The North Pole of Saturn is famous for sporting a large hexagonal storm. And if that wasn’t weird enough, scientists have observed the storm also changing color.
When photographed in 2012, the storm was a light blue, but almost four years later it appears to have turned golden. NASA think that the change in seasons is responsible for the color-shift. The Northern Hemisphere of the ringed planet will have its summer solstice in May 2017.
The polar region has experienced continuous sunlight since 2009, and it might have reached a point where it generates more photochemical reactions in the upper atmosphere, and these aerosols might concentrate in a haze.
Changing in atmospheric circulation could also play a role in the discoloration, although it might still be caused by seasonal effects.
The hexagonal storm on the North Pole of Saturn as it looked in 2012 and how it looks now. Is it black and blue or white and gold? NASA/ESA/ASI
Changes in circulation are very interesting since it’s the complex and turbulent atmosphere of Saturn that creates the hexagonal feature. Simulations tested last year suggest that the storm is an eastward jet wind rotating at the same speed of the planet and the “hexagonality” is formed by small perturbations in the atmosphere.
The hexagonal storm was first spotted by the Voyager probes in the early 1980s, suggesting it is a lasting feature on Saturn.
The latest images were taken by Cassini, a collaboration between NASA, ESA, and the Italian Space Agency. The spacecraft has been orbiting around Saturn since 2004 and it will continue to study the ringed planet and its satellites until the end of its mission next year.
On November 29, Cassini will do a flyby of Titan (Saturn’s largest Moon), which will send it into an orbit closer to the main rings, leading to the Grand Finale mission, when the scientists will direct the probe into Saturn.