The Global Positioning System, or GPS, is a space-based system that helps you find your exact location and tells you the time, almost anywhere on Earth. It's like having a guide in the sky! The United States Space Force owns and operates GPS, but anyone with a GPS receiver can use it for free. You don't even need internet or phone service for it to work.
The U.S. Department of Defense started the GPS project in 1973, and by 1993, a full network of 24 satellites was working. At first, GPS was mainly for the military. However, after a civilian airplane got lost and shot down in 1983, President Ronald Reagan decided to make GPS available for everyone to use.
In the beginning, civilian GPS wasn't quite as accurate because of something called "Selective Availability," which introduced a small error. Thankfully, this deliberate error was turned off by President Bill Clinton in 2000, making GPS much more accurate for everyone. Modern GPS systems continue to improve, offering incredible precision, with some systems pinpointing your location within centimeters.
Your smartphone's GPS, often helped by Wi-Fi signals, can usually get your location within a few meters. The development of GPS was also strongly driven by the Cold War, as it was crucial for the accurate targeting of missiles for national defense. Even Albert Einstein's theories of relativity play a role; GPS satellites have super-accurate atomic clocks that run a tiny bit faster in space, and the system has to account for this difference to give you the correct location. Today, GPS is constantly being updated with new satellites and technology to make it even better and more reliable for all its users worldwide.
