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, apperaing to stand still to a ground observer, thus the term geostationary. Nongeosynchronous 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.