In the 1980s, it was discovered that atomic clocks run at different rates in different orbits. Clocks run slowest in low space shuttle orbits and then run faster and faster in higher and higher orbits until, at an orbit of about 1.5 times Earth’s radii, they surpass the rates of sea level clocks. Physicists were able to use the equations of Einstein’s special and general theories relativity to calculate the correct rates for orbiting clocks but these equations were based on unmeasured metaphysical assumptions of relative motion. It is shown here that the same accurate calculations can be made using physical principles of measurements of absolute motion.