Play the GPS game!
(Multimedia version)

(Alternative version)

The Global Positioning System (GPS) is a system of 24 satellites that orbit the Earth. The GPS satellites track their own positions using information sent from control stations on Earth. Every few seconds, each satellite broadcasts a signal containing information about its position, along with the exact time.

A GPS receiver is used to determine geographic position on Earth. The receiver collects signals from GPS satellites and, based on the difference between the time a signal was sent and the time it was received, determines its distance from each satellite. The receiver then calculates the intersections of the distances from each satellite to determine its position.

This tool is especially useful to locate archaeological sites that exist far away from any landmarks, especially those out in the deserts. It can also be used to travel at night and know where you are without using the stars.