geo-sta-tion-ary \-'sta^--she-,ner-e^-\
:of, relating to, or being an artificial satellite that travels above the equator and at the same speed as the earth rotates so that the satellite seems to remain in the same place
Geostationary (also called geosynchronous) satellites have better time resolution that polar orbiting satellites, but they are restricted to a single location. Geosynchronous satellites all fly at an altitude of 35,910 km which is determined by gravity, the mass of the earth and the requirement that a geosynchronous satellite have a period of one day.