Christiaan Huygens.

Christiaan Huygens (pronounced "HOY-gehnz") was born in The Hague in 1629. His father was a very influential and important man who was friends with the philosopher René Descartes. Huygens did not have formal schooling in his early years, but instead studied at home. From the age of fifteen, he read the works of Descartes, which was to have a profound impact on his later views of science. At the age of sixteen, Huygens was sent to the University of Leiden to study law. In 1647, he transferred to the new University of Breda, which his father directed. Huygens never married, and he devoted his entire life to the advancement of mathematics and the sciences. In 1654, he published a paper on a new way to determine the area of circles accurately. In 1655, Huygens worked with his brother to develop a better way of grinding lenses. Together, they built his first telescope, with which he studied Saturn. That same year, Huygens discovered Saturn's largest moon, Titan. He also was able to see that Saturn's strange appearance was attributable to a disk around the planet in the same plane as Titan's orbit. Huygens published his discovery of Saturn's moon in 1656. For fear of ridicule, however, he did not wish to publish his finding of its rings without further study. In order to prove that he saw the rings first, in case someone else reported them in the meantime, he encoded the discovery in an anagram in his paper about Saturn's moon. In a stroke of genius, he realized that Saturn's rings could not be solid but were likely composed of individual particles. Huygens was also one of the first persons to measure the rotational period of the planet Mars by timing the passage of surface markings across the face of the planet. He also used a micrometer of his own invention to measure the angular sizes of the planets. INSET: Christiaan Huygens.