A strange vortexhas been spied 200 miles above Saturn’s biggest moon, Titan. NASA’s Cassini probe photographed the polar vortex, a huge body of swirling gas – as it moved roughly 200 miles above Titan’s south pole. The vortex was detected during a flyby of Titan on June 27.
Scientists have theorized that this may indicate winter is coming to the moon’s southern reaches.
While Titan takes approximately 16 days to spin once around its axis, the vortex appears to complete a full rotation in nine hours. In a NASA statement, Tony Del Genio, a Cassini team member at the Goddard Institute for Space Studies in New York, said:
“The structure inside the vortex is reminiscent of the open cellular convection that is often seen over Earth’s oceans. But unlike on Earth, where such layers are just above the surface, this one is at very high altitude, maybe a response of Titan’s stratosphere to seasonal cooling as southern winter approaches. But so soon in the game, we’re not sure.”
Cassini entered the Saturn system in 2004, when Titan – which is roughly 50% larger than Earth – had a vortex and a visible layer of dense haze high above its north pole. It remained winter in that part of Titan until Saturn’s August 2009 equinox. That brought about spring in the northern hemisphere, while Saturn’s southern reaches and many of its 62 known moons saw the arrival of fall.
The northern haze on Titan remains, but researchers revealed the circulation in the upper atmosphere has been gradually shifting from the warming north pole to the cooling south. This move seems to be triggering downwellings over Titan’s south pole, along with the formation of high-altitude haze and a vortex.
Cassini’s team on earth will now watch Titan’s south pole closely for further developments; these could lead to a significant breakthrough in our knowledge of Titan’s complex, methane-based weather system. Bob West, Cassini deputy imaging team lead at JPL, said:
“Future observations of this feature will provide good tests of dynamical models of the Titan circulation, chemistry, cloud and aerosol processes in the upper atmosphere.”
Polar vortices are not unique to Saturn in our solar system; they’ve also been seen on Jupiter, Neptune, Venus and Earth.