By Sunanda Creagh, The Conversation
The US space agency has released fresh pictures of a hurricane with a 2000km wide eye locked over Saturn’s north pole and spinning at around four times the speed of earthly hurricane winds.
The pictures, captured by NASA’s Cassini spacecraft, show the huge hurricane being held in one spot inside a hexagon-shaped weather pattern.
A video of the storm can be seen here.
“We did a double take when we saw this vortex because it looks so much like a hurricane on Earth,” Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena said in a NASA press release.
“But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapour in Saturn’s hydrogen atmosphere.”
The eye of the Saturn hurricane is over 20 times bigger than the average hurricane eye on Earth, with clouds at its edge moving at up to 150 metres per second.
While Earth hurricanes can sweep across large areas, the Saturn hurricane was held in one place as far north as it could go.
“The polar hurricane has nowhere else to go, and that’s likely why it’s stuck at the pole,” said Kunio Sayanagi, a Cassini imaging team associate at Hampton University in the US.
Dr Alice Gorman, a space expert at Flinders University, said storms on other planets were not unusual.
“You do get some fairly big weather events on these other planets. When Voyager 2 went past Neptune in 1989 they discovered, to their surprise, it was much more dynamically active in weather terms than expected,” she said.
“Some planets don’t have much atmosphere or gases or clouds, like Mars, so it doesn’t have a huge amount of storms. But the gas giants, like Saturn and Jupiter, do have quite a lot.”
Dr Jonti Horner, a Post Doctoral Research Fellow and space expert at the University of NSW, said the pictures looked awesome.
“I think the discovery is particularly interesting to me because it shows us that Saturn has one of these huge vortices at each pole – the equivalent storm at the south pole was imaged by Cassini back in 2006. The southern storm, too, was surrounded by a hexagon,” he said.
“I suspect people who study planetary atmospheres and weather are likely having a field day.”
Dr Horner said that the fact Saturn’s poles both feature these systems was very intriguing.
“It’s interesting to note that, on Earth, we get storms near the pole that look superficially like hurricanes – they’re called Polar Lows. They have an eye-like structure, just like hurricanes – but they’re considered to be a distinct type of weather system. They don’t sit right over the pole, though, and are far, far smaller than the Saturnian system (even compared to the size of the planets involved), so probably aren’t directly comparable either.”