Saturn’s Hexagon Structure Could be Caused by Subsurface Vortexes

Saturn‘s rings are not the only unique trait the planet boasts. It also has a six-sided feature at its north pole, which researchers first discovered when NASA‘s Voyager 2 probe paid a visit to Saturn back in 1981.  

The planet’s hexagon feature is stunning but also peculiar as it only appears at the north pole. In a new study, a team of experts analyzed the dynamics of Saturn’s stirring gas in order to understand what kind of planetary fluid process is creating the enigmatic structure.

Saturn’s Beauty Mark  

Back in 2019, Rakesh Yadav and Jeremy Bloxham from the Department of Earth and Planetary Sciences at Harvard University in Cambridge, Massachusetts, carried out a month-long computer simulation to figure out the physics behind Saturn’s hexagonal feature.  

As per their findings, atmospheric flows within the planet generate large and small vortexes close to the north pole. A powerful horizontal jet that moves about 60 degrees latitude above the equator gets pressed and confined by these vortexes, which shapes the rim of the hexagon.  

NASA’s Cassini spacecraft captured this natural-color view of Saturn’s north pole on July 22nd, 2013. [Image: NASA/JPL-Caltech/Space Science Institute]
One of the main points of the study, as per Yadav, is that the vortexes do exist, but stir deep beneath the cloud tops and are, therefore, mainly invisible to probes that have flown over Saturn. After Voyager 2 data was sent to Earth, researchers theorized that the structure could have been caused by subsurface cyclones as the new study implies.  

Although NASA’s Cassini spacecraft observed Saturn and its data from 2004 to 2017 helped scientists understand more about the planet’s fluid processes, the hypothesis about subsurface vortexes was not supported enough when the probe wasn’t able to observe prominent signs of their existence, Yadav said.  

The scientist carried out model simulations of deep, violent compressible convection, a phenomenon that takes place when the material at the bottom of a thick and multilayered substance of liquid or gas is hot at the bottom and cool at the top. That discrepancy in temperature causes the material to move in a circular up-down pattern; because the convection is pervasive across nature, hurricanes and tornadoes are created on Earth.  

Subsurface Vortexes  

According to Yadav, the event is similar to what happens when someone puts cold water into a pot, lights up the stovetop, and begins to heat up the water. The heat from the bottom of the pan stirs up the water as the water sends hear upwards to the colder surface.  

Saturn’s hexagon in color filters and a complete view from the north pole. [Image: NASA/JPL-Caltech/SSI/Hampton University]
The simulation managed to capture the physics behind the one-pole hexagon and provided the possibility that in the past, Saturn may have had a hexagon in the south pole and not in the north pole, or perhaps such a structure, at each pole, Yadav said.  

The experiment did not get a hexagonal shape in the end, but it produced an angled object with nine sides rather than six. However, the system behind the simulation suggests that subsurface vortexes are behind the feature.  

“It’s very possible that with different conditions, we can easily get six edges instead of nine,” Yadav said.  

The computer simulations were difficult to run, and scientists can only perform small studies within existing parameters. However, the team hopes to be able to run more cases in the future to learn more about Saturn’s unique signature.  

The paper detailing this work was published on June 8th in the journal Proceedings on the National Academy of the Sciences. 

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