A discovery of ‘Titan’ic proportions

Christiaan Huygens, a Dutch astronomer, inventor, physicist and mathematician, discovered Saturn’s largest moon, Titan, on March 25, 1655. Nearly 350 years later, his namesake, the Huygens probe, landed on that moon to learn more about it. A.S.Ganesh gazes at Huygens’ discovery of Titan and other important contributions that he made to science…

Updated - November 10, 2021 12:20 pm IST

Published - March 25, 2018 02:01 pm IST

While the image on the left  shows Saturn’s largest moon Titan, the one on the right  shows Titan with Saturn's rings in the background.

While the image on the left shows Saturn’s largest moon Titan, the one on the right shows Titan with Saturn's rings in the background.

The 20-year journey of the Cassini-Huygens mission, which came to an end in September 2017, has provided us with a trove of data from which we’ll mine vital information in the years to come. An ambitious project that brought together NASA, the European Space Agency and Agenzia Spaziale Italiana (Italy’s space agency) among others, Cassini-Huygens has allowed us to better explore and understand Saturn’s system.

One can’t think of a better way to honour Italian astronomer Giovanni Cassini and Dutch scientist Christiaan Huygens, after whom the mission was named. Let us see how exactly the latter, Huygens, whose name was used for the probe, was involved with Saturn.

Well-connected family

Born in 1629 into an affluent Dutch family, Huygens was exposed to some of the brightest minds of his times right from a very young age. French philosopher and scientist Rene Descartes (of “Cogito, ergo sum” or “I think, therefore I am” fame) was a friend of Huygens’ father and he was impressed with young Huygens’ early efforts at geometry.

Huygens penchant for drawing and mathematics was clear as he learned from private tutors at home and he went on to study mathematics and law at the University of Leiden from 1645.

From maths to telescopes

Following some initial publications pertaining to mathematics, Huygens turned his attention to telescopes in 1654. Along with his brother Constantijn, Huygens started working on the manufacture of telescopes and developed a suitable theory for it.

Using a better method for grinding and polishing the lenses, Huygens was able to optimise his telescopes further and obtain increased clarity from them. Huygens also arrived at wonderful explanations for reflection and refraction and utilised them to derive the focal length of his lenses.

Discovers Titan

It was using one of these telescopes that Huygens discovered Saturn’s largest moon. Huygens turned his attention to Saturn to find the secret behind its elongated appearance, which had been observed using less accurate techniques (even Galileo had observed this earlier, and had drawn it in his notebook – like ears on the planet).

On March 25, 1655, Huygens was able to discover a satellite of Saturn, now known to be its largest. Once spotted, it was easy to observe and Huygens also determined its period of revolution. It was named Titan almost two centuries later by Sir John Herschel, since the name corresponded to something large, powerful and very important.

Suggests rings

With continued observations, Huygens was able to suggest that Saturn’s elongated appearance could well be because it had rings and that further research would be needed to confirm the same. While the scientific community was skeptical about this suggestion for starters, it turned out to be the truth and Saturn was proved to be a ringed planet.

It was these fundamental contributions towards understanding Saturn’s system that led to the choice of Huygens’ name for the probe that was launched in 1997. And when Huygens probe finally landed on Titan in January 2005, nearly 350 years after he had discovered the moon, it continued to do what Huygens had started – provide further insights into Saturn and its system.


Hear, hear! Huygens…

* Huygens is also considered the founder of the wave theory of light. His interest in telescopes gradually spilled over to optics and he spent considerable time studying the mechanics of light. He postulated that light travelled in waves but his theory was rejected by Isaac Newton, who believed in the particle nature of light.

* Even though Huygens was respected by Newton himself, his work on light was overshadowed by that of Newton for over a century. So much so that it was only in the 19th century that Huygens’ contribution in this field was appreciated for its originality and brilliance. We now know that light has wave-particle duality – it exhibits properties of both waves and of particles.

* Huygens was also the inventor of the pendulum clock. As someone interested in measuring time, he discovered that pendulums could be employed to regulate clocks. Further, he was able to bring down the error from about a minute every day to less than ten seconds a day by improving the clock.

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