At an altitude of 22,300 miles, geosynchronous
satellites take exactly one day to orbit the earth, and therefore appear to hover over one spot above the
equator. Receiving and transmitting antennae on the earth do not need to track such a satellite, are fixed in place and are much less expensive than tracking antennae. They have revolutionized global communications, positioning, navigation and
television broadcasting. The original concept was developed by the
science fiction author
Arthur C. Clarke about
1945.