geometry, Gravity of Earth, gravity, and Earth's rotation, spatial orientation of the Earth in Relative change, temporally varying Three-dimensional spac ...

by means of sources external to Earth, mainly artificial satellites (in satellite geodesy) but also

quasars A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...

(in very-long-baseline interferometry, VLBI), visible stars (in stellar triangulation), and the retroreflectors on the Moon (in lunar laser ranging, LLR).

See also