Technology
GPS Satellite Timing
Quick fact
Each GPS satellite carries four atomic clocks, accurate to about one nanosecond (billionth of a second). A timing error of just one nanosecond would cause a position error of about 30 centimeters.
Why this is interesting
Your phone knows exactly where you are on Earth—did you know it's all because of extremely precise time signals from satellites orbiting 20,000 km away?