How does GPS know exactly where I am on Earth?

GPS knows exactly where you are on Earth by using signals from special satellites above us.

Imagine you have a big toy map that shows your whole room. If you can see how far you are from three different corners of the room, you can figure out exactly where you are standing. GPS works like this, but instead of a room, it’s our whole Earth, and instead of corners, there are satellites in space.

Each satellite sends out a signal, like a beep that says, “I’m here!” Your phone or GPS device listens to these beeps from several satellites.

By timing how long the signal takes to reach you, your device can figure out how far it is from each satellite. This is just like when you shout across a room and time how long it takes for someone else to reply, based on that time, you can guess how far apart you are.

Once your phone knows its distance from at least three satellites, it can find exactly where you are on Earth, just like knowing your distance from three corners of the room helps you figure out your spot in it!