Saturn’s famous hexagon may tower above the clouds

Posted: September 5, 2018 by oldbrew in atmosphere, Clouds, News, solar system dynamics
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Saturn’s north polar vortex and hexagon along with its expansive rings. The hexagon is wider than two Earths [image credit: NASA]


Another case of observing something that wasn’t thought possible. As the report notes: ‘The presence of a hexagon way up in Saturn’s northern stratosphere, hundreds of kilometres above the clouds, suggests that there is much more to learn about the dynamics at play in the gas giant’s atmosphere.’

The long-lived international Cassini mission has revealed a surprising feature emerging at Saturn’s northern pole as it nears summertime: a warming, high-altitude vortex with a hexagonal shape, akin to the famous hexagon seen deeper down in Saturn’s clouds.

This suggests that the lower-altitude hexagon may influence what happens up above, and that it could be a towering structure spanning hundreds of kilometres in height, reports Phys.org.

When Cassini arrived at the Saturnian system in 2004, the southern hemisphere was enjoying summertime, while the northern was in the midst of winter. The spacecraft spied a broad, warm, high-altitude vortex at Saturn’s southern pole, but none at the planet’s northern pole.

A new long-term study has now spotted the first glimpses of a northern polar vortex forming high in the atmosphere as Saturn’s northern hemisphere approached summertime. This warm vortex sits hundreds of kilometres above the clouds, in a layer of atmosphere known as the stratosphere, and reveals an unexpected surprise.

“The edges of this newly-found vortex appear to be hexagonal, precisely matching a famous and bizarre hexagonal cloud pattern we see deeper down in Saturn’s atmosphere,” says Leigh Fletcher of the University of Leicester, UK, lead author of the new study.

“While we did expect to see a vortex of some kind at Saturn’s north pole as it grew warmer, its shape is really surprising. Either a hexagon has spawned spontaneously and identically at two different altitudes, one lower in the clouds and one high in the stratosphere, or the hexagon is in fact a towering structure spanning a vertical range of several hundred kilometres.”

Saturn’s cloud levels host the majority of the planet’s weather, including the pre-existing north polar hexagon. This feature was discovered by NASA’s Voyager spacecraft in the 1980s and has been studied for decades; it is a long-lasting wave potentially tied to Saturn’s rotation, a type of phenomenon also seen on Earth in structures such as the Polar Jet Stream.

Its properties were revealed in detail by Cassini, which observed it in multiple wavelengths – from the ultraviolet to the infrared – using instruments including its Composite Infrared Spectrometer (CIRS).

However, at the start of the mission this instrument could not peer further up in the northern stratosphere, which had temperatures around -158 degrees Celsius – some 20 degrees too cold for reliable CIRS infrared observations – leaving these higher-altitude regions relatively unexplored for many years.

Continued here.

Comments
  1. ivan says:

    As a SF fan of many years I can’t help wondering…

    There could be something natural about this but the size does leave space for wonder, maybe there is something else at work.

  2. oldbrew says:

    “The edges of this newly-found vortex appear to be hexagonal, precisely matching a famous and bizarre hexagonal cloud pattern we see deeper down in Saturn’s atmosphere,”

    Hard to see any reason why the two hexagons would not be related.

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