Cassini's infrared instrument studied the auroral display between October 2006 and June 2007. Images, released this week, show both a bright ring, which is visible from Earth, as well as infrared auroral emissions within the polar cap. "This aurora appears to be unique to Saturn and cannot be explained using our current understanding of Saturn's magnetosphere," Stallard and colleagues wrote in Nature. "There are periods when the polar aurora is relatively quiet, with the emission taking the form of localized bright spots, low levels of patchy emission across the pole or extended arcs," they said. "However … they sometimes become as bright, or brighter, than the main auroral oval, filling the region between 82 degrees North and the pole with emission, unlike anything that has been observed in previous observations," the authors wrote. Cassini found that the aurora can completely disappear in a period of time as short as 45 minutes. "The bright polar aurora appears to be unique to Saturn," Stallard said. Related Links: Discovery Space: IM Interview: Pinging Saturn's Moon Titan |
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