How Do Global Positioning Systems, or GPS, Work?
Illustration of the 29 GPS satellites orbiting the Earth

The information in this video was accurate as of the original publication date.

Audience: Educators and Students
Grades: K-8
Year: 2005


A NASA expert explains why GPS needs 24 satellites to work. He explains how trilateration works with a two-dimensional model. Then the expert shows how the information from four satellites can identify an exact location on Earth.

How Do Global Positioning Systems, or GPS, Work?
Duration: 4 minutes 15 seconds
> View QuickTime  [14MB]


This video clip is part of the The Case of the Technical Knockout DVD that may be ordered from the Central Operation of Resources for Educators, or CORE  →.

Other video learning clips in this series:
Navigational Uses for Global Positioning Systems, or GPS
Early Navigation, How Was It Done?
Radar, Radio Waves and Light
What Is Electricity?
Experimenting With Electromagnets
Earth's Role as an Electromagnet and the Creation of Auroras
NASA's Research on the Sun
All About Solar Flares
What Are Geomagnetic Storms?