天体力学 tiāntǐlìxué celestial mechanics Origin Definitions Defs Strokes Stroke Words Sentences Sents 天体 天體 tiāntǐ noun celestial body General term for objects in the universe, including stars, planets, satellites, comets, meteors, and cosmic dust力学 力學 lìxué mechanics branch of physics concerned with the motion of objects and the forces acting upon them