"We shall be less apt to admire what this World calls great...when we know that there are a multitude of such Earths inhabited and adorn'd as well as our own." At the time Christiaan Huygens wrote those words, intellectuals in Europe were still arguing over the Copernican and Aristotelian models of the universe. Huygens, unlike many of his colleagues in the 17th century, was convinced that the Copernican view was completely accepted by all astronomers except those who "were a bit slow-witted or under the superstitions imposed by merely human authority."

Christiaan Huygens was a contemporary of Robert Hooke, Anton van Leeuwenhoek, Jan Vermeer, and Isaac Newton. He studied any and all areas in science that interested him. From intensive observations of the microscopic world using a modified and more powerful version of Leeuwenhoek's "viewing glass" to the identification of the rings of Saturn and a confirmation of Hooke's observation of Jupiter's Great Red Spot, from the invention of the pendulum clock which allowed mariners to reasonably measure longitude to an elegant and comprehensive explanation of the wave theory of light; Huygens was perhaps the last great scientist who was truly comfortable in all areas of mathematics and science.

Born in Holland in 1629, he was the only son of Constantijn Huygens. The elder Huygens served as a leading diplomat of the Dutch Republic and was also a poet, composer, musician, and patron of the arts. His father entertained lavishly and invited many distinguished visitors to his home. Surrounded by such luminaries as John Donne, Rene Descartes, and Rembrandt van Rijn, the young and impressionable Huygens became simultaneously adept in languages, art, music, law, science, mathematics, and engineering. His love for learning was vast and unyielding. "The world is my country," he said, "science my religion."

Christiaan Huygens began his real work in 1648. With the help of Baruch Spinoza, who would later become a renowned philosopher, he developed an improved way of grinding lenses and then proceeded to build some of the largest refracting telescopes of the day. In 1656, he discovered the Orion Nebula and Saturn's largest moon, Titan. Within the next decade, he would measure the size of Mars, identify surface features on Mars, and, using these features (Syrtis Major), determine the length of the Martian day. He also predicted that the surface of Venus was covered with clouds. Although Galileo had first identified "strange lobes, like ears, about the planet Saturn," Huygens first recognized that, in fact, Saturn was surrounded by a system of several distinct rings, of which none that actually touched the planet.

In 1672, Huygens was elected the first president of the newly-formed French Academy of Sciences; an especially unique honor as he was not even a French citizen. He would serve in that position until 1690 when he resigned due to his increasingly frail health. Since he had not resided in France for nearly a decade, and had not actually attended a meeting for nearly six years, it seemed an appropriate time to relinquish his office.

During the next eighteen years, the most productive period of his life, Christiaan Huygens would turn his attention from the mysteries of the heavens to more fundamental puzzles. One of the most important and pressing problems for a maritime power like Holland was the determination of longitude. Latitude could be easily determined by the stars; the farther south you travel, the more southern constellations you see. But longitude required precise timekeeping. An accurate clock on board ship would keep track of time in the home port; measurements of the rising and setting of the Sun and stars gave local ship time. The difference between the two times would yield the longitude of the ship. Huygens set out to perfect the pendulum clock, the principles of which had first been discovered by Galileo. Despite unprecedented improvements in accuracy, Huygen's isochronistic pendulum clock never worked properly on board a moving, rolling, rocking boat. Instead, it would take nearly one hundred years before John Harrison would complete the first marine chronometer which could measure time accurate to a loss of just 5 seconds over a period of 80 days.

In 1678, Christiaan Huygens again changed the direction of his work. Using his experience grinding lens twenty years before, he formulated a theory of light which assumed light acted like a wave. Huygens argued that light behaved as if it were a wave propagating through a vacuum, such as an ocean wave moves through the sea. Even though this was opposite the view of many of his contemporaries, including Isaac Newton (who, in 1704, proposed a particle model for light), it could better explain reflection, refraction, and especially diffraction than the often differing prevailing views of the times. In 1801, Thomas Young would show conclusively that light does, in fact, act like a wave by using another property predicted by Huygen's wave model of light; interference. In 1905, Albert Einstein would finally complete the marriage of Huygen's wave model and Newton's particle view of light by explaining a mysterious and nonsensical behavior of light known as the photoelectric effect.

In the 1680's, Christiaan Huygens was considered one of the greatest scientists of the day. He was respected and admired by Newton as "the most elegant mathematician" of their time; quite a compliment from the inventor of the calculus and a mathematician of no small notoriety. But he was also struggling with failing health. He seldom journeyed from his home in Holland, often canceling trips due to some strange "consumptive disease that weakens both the heart and soul." However, he continued his prodigious scientific output by inventing a magic lantern -- an ancestor of the slide projector -- and the gunpowder engine (which would influence the development of the steam engine). He improved the air pump (later used to revolutionize the mining industry), described the fundamental properties of centrifugal and centripetal force, and developed the first mathematical models of probability theory.

In 1690, Huygens wrote his last, great treatise. The Celestial Worlds Discover'd: Conjectures Concerning the Inhabitants, Plants, and Productions of the Worlds in the Planets, was admired by scientists, mathematicians, artists, musicians, and kings. This extraordinary book, the first of its kind, gave credence to the idea that the Universe be populated with "...so many Suns, so many Earths ...And how must our Wonder and Admiration be increased when we consider the prodigious Distance and Multitude of the Stars." It would take nearly 300 years for us to recognize the truth in those words, and those words live on today. Though many of his conjectures were wrong, we are amazed at the inherent truth in Huygen's imagination. He was, perhaps, our first true traveler among the stars, and we are richer for it.

Christiaan Huygens died in his sleep in 1695.

Article courtesy of Michael Sinclair