How Satellite Navigation Works

On 30 October 2026 India launched NVS-03, a satellite for its NavIC navigation system. This film explains how satellite navigation works: from the Doppler tone of Sputnik and the Transit system, to measuring distance by timing signals at the speed of light, why a receiver needs four satellites, the GPS constellation and its atomic clocks, the relativity correction of 38 microseconds a day, the ionosphere and multipath, how accuracy improved, and the world's other systems, GLONASS, Galileo, BeiDou, QZSS and NavIC.

Clocks in the sky

How a satellite twenty thousand kilometres away knows where you are.

Read the full story as text · อ่านภาษาไทย

This interactive 3D film needs JavaScript. PlanetPast home