Friday 10 October 2014

Image of the Day: New Cassini View of Saturn's Massive Hexagon Vortex




Wavy-polar-vortex



NASA's Cassini spacecraft captured this dramatic image of Saturn's geometric jet stream in July 2013 from about 605,000 miles (973,000 kilometers) away from the planet. The image — which NASA released this week provides a close up look at a vast storm system within the hexagonal weather pattern at the north pole of Saturn.



The storm looks very like a hurricane on Earth, but it is much bigger: the clear central eye of the storm is about 2000 km across – ten times the typical size on Earth – and clouds at the outer edge of the hurricane on Saturn are moving at more than 500 kph! One difference from terrestrial hurricanes is that this storm is locked into the weather system at the pole, rather than sweeping round the planet as happens on Earth.
The existence of this storm poses questions about both Saturn and Earth. Terrestrial hurricanes get their energy from warm ocean water; this system on Saturn does not have a handy warm ocean, although it does use a relatively small amount of water vapour within the hydrogen atmosphere. Understanding how this storm system evolves may shed light on the mechanisms of terrestrial storms.

Scientists have not seen the north pole so clearly in the past because it is only now emerging from winter. Cassini’s composite infrared spectrometer and visual and infrared mapping spectrometer detected the great hexagonal vortex, but now it is visible. Cassini is also getting better views of the poles because it is following more highly inclined orbits, using Titan’s gravity to change the angle.

Image credit: NASA/JPL-Caltech/SSI





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