However, Nasa has not yet revealed the exact size of the cloud.
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The new cloud was detected by Cassini’s infrared instrument – the Composite Infrared Spectrometre, or CIRS – which obtains profiles of the atmosphere at invisible thermal wavelengths. The cloud has a low density, similar to Earth’s fog but likely flat on top.
Winter comes on Saturn’s moon Titan with a very big ice cloud captured by NASA’s Cassini Spacecraft.
Cassini has been able to witness the transition of fall to winter at the south pole of Titan over the years, and it is the first spacecraft to witness the starting of winter on Titan.
“It practically smacked us in the face”, said Anderson. Cassini s camera spotted this impressive cloud hovering at an altitude of about 186 miles (300 kilometers).
The findings were presented at the annual Meeting of the Division of Planetary Sciences of the American Astronomical Society.
Beneath the orange haze of Saturn’s moon Titan, methane rains from the sky and pools in lakes – and might even burst forth from massive storm squalls like those seen on Earth. However, Titan is the only natural satellite known to have a dense atmosphere.
“From the long slant paths that are available from limb-viewing CIRS far-IR spectra, we have the first definitive detection of the ν6 band of cyanoacetylene (HC3N) ice in Titan’s south polar stratosphere”, she reported.
NASA’s Cassini probe, which has been investigating Saturn and its moons for the last few years, has beamed back some interesting data.
But in fact, the cloud is much larger than scientists originally thought.
The small bright button represents the ice cloud on Titan. 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. At the cold pole, the warm air drops-almost like water draining out of a bathtub-in a process referred to as subsidence.
The falling gases, a combination of smog-like hydrocarbons and nitrogen-bearing chemicals called nitriles, come across colder and colder temperatures as they fall down.
Different gases will condense at different temperatures, resulting in a layering of clouds over a range of altitudes.
Cassini had arrived at Titan in 2004, when the north pole of Saturn moon was just beginning to change from winter to spring. Currently, the north pole is transitioning to spring. Now, winter is coming to the south pole and scientist are preparing to see was that looks like. The build-up of these southern clouds indicates that the direction of Titan’s global circulation is changing.
“Titan’s seasonal changes continue to excite and surprise”, said Scott Edgington, one of the researchers. Using the latest info, astronomers estimate temperatures are as low as -238 Fahrenheit. “It’s more than enough to carve the river channels and fluvial features we see on the surface”, says Rafkin, of the Southwest Research Institute in Boulder, Colo. This growing cloud is detected at the mid-stratosphere, the stable atmospheric region above the troposphere or active weather layer of the body.
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The very strong signature of the south polar cloud supports the idea that the onset of winter is much harsher than the end.
