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Cassini keeps on brining us surprises from Saturn and its moons. Recently, it helped us narrow down the length of a day on Saturn. Now, infrared data from the spacecraft confirms a hot, hexagonal cyclone spinning away at the north pole of of the planet.
The south polar hot spot had been previously observed, and was thought to be due to the sunny conditions, as this region of Saturn is currently in summer. Observations from the Cassini spacecraft in early 2007 revealed that Saturn also has a hot cyclone spinning away at the north pole, despite the fact that this region hasn’t seen the Sun in over 10 years.
Voyager 1 and 2 took observations of the north pole in the 1980s, but the Cassini data gives a more detailed view of the features. It was thought that the sunlight was causing the hot spot at the south pole.This new data, though, adds a bit of mystery to the mechanisms causing the cyclones. They appear to be permanent fixtures of the planet, rather than caused by the seasons.
“The hot spots are the result of air moving polewards, being compressed and heated up as it descends over the poles into the depths of Saturn. The driving forces behind the motion, and indeed the global motion of Saturn’s atmosphere, still need to be understood,” said planetary scientist Leigh Fletcher of the University of Oxford, England, and lead author of the paper published in Science on January 4th.
The northern cyclone also has the peculiar shape of a hexagon, something absent from the southern cyclone. The recent findings place the hexagon higher up in the clouds than previously shown, though the cause of the curious shape is still unexplained.
Neptune is home to a hot spot on its southern pole, and the Great Red Spots on Jupiter is another example of long-lasting cyclonic features on a gas giant. Knowing more about the cyclones on Saturn will help us understand similar weather patterns on the other gas giants.
Winter lasts 15 years on Saturn, and in the next few years the north pole will again start to see sunlight, possibly changing the features of the cyclone and giving scientists a better understanding of how the Sun affects these tricky twisters.
Source: JPL Press Release