The north pole of Saturn is surrounded by a bizarre belt of air currents known as the hexagon, a six-sided turbulent stream that has persisted for decades, if not centuries. NASA’s Cassini probe has just obtained a new high-resolution movie of the hexagon; the movie has been assembled from images taken by Cassini’s cameras over a 10-hour period, which comprise the first complete view of Saturn from above down to approximately 70 degrees north latitude.
According to a NASA Jet Propulsion Labroratory press release, Cassini’s images reveal that the hexagon is a vast jet stream 20,000 miles across and moving at 200 miles per hour. The scope and longevity of the hexagon are probably attributable to the lack of physical barriers on the gas-giant Saturn.
NASA took advantage of Saturn’s northern spring to obtain the unprecedented images. The northern spring began in August 2009, and by late 2012, sunlight was illuminating the interior of the hexagon. Cassini’s images also show small vortices rotating in the opposite direction of the hexagon; the largest such vortex is 2,200 miles wide, twice the size of the largest hurricane ever documented on Earth. In addition to the hexagon and the small vortices, there is a storm raging directly over the pole. The images also revealed that the hexagon is acting as a barrier to large haze particles and instead surrounds a concentration of smaller aerosols.
The new Cassini images were analyzed in false color, which makes it easier to discern differences among the particles suspended in Saturn’s atmosphere. Cassini also used its visual and infrared mapping spectrometer to capture a black-and-white version of the movie.
Cassini blasted off in 1997 and entered orbit of Saturn on July 1, 2004. Its mission is expected to come to an end in September 2017, but not before it sends back more stunning images and data of Saturn and its moons. Cassini scientists will continue to track the appearance of the hexagon as Saturn’s summer solstice approaches in 2017. As the solstice nears, lighting at the north pole will get even better.