NASA's Cassini spacecraft spotted a monstrous ice cloud in the south pole of Titan, serving proof of winter coming in on Saturn's moon.
The new cloud of frozen compounds in Titan was imaged by Cassini's camera at an altitude of about 186 miles or in the moon's low to middle stratosphere. Given this much more massive cloud system recently detected, the same cloud first witnessed in 2012 appeared to be "just the tip of the iceberg," according to the NASA statement.
"[T]his ice cloud stood out like nothing we've ever seen before. It practically smacked us in the face," reported Carrie Anderson from the Goddard Space Flight Center of NASA in Greenbelt, Maryland.
Cassini has been seeing the fall-to-winter transition at the Saturn moon's south pole - the first time a spacecraft saw a Titan winter setting in. With each Titan season lasting around 7.5 years based on Earth's time, the area will still be wrapped in winter once the Cassini mission wraps up in 2017.
The cloud buildup in the south pole was deemed an indicator that the global circulation of Titan is changing.
Cassini's infrared device, the Composite Infrared Spectrometer (CIS), made the observations of the cloud, which is low-density and similar to earthly fog but probably flat on top.
But unlike Earth's rain cloud, Titan's ice clouds form differently. While the methane clouds form similarly with Earth's clouds, polar clouds form higher in the atmosphere via a different process: atmospheric circulation brings polar gases in the warm hemisphere to pole of the cold hemisphere, where warm aim sinks.
Cloud layering over different altitudes follows various gases condensing at different temperatures. The new cloud, situated in the lower stratosphere were there are colder temperatures, are composed of compounds that comprise hydrogen, carbon, and nitrogen.
Details on the polar ice clouds' size, composition, and altitude assist scientists in understanding the Titan winter - for instance, the imaged ice cloud told them that south pole temperatures must dip to a minimum of -238 degrees Fahrenheit.
For Goddard Center researcher Robert Samuelson, a glimpse of the Titan's early winter stages proved to be very exciting. "Everything we are finding at the south pole tells us that the onset of southern winter is much more severe than the late stages of Titan's northern winter," he shared.
Anderson presented the findings Nov. 11 at the Meeting of the Division of Planetary Sciences of the American Astronomical Society in Maryland.
The Cassini mission, which arrived at Saturn in 2004 during the north pole's mid-winter, has produced a number of outstanding images as it continues to orbit around the famed ringed planet, including the closest-ever pass over Enceladus, an icy moon.
