Christiaan, Titan, and Huygens

 A History of Life Exploration

full article in PLASMA 6 


Climate disruption, racial violence, the COVID-19 pandemic. Our planet is going through turbulent times. As we face these challenges it is easy to forget that we are just one world in a vast universe of possibilities. But we needn’t go too far to find some close planetary relatives. Saturn’s largest moon Titan (a solar neighbor) seems to hold some kind of relation to our own Earth. Not a twin, but a younger sibling. Studies have shown that Titan bears a striking resemblance to an early-stage Earth. One can’t help but wonder, what can we learn from this strange family member? After all, nothing works better than a relative’s tale to gain some perspective. It all starts with a man who shaped much of this world and others as we see them today.

These six infrared images of Saturn’s moon Titan represent some of the clearest, most seamless-looking global views of the icy moon’s surface produced so far. The views were created using 13 years of data acquired by the Visual and Infrared Mapping Spectrometer (VIMS) instrument on board NASA’s Cassini spacecraft. The images are the result of a focused effort to smoothly combine data from the multitude of different observations VIMS made under a wide variety of lighting and viewing conditions over the course of Cassini’s mission.
Image credit: NASA/JPL-Caltech/University of Nantes/University of Arizona


Christiaan Huygens was one of the leading scientists of the 17th century. Born in 1629, Huygens came from a wealthy and well-connected family, who served in the diplomatic service to the House of Orange. Showing great promise from a very early age, he had an extensive early education which included areas spanning music, geography, and history to astronomy, mathematics, and logic. After graduating from the University of Leiden he decided to devote his life to science.

Mathematician, physicist and astronomer, Huygens led a successful and historically renowned career. His curiosity, intellect, and skill in many disciplines propelled him to a life enriched with many scientific discoveries and innovations. Amongst these was his wave theory of light, which was in direct opposition to Isaac Newton’s (his contemporary) own corpuscular theory of light, i.e., that light moves in particles. At the time, the Englishman’s theory was favored but in spite of this disagreement, the two men respected each other greatly and even met later in Christiaan’s life. It took more than a century before investigators gave credence to the Dutch scientist‘s wave theory. Now we know that light travels both as a wave and as a particle. Another one of his major contributions was his work in horology which resulted in the invention of pendulum clocks.

This work was inspired by Galileo Galilei’s pendulum studies and motivated by his pursuit to develop a marine chronometer that could measure longitudes during sea voyages. The pendulum clock proved useless at sea as the wave motion disrupted the pendulum’s mechanics. However, on land, the clock was a huge success. Its high level of accuracy made the popularization of the pendulum clock spread rapidly across Europe, yet Huygens never received monetary gains for his invention. It wasn’t until the 1930’s that its common use was replaced by electric clocks.

This false-color composite was created with images taken during the Cassini spacecraft’s closest flyby of Titan on April 16, 2005. Image credit: NASA/JPL/Space Science Institute

Huygens’ astronomical work was also greatly influenced by Galileo. Using his deep understanding of astronomy and optics, he manufactured (with the help of his brother Constantijn) even better telescopes than those used by Galileo. His improvements were based on the law of refraction which he used to derive the focal distance of lenses. This method helped correct optical aberrations. He further optimized his telescopes by applying a new method of lens grinding and polishing. These major upgrades were instrumental for the astronomical discoveries that followed. Most notably, his state-of-the-art telescope helped unravel the mystery of Saturn’s “three bodied system” that had previously been observed by Galileo. What was first thought to be a strange triad of celestial bodies (described as two small moons on each side of the planet) turned out to be Saturn’s beautiful rings.

As Huygens inadvertently followed in the scientific footsteps of Galileo, he made another major Saturnian discovery. In 1655, as he pointed his telescope at the gas giant with the intention of studying its rings, he unexpectedly discovered Saturn’s largest moon, Titan. Detailed observations on this new and mysterious moon showed a 16 day long orbit around the planet. However, orbit monitoring aside, the technology of the time did not allow for much more characterization of this alien world. Titan was the first observed moon to orbit Saturn and the sixth moon ever to be discovered after our own and Jupiter’s four Galilean moons (Io, Europa, Ganymede, and Callisto).

Christiaan Huygens died in 1695. His scientific legacy shaped our world and our understanding of it, from his theory of light to the invention of pendulum clocks, and so much more! His discoveries even expanded our knowledge of worlds beyond our own. A founding member of the Acadèmie Royale des Sciences by personal invitation of French King Louis XIV, Huygens’ scientific prowess was second only to Newton’s. However, because he preferred to work in solitary contemplation rather than by means of collaboration, his scientific influence was not as extensive as it could have been during his lifetime. But when the work speaks for itself, it transcends eras. Huygens’ scientific legacy lives on to this day

NASA’s Cassini spacecraft looks toward the night side of Saturn’s moon Titan in a view that highlights the extended, hazy nature of the moon’s atmosphere. During its long mission at Saturn, Cassini has frequently observed Titan at viewing angles like this, where the atmosphere is backlit by the Sun, in order to make visible the structure of the hazes. Image credit: NASA/JPL-Caltech/Space Science Institute

full article in PLASMA 6




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