Dutch physicist and astronomer who was the first to examine Saturn's rings (1655), pioneered the use of pendulums in clocks (1657), and formulated Huygens' principle.
Dutch physicist and astronomer who in 1655 discovered Saturn's rings and its fourth satellite, using a telescope he constructed with his brother. In 1657 he built the first pendulum clock. Huygens also proposed that light consists of transverse waves that vibrate up and down perpendicular to the direction in which the light travels. This theory, which explained some properties of light better than Newton's theory, was made public in 1690.