How does GPS know exactly where I am?

GPS knows exactly where you are by using special signals from satellites high up in space.

Imagine you have a friend who can tell you how far away you are from them, not just if you're close or far, but exactly how many steps it would take to get there. Now imagine you have four friends, each telling you their distance from you at the same time. With that information, you could figure out where you are on a map.

That’s what GPS does, like having four special friends in space sending messages down to your phone or watch.

Each satellite sends a message with the exact time it was sent. Your phone uses that time and how long it took for the signal to reach it to calculate distance.

It’s kind of like when you throw a ball up in the air, if you know how long it takes to come back, you can guess how high it went. GPS does something similar, but with signals instead of balls.

Using just one satellite is like knowing your distance from one friend, you could be anywhere on a circle around them. With two satellites, it’s like being somewhere on the place where two circles overlap.

But with four satellites, your phone can pinpoint exactly where you are, like finding the only spot where all four circles meet!