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Titan's South Polar Vortex (True Colors; credits: NASA/JPL-Caltech/Space Science Institute)
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Caption NASA:"This frame (taken by the NASA - Cassini Spacecraft) shows us a South Polar Vortex or, in other words, a swirling Mass of Gas (and, perhaps, even other - heavier - Elements), which is located in the Upper Atmosphere, and approximately over the South Pole, of the Saturnian moon Titan. This Swirling Mass appears to complete one full rotation in about 9 (nine) hours - meaning a much faster period than the moon's 16 (sixteen)-days Rotation Period. The South Pole of Titan (which is about 3200 miles, or 5150 Km, across) is right under the Vortex.
Since the NASA - Cassini Spacecraft arrived in the Saturnian System, in 2004, Titan has shown a visible "Hood", such as an area of denser (when compared to the rest of the moon's Atmosphere) High Altitude Haze, high above the North Pole, but this is the first time that a similar phenomenon is seen above its South Pole. As a matter of fact, it was Northern Winter on Titan at the time of the arrival of the Cassini Spacecraft, and therefore much of its High Northern Latitudes was then in the darkness. But the Hood was high enough to still be illuminated by Sunlight. However, seasons have been changing since Saturn's August 2009 Equinox, which signaled the beginning of Spring in the Northern Hemisphere and the start of Fall (---> Autumn) in the Southern one, both for Saturn and for its very many moons. As a consequence of this season's changing, now the High Southern Latitudes are the ones moving into darkness, and the formation of this Vortex at Titan's South Pole may be related to the incoming Southern Winter and - maybe - the subsequent beginning of what could well be a South Polar Hood.
These new, more detailed images are only possible because of the NASA - Cassini Spacecraft newly inclined orbits, whose re-definition is part of the next phase of the Cassini Solstice Mission. Previously, Cassini was orbiting along the Equatorial Plane of Titan, and so the imaging team's pictures of the Polar Vortex (in the period between late March and mid-May), were taken from over Titan's Equator. At that time, however, the images taken by the Spacecraft only showed a brightening (or yellowing) of the detached Haze Layer located on the Limb (or Edge) of the Visible Disk of Titan, right over its South Polar Regions".
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(Dettagli)
