June 3, 2009

Titan’s clouds move slower than expected

U.S. space agency scientists have discovered cloud formations on Saturn's moon Titan move much like those on Earth, but in a much slower fashion.

Scientists with the National Aeronautics and Space Administration's Cassini mission monitored Titan's atmosphere between July 2004 and December 2007, observing more than 200 clouds. They said they discovered cloud distributions around Titan match global circulation models except for timing -- clouds were still noticeable in the southern hemisphere while fall approached.

Titan's clouds don't move with the seasons exactly as we expected, said Sebastien Rodriguez of the University of Paris. We see lots of clouds during the summer in the southern hemisphere, and this summer weather seems to last into the early fall. It looks like Indian summer on Earth, even if the mechanisms are radically different on Titan from those on Earth.

Researchers said it's possible the sluggishness of temperature changes at the surface and low atmosphere on Titan might be responsible for its unexpected warm and wet, and therefore cloudy, late summer.

More information and infrared images showing Titan's global cloud pattern are available at http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=3532.