How do GPS devices pinpoint our exact location on Earth?

GPS devices figure out where you are by talking to satellites that are way up in space.

Imagine you have a friend who lives far away, but they can tell you exactly how far away you are from their house, just by using a special kind of watch. That’s like what satellites do for GPS devices. Each satellite sends out a message saying, “I’m here!” and the GPS device listens.

The GPS device measures how long it takes for each message to reach it. Since messages travel at a super-fast speed, like light, even a tiny difference in time means a big difference in distance. The GPS uses this information from several satellites to find out your exact location on Earth, just like you might use clues from different friends to figure out where you are.

If you only had one friend telling you how far away you were, you’d know you were somewhere on a big circle around them. But if two friends told you the same thing, you’d be at the place where those circles overlap, and that’s your location! GPS uses this idea with multiple satellites to pinpoint exactly where you are.