📘 Definition
Mean motion is the average angular velocity of a satellite, expressed in revolutions per day in TLE format. The ISS has a mean motion of approximately 15.5, meaning it orbits Earth about 15.5 times per day (roughly every 93 minutes). A GEO satellite has a mean motion of approximately 1.0 (one orbit per day). Mean motion can be converted to orbital period and semi-major axis, making it a compact way to encode orbital size.