Cassini images chronicle massive Saturn storm
Heavy storms may ravage Earth from time to time, but our planet has got nothing on Saturn: the planet was pummelled by a string of storms that lasted for 200 days. The biggest in over 20 years, this record-breaking storm season was captured in images and animated movies from the Cassini spacecraft during the Cassini-Huygens mission that is unlocking the mysteries of the renowned ringed planet. The brightly coloured images and animations chronicle the birth of the tempest, extending around 15 000 kilometres from north to south. Apart from the initial images, Cassini also detected the storm's electrical activity via the use of its radio and plasma wave instrument. Based on this information, the scientists from Europe and the United States discovered that the electrical activity was a convective thunderstorm. While the convecting phase reached its culmination in June of this year, the planet's atmosphere is still awash with turbulent clouds. The last time Saturn encountered a storm of this size was in 1903; it lasted for 150 days back then. 'The Saturn storm is more like a volcano than a terrestrial weather system,' explains Andrew Ingersoll from the California Institute of Technology in the United States, a member of the Cassini imaging team. 'The pressure builds up for many years before the storm erupts. The mystery is that there's no rock to resist the pressure - to delay the eruption for so many years.' Hundreds of images of this storm were obtained by Cassini, to be collated in the imaging team's 'Saturn Storm Watch' mission. Images are used to assess the storm in between other scheduled observations of either Saturn or its rings and moons. Scientists can use the latest images to trace back the subtle changes on the planet that preceded the storm's formation, and to shed new light on the development of this storm. The images and animations also provide information about wind speeds and altitudes at which its changes occur, according to the scientists. The storm made its initial appearance at around 35°north latitude on Saturn and then completely enveloped the planet, expanding into an area of 5 billion square kilometres. 'This new storm is a completely different kind of beast compared to anything we saw on Saturn previously with Cassini,' says Kunio Sayanagi from the University of California, Los Angeles in the United States, also a member of the imaging team. 'The fact that such outbursts are episodic and keep happening on Saturn every 20 to 30 years or so is telling us something about deep inside the planet, but we have yet to figure out what it is.' There may well be more novel and exciting news reaching us from this quarter in the future: researchers plan to work on this campaign for another six years. Says Cassini imaging team leader Carolyn Porco, a scientist at the Space Science Institute in the United States: 'Seven years of taking advantage of such opportunities have already made Cassini one of the most scientifically productive planetary missions ever flown.' The American National Aeronautics and Space Administration (NASA), the European Space Agency (ESA) and the Italian Space Agency (ASI) are working together on the Cassini-Huygens mission.For more information, please visit: Cassini:http://www.nasa.gov/mission_pages/cassini/main/index.htmlEuropean Space Agency (ESA):http://www.esa.int/esaCP/index.htmlNASA:http://www.nasa.gov/home/index.html
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