For thousands of years, humans found their way by looking to the sky. Sailors used the constellations, sun, and moon to navigate to distant shores. Today, all that's needed is a device called a GPS receiver. GPS stands for Global Positioning System, and it lets us know where we are and where we are going anywhere on Earth. We still need objects in the sky to know where we are and how we get to other places, but now we use satellites instead of stars. Over 30 GPS navigation satellites are orbiting at an altitude of 12,552 miles (20,200 km) to help us find our way.

Source: Ocean Service