Christiaan Huygens, FRS (English pronunciation: /ˈhaɪɡənz/, Dutch: [ˈhœyɣəns]; 14 April 1629 – 8 July 1695) was a prominent Dutch mathematician, astronomer, physicist, horologist, and writer of early science fiction. His work included early telescopic studies elucidating the nature of the rings of Saturn and the discovery of its moon Titan, investigations and inventions related to time keeping and the pendulum clock, and studies of both optics and the centrifugal force.