In optics, he is best known for his wave theory of light, which he described in his Traité de la Lumière (1690). In 1659, Huygens derived geometrically the formula in classical mechanics for the centrifugal force in his work De vi Centrifuga, a decade before Newton. Huygens first identified the correct laws of elastic collision in his work De Motu Corporum ex Percussione, completed in 1656 but published posthumously in 1703. A talented mathematician and physicist, his works contain the first idealization of a physical problem by a set of mathematical parameters, and the first mathematical and mechanistic explanation of an unobservable physical phenomenon. As an engineer and inventor, he improved the design of telescopes and invented the pendulum clock, the most accurate timekeeper for almost 300 years. In physics, Huygens made seminal contributions to optics and mechanics, while as an astronomer he studied the rings of Saturn and discovered its largest moon, Titan.

Christiaan Huygens, Lord of Zeelhem, FRS ( / ˈ h aɪ ɡ ən z/ HY-gənz, US: / ˈ h ɔɪ ɡ ən z/ HOY-gənz, Dutch: ⓘ also spelled Huyghens Latin: Hugenius 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor who is regarded as a key figure in the Scientific Revolution.