Massive hexagon discovered first in the Southern Hemisphere of Saturn, by Voyager Spacecraft, might have climbed up towards the Northern Pole.

Saturn has always been a planet of surprises and a recent study shows that the things haven’t changed much. The Cassini Spacecraft, which was built collectively by ESA, NASA, and the Italian Space Agency, found a strange hexagon at the Northern Pole of this gas giant. Although scientists found a hexagonal high-altitude vortex at the Southern Pole in 2004 as Cassini arrived at the Saturnian system, it is the first sighting of such a structure at the Northern Pole.

Previously, researchers believed that this jet stream of moving air (hexagon) was limited to the clouds of the Troposphere, a layer of Saturn’s atmosphere. According to an estimate of the researchers, the air inside this 32,000 kilometers wide hexagon travels at a speed of 320 km/h. However, the latest findings reveal that this warm vortex stretches into the Stratosphere which lies hundreds of kilometers above these clouds. An interesting thing is that Cassini found this hexagon in the Southern Hemisphere of Saturn during summertime in these regions and same is the case with this latest discovery. The structure was observed during the spring and summer of the Northern Hemisphere. Leigh Fletcher, the Lead Author of the study, mentioned that in the following words:

“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. 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 kilometers.”

The Voyager Spacecraft of NASA got a glimpse of this hexagon when they flew past Saturn in early 1980s. Having said that, detailed information about the properties of this mysterious structure were revealed only once Cassini reached the ringed planet. It used a variety of wavelengths to examine the planet ranging from the ultraviolet to the infrared. These inspections included the use of the Composite Infrared Spectrometer (CIRS). Given the length of a Saturnian year, the Stratosphere of Saturn remained unexplored for many years due to an extremely cold weather (-158^o C) as the instrument cannot operate reliably in such conditions. Sandrine Guerlet, a Co-author of the study, referred to that and said,

“One Saturnian year spans roughly 30 Earth years, so the winters are long. Saturn only began to emerge from the depths of northern winter in 2009, and gradually warmed up as the northern hemisphere approached summertime. We were able to use the CIRS instrument to explore the northern stratosphere for the first time from 2014 onwards. As the polar vortex became more and more visible, we noticed it had hexagonal edges, and realized that we were seeing the pre-existing hexagon at much higher altitudes than previously thought.”

The vortex discovered in the Northern Hemisphere is not as mature as its Southern counterpart. Similarly, significant variations were observed in the dynamics of both the vortices. The researchers concluded that the appearance of the hexagon is somehow related to the change of seasons because they observed nothing at the South Pole, this time around. Fletcher mentioned that by saying,

“This could mean that there’s a fundamental asymmetry between Saturn’s poles that we’re yet to understand, or it could mean that the north polar vortex was still developing in our last observations and kept doing so after Cassini’s demise.”

Despite locating a similar structure at the Northern Pole of Saturn, scientists consider it highly unlikely that it is the same hexagon which was seen in the Southern Hemisphere. Having said that, Fletcher did refer to a possible mechanism called ‘Evanescence’ which might have taken the same hexagon into the Stratosphere. His frustration was clearly evident as he talked about the demise of Cassini which could have offered key information in this regard. Fletcher praised the deceased spacecraft in the following words:

“The Cassini spacecraft continued to provide new insights and discoveries right up to the very end. Without a capable spacecraft like Cassini, these mysteries would have remained unexplored. It shows just what can be accomplished by an international team sending a sophisticated robotic explorer to a previously unexplored destination — with results that keep flowing even when the mission itself has ended.”