Scientists analyzing data from NASA's Cassini mission have discovered that a giant, toxic cloud is hovering over the south pole of Saturn's largest moon, Titan, after the atmosphere there cooled dramatically.
The scientists found that this giant polar vortex contains frozen particles of the toxic compound hydrogen cyanide, or HCN.
"The discovery suggests that the atmosphere of Titan's southern hemisphere is cooling much faster than we expected," said Remco de Kok of Leiden Observatory and SRON Netherlands Institute for Space Research, lead author of the study published today in the journal Nature.
Titan is the only moon in the solar system that is cloaked in a dense atmosphere. Like our home planet, Earth, Titan experiences seasons. As it makes its 29-year orbit around the sun along with Saturn, each season lasts about seven Earth years. The most recent seasonal switch occurred in 2009, when winter gave way to spring in the northern hemisphere, and summer transitioned to autumn in the southern hemisphere.