Saturn’s North Pole (Cassini-Huygens, 2007 and 2008)

In November 1980, planetary scientists eagerly examined transmissions received from the Voyager 1 spacecraft as it sped past Saturn. And with good reason! Amid those transmissions was the first image of Saturn’s North Pole – a region that’s virtually impossible to see from Earth, and, depending on the degree by which Saturn is tilted, can be cloaked in darkness for up to 15 years at a time (and you thought your last winter was never going to end).

What those scientists saw, and later missions confirmed, was a decidedly bizarre feature in the gas giant’s atmosphere directly above the North Pole: a 15,000-mile-wide hexagon.

At this point, before we lose all but Weird Thing’s distinguished geometry geek readership (you know who you are, you magnificent bastards), it’s worth pointing out that hexagons naturally occur all over the place: basalt columns; beehive honeycombs; snowflakes; and even molecules offer some examples. Unfortunately the processes responsible for these formations by no means explain the feature on Saturn.  In fact, the planet’s thick atmosphere is one of the last places experts were prepared to find such a geometric oddity – even its South Pole has a reassuringly circular, terrifyingly enormous hurricane churning up the clouds.

A Comparison of Saturn’s Poles (Cassini-Huygens, 2008)

So why is it there? Besides dropping Jodie Foster – or, ideally, Matthew McConaughey – into the middle of the 60-mile-deep hexagon and seeing where she goes, a slightly less exciting experiment conducted by the Niels Bohr Institute in Denmark provided some intriguing results. And by slightly less exciting, we mean they stirred a bucket of water. What they found was that at certain speeds the water flow would interact with the edges of the cylindrical container to create rotating polygons with up to 6 corners.

As you may have already guessed, the experiment has a long way to go before it explains Saturn’s hexagon. For one thing, a colossal bucket isn’t sitting at the North Pole to provide distinct boundaries for the planet’s many complex layers of clouds to interact. Scientists have yet to figure out precisely how Saturn is creating a similar result with its multifaceted toolkit of jet streams and waves. Perhaps a more relevant explanation may be found in satellite observations of Hurricane Isabel (PDF) from 2003, wherein the storm’s eyewall alternated between pentagonal and hexagonal formations through unique combinations of smaller rotational features called mesovortices; showing us that even home grown storms can test and inevitably improve our equations of motion.

Satellite Observations of Hurricane Isabel in 2003 (PDF)

We’ll probably have plenty of time to figure out Saturn’s hexagon though. One of the most profound mysteries surrounding the formation (second only to its existence in the first place) is that it has stuck around as a stable feature in the 29 years or so since Voyager first observed it. As Saturn is currently in the unhurried process of tilting its North Pole towards the sun, scientists can soon point the Cassini-Huygens spacecraft’s superior optical instruments at the newly illuminated region to assist the relentless effort to discover answers (or more questions). Until then, we hope you’ll join us in simply appreciating this hexagon as one of the many weird things that makes our universe even more fascinating.

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