The puzzling appearance of an ice cloud seemingly out of thin air has prompted NASA scientists to suggest that a different process than previously thought — possibly similar to one seen over Earth’s poles — could be forming clouds on Saturn’s moon Titan.
Above, the hazy globe of Titan hangs in front of Saturn and its rings in this natural color view from NASA’s Cassini spacecraft. Image credit: NASA/JPL-Caltech/Space Science Institute
Located in Titan’s stratosphere, the cloud is made of a compound of carbon and nitrogen known as dicyanoacetylene (C4N2), an ingredient in the chemical cocktail that colors the giant moon’s hazy, brownish-orange atmosphere.
Decades ago, the infrared instrument on NASA’s Voyager 1 spacecraft spotted an ice cloud just like this one on Titan. What has puzzled scientists ever since is this: they detected less than 1 percent of the dicyanoacetylene gas needed for the cloud to condense.
“The appearance of this ice cloud goes against everything we know about the way clouds form on Titan,” said Carrie Anderson, a CIRS co-investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study.