An overview of Titan’s atmosphere.
Titan, the second largest moon of the Solar system was nothing more than a regular moon until Gerard Kuiper had a closer look at Titan’s spectral lines. When Kuiper discovered the presence of methane around Titan, he proved the existence of an atmosphere around Titan. Since Voyager’s flyby of Titan in the 1980s, researchers are finally able to see and learn more about Titan’s atmosphere and Cassini’s flybys give us an incredible amount of data about Titan. We live in a very interesting time for Titan research, and new research gives us more and more information on this moon with an early Earth-like atmosphere. Learning more about the formation and ...view middle of the document...
Compared to the largest Earth-based telescopes of today, which have apertures of over 30 meters, we would not think that Huygens’ telescope would be of any use.
However, it was with this very small telescope that Huygens did some astonishing discoveries that turned out to be the start of over 350 years of Saturn-watching. In 1655, Huygens spotted an object near Saturn and thought this was a moon. He kept watching the object until in march 1656, when he was certain of his findings and published a pamphlet named “Saturno luna sua circunducitur diebus sexdecim horis quatuor”. In this pamphlet, he did not name the moon he found, but named it Luna Saturni. He kept watching Saturn, and a few years later, he found the rings around Saturn. When Cassini discovered even more satellites of Saturn, a named had to be chosen for these moons.
Eventually, William Herschel’s son, John Herschel, came up with the name Titan for Huygens’ moon. Titan is the 2nd largest moon in the Solar System. Only Ganymede’s diameter is slightly larger than the 5150 km diameter of Titan. Titan’s density is 1.88g/cm3, indicating a composition that is half water ice and half rocky material.
During the period Huygens observed Titan, he noticed that it took the moon 16 days and 4 hours to orbit Saturn. More accurate measurement show that he was only 6 hours away from the actual 15 days and 22 hours orbital period. Titan is tidally locked to Saturn, so the same side of Titan is always facing Saturn. Titan’s mass is almost 96% of the mass of the Saturn Moon system and is therefore very interesting to investigate.
Titan was however never considered much more than a large moon until 1907. In this year, Jose Comas Sola claimed to have seen an atmosphere around Titan. Yet the evidence was not inconclusive. Even though Comas Sola could have been correct, it is not clear whether his observation was actually an atmosphere. “Titan. On the 13th of August 1907, with a clear image and using a magnification of 750, I observed Titan with very darkened edges (somewhat similar to those one observes on the disk of Neptune), while on the central part, much brighter, one sees two round, whiter patches, which give the appearance of a blurred double star. We may suppose, reasonably, that the darkening of the edges demonstrates the existence of a strongly absorbing atmosphere around Titan.”
He seems to be very self-assured about his discovery. Yet there are some problems with this observation. For example, he claimed to see two white patches, where he should have seen only one. Whether or not Comas Sola actually spotted the atmosphere will remain shrouded in mystery, yet it was a great motivation for fellow astronomers, including Gerard Kuiper, to have a closer look at this odd moon. And it was Kuiper who made a remarkable discovery in 1944.
In the beginning of 1944, Kuiper went to McDonald Observatory to investigate the 10 largest satellites. Kuiper chose to use...