**(April 14, 1629 – July 8, 1695)**

An outstanding 17th century researcher, Christiaan Huygens explored mathematics, physics, and philosophy. He corresponded with Pierre de Fermat, Blaise Pascal, and René Descartes. He also taught a young Gottfried von Leibniz maths. After studying Galileo’s works, Huygens built the first pendulum clock. The accuracy of this invention ensured that it remained in vogue for almost three centuries. (From the 1650s until the 1930s when quartz took over, pendulum clocks were the most accurate man-made timepieces). He is as well credited with developing balance spring watch independently of Robert Hooke. Concerning optics, Huygens presented his Wave Theory of Light to an erudite forum at the Paris Science Academy, who appreciated it. His skills as a lens-maker enabled him to exchange ideas with Baruch Spinoza and Antonie van Leeuwenhoek. With the telescope he built, he was able to study Mars’ peripheries before focusing on Saturn, its rings and its largest moon: Titan. His contributions to mathematics were mostly in Geometry, Algebra, Statistics and Applied Mathematics. These included research on the motions of objects, their impacts upon collisions, as well as on gravity. In the process, he became the first European known to have formulated math equation while expressing physics law. Huygens was not avid publisher of works; yet, he published the first European book on Probability Theory: having learnt the theme from Fermat and Pascal. His other essays pertained to astronomy and optics. Dedicated to him are: the 467-kilometer-wide *Huygens* Martian crater, 5.5-kilometer-high* Mons Huygens* lunar mountain, and *2801 Huygens* asteroid.

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