noun
Technical term in astronomy and space engineering. Refers to an orbit where a satellite's orbital period matches Earth's rotation, appearing stationary relative to a fixed point on Earth.
通信衛星は対地同期軌道に投入された。
The communications satellite was placed into geosynchronous orbit.
静止軌道 (geostationary orbit) is a special case of 対地同期軌道 with zero inclination and eccentricity, so the satellite appears fixed at one point in the sky.
Compound of 対地 (taichi, 'relative to the earth'), 同期 (dōki, 'synchronization'), and 軌道 (kidō, 'orbit').