Image of the Day: 22/9/14

(Photo Credit: NASA/JPL-Caltech/SSI/Hampton University)

Saturn is a gigantic ball of rotating gas that is completely unlike Earth in many ways but one: its weather. Our home planet and Saturn both experience similar weather phenomenons, however the gas giant is also home to some of the most bizarre weather witnessed in our Solar System, such as this swirling storm, known as “the hexagon”, which was photographed by the NASA/ESA Cassini spacecraft.

The hexagon is an intense, six-sided jet stream at Saturn’s north pole that spans some 30,000 km across and hosts howling 320 km/h winds that spiral around a massive storm that rotates anticlockwise at its heart.

A number of small vortices rotate in the opposite direction to the central storm and are dragged around with the jet stream, therefore creating a terrifically turbulent region – a hurricane on Earth may last a week or more but the hexagon has been raging for decades, and shows no signs of ceasing any time soon.

This false-colour image of the hexagon was captured using ultraviolet, visible and infrared filters to highlight the different regions of the storm.

The dark centre of the image shows the large central storm and its eye, which is up to 50 times bigger than a terrestrial hurricane eye.

The small vortices show up as pink-red clumps while towards the lower right of the frame is a white-tinted oval storm that is 3,500 km wide — the largest of the vortices and twice the size of the largest hurricane ever recorded on Earth.

The darker blue region within the hexagon is filled with small haze particles, whereas the paler blue region is dominated by larger particles. This divide is caused by the hexagonal jet stream acting as a barrier — large particles cannot enter the hexagon from the outside.

These large particles are created when sunlight shines onto Saturn’s atmosphere, a process that only started relatively recently in the northern hemisphere during the beginning of northern spring in August 2009.

The Cassini spacecraft will continue to track changes in the hexagon, monitoring its contents, shape and behaviour as summer reaches Saturn’s northern hemisphere in 2017.