For thousands of years, humans navigated their way around the earth by the sun and the stars. Today, with all the benefits of modern technology, we still look to the sky for direction. From its first iteration in the military to making driving easier for people all over the world, GPS navigation is a great feat of modern ingenuity. Far beyond the range of the naked eye, there are a couple dozen satellites zooming around above our heads. Whenever your GPS navigator is turned on, it’s constantly receiving radio signals from these satellites in order to figure out its current position on the earth’s surface. The way it does this is called ‘trilateration.’ A GPS navigator needs at least three signals from different satellites to calculate its location and at least four to calculate altitude. This is because each satellite is programmed to send out signals at regular intervals. Your GPS navigator already knows when these signals are supposed to be sent out and where in their orbit each satellite is supposed to be at any given time. Knowing how fast the signals travel, the GPS navigator can use the time difference between the signal being sent and when it was received to calculate how far away it is from that particular satellite. So, with your GPS navigator knowing how far it is from one satellite, there’s a whole circle along which it could possibly be. A second signal from a different satellite narrows it down to two points and a third signal eliminates one of them. At last, you get down to a single point on the earth where you can possibly be. As for the maps and street information you use to get around, all that data is already loaded onto the device and simply gets cross-referenced with your geographical position. This process is extremely precise, though. Since it all relies on radio signals which can be blocked, bounced or otherwise affected by the atmosphere, your GPS navigator can get confused depending on the weather or large structures getting in the way. Luckily, while even an error of the smallest fraction of a second in the timing calculation can cause a difference of many kilometres in the final readout, we are typically in view of more than three satellites at any one time, which your GPS navigator cleverly uses to gauge inaccuracies. All this great technology adds up to you getting where you need to go! We think that makes a GPS navigator a pretty good investment.