The Swirling Storm Above Saturn’s North Pole Changed Colors

The years-long shift may be a sign of changing seasons

Two natural color images from NASA's Cassini spacecraft show the changing appearance of Saturn's north polar region between 2012 and 2016. NASA/JPL-Caltech/Space Science Institute/Hampton University

Jupiter’s Great Red Spot is usually the cosmic storm that gets all the attention, but the next gas giant over has a swirling weather system of its own. The massive hexagonal-shaped storm sits atop Saturn’s north pole and is big enough to swallow Earth whole. But oddly, over the last several years, the swirling shape has changed colors.

The “hexagon,” as NASA astronomers refer to the storm, is a fascinating weather system caused by six different jet streams. But since 2012, the light blue form slowly shifted to a pale gold color—the change all captured by the Cassini spacecraft, The Guardian reports.

Researchers are still investigating possible causes for the color change, but initial analysis suggests that it may have something to do with the planet's seasons, according to a NASA press release.​ 

The idea is that as the planet shifted away from the sun during its years-long winter between 1995 and 2009, and the vortex likely flushed atmospheric particulate out of the region, turning it blue. The weather patterns of the hexagon essentially barricades off the region, preventing particulate flooding back in. But now that Saturn’s northern hemisphere is starting to shift back into summer, the constant sunlight is reacting with the atmosphere to produce more particulate, turning the area gold, Samantha Mathewson reports for

Shifting seasons may not be the only reason Saturn’s north pole is turning gold again. Wind patterns around the gas giant could change as the sun’s rays heat up Saturn’s atmosphere, according to the press release. And of course, it could be a combination of these factors.

In any case, it’s lucky that the NASA scientists were able to witness this phenomenon at all. Each year on Saturn is equal to about 29 Earth years, and Cassini has only been orbiting the gas giant since 2004. That put it in exactly the right spot to witness the color-shifting pole as it moved through its winter equinox and started back towards summer, Maddie Stone writes for Gizmodo.

Though Cassini’s mission is scheduled to come to an end next year, the wealth of data it has beamed back has given NASA scientists a fresh look at weather on a different planet. There may only be a few more months left in the craft's life, but there still potential for more discoveries to come.

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