Titan is a veiled, frigid moon-world, enshrouded beneath a thick orange hydrocarbon fog, as it circles its ringed-gas-giant parent-planet Saturn in the outer Solar System–far from the golden welcoming warmth of our Sun. Titan is a frozen world, like its icy sister-moons that orbit the gaseous, giant denizens of our Solar System’s outer limits: Jupiter, Saturn, Uranus, and Neptune. Almost as big as Mars, Titan is both the largest moon of Saturn, as well as the second-largest moon in our Sun’s family–after Ganymede of Jupiter–and it certainly would have been classified as a planet if it orbited the Sun instead of Saturn. In October 2017, a team of astronomers with NASA’s Cassini mission announced that they found evidence of a bizarre, toxic hybrid cloud looming high above Titan’s south pole. This recent discovery is a new demonstration of the complex chemistry taking place in Titan’s alien, thick, orange atmosphere–in this case, cloud formation in the hydrocarbon-tormented moon’s stratosphere–and part of a group of processes that ultimately helps deliver a strange stew composed of diverse organic molecules to Titan’s odd surface.
Although this floating, wispy, and poisonous cloud is invisible to the human eye, it was successfully discovered at infrared wavelengths by the Composite Infrared Spectrometer (CIRS), aboard the Cassini spacecraft. The cloud haunts the sky of its oddball moon at an altitude of approximately 100 to 130 miles, high above the methane rain clouds that pelt Titan with large, heavy, and lazy drops of a drenching liquid hydrocarbon downpour. The toxic cloud lurks in Titan’s troposphere–the lowest region of its atmosphere–and it covers a large expanse near its south pole, from about 75 to 85 degrees south latitude.
“This cloud represents a new chemical formula of ice in Titan’s atmosphere. What’s interesting is that this cloud’s ice is made of two molecules that condensed together out of a rich mixture of gases at the south pole,” explained Dr. Carrie Anderson in an October 18, 2017 NASA Press Release. Dr. Anderson is of NASA’s Goddard Space Flight Center (GSFC) in Greenbelt, Maryland.
Earlier data obtained from CIRS helped identify the presence of hydrogen cyanide ice in clouds hovering over Titan’s south pole, in addition to other poisonous chemicals in the dense, orange, smoggy blanket that characterizes the distant moon’s exotic atmosphere.