Geosynchronous satellite orbits the earth at an altitude of more than 20,000 km .
Between those extremes lies the `` magic '' altitude of 3 miles ( 35,786 km ) at which a satellite 's orbital period matches , or is an integral part of , the period at which the Earth rotates : once every sidereal day ( 23 hours 56 minutes 4 seconds ) .
Geosynchronous satellite