<P> Circular Earth geosynchronous orbits have a radius of 42,164 km (26,199 mi). All Earth geosynchronous orbits, whether circular or elliptical, have the same semi-major axis . In fact, orbits with the same period always share the same semi-major axis: </P> <Dl> <Dd> a = μ (P 2 π) 2 3 (\ displaystyle a = (\ sqrt ((3)) (\ mu \ left ((\ frac (P) (2 \ pi)) \ right) ^ (2)))) </Dd> </Dl> <Dd> a = μ (P 2 π) 2 3 (\ displaystyle a = (\ sqrt ((3)) (\ mu \ left ((\ frac (P) (2 \ pi)) \ right) ^ (2)))) </Dd> <P> where a is the semi-major axis, P is the orbital period, and μ is the geocentric gravitational constant, equal to 398,600.4418 km / s . </P>

A satellite is said to be in a geosynchronous orbit if it rotates around the earth