The 1963 launch of Syncom, the world's first geosynchronous communications satellite, began a communications revolution. Objects placed in orbit over the equator can be synchronized with Earth's daily rotation, appearing to stand still to a ground observer, thus the term geostationary. Non-geosynchronous communications satellites before Syncom required huge swiveling ground antennas and expensive tracking computers to stay in contact with them during the brief time they raced overhead. In contrast, a geosynchronous satellite communicates directly and continuously with any ground station in its line of sight, using fixed antennas. No complex tracking antennas are necessary. Synchronous altitude also means that a satellite is in sunlight 99 percent of the time, eliminating the need for an active temperature control system.