New images showing Saturn's shimmering aurora over a two-day period are helping scientists understand what drives some of the solar system's most impressive light shows. This composite image, constructed from data obtained by NASA's Cassini spacecraft, shows the glow of auroras streaking out about 1,000 kilometers (600 miles) from the cloud tops of Saturn's south polar region. It is among the first images released from a study that identifies images showing auroral emissions out of the entire catalogue of images taken by Cassini's visual and infrared mapping spectrometer.
Auroras on Saturn occur in a process similar to Earth's northern and southern lights. Particles from the solar wind are channeled by Saturn's magnetic field toward the planet's poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. At Saturn, however, auroral features can also be caused by electromagnetic waves generated when the planet's moons move through the plasma that fills Saturn's magnetosphere.
The images are part of a new study that, for the first time, extracts auroral information from the entire catalogue of Saturn images taken by the visual and infrared mapping spectrometer instrument (VIMS) aboard NASA's Cassini spacecraft.
"Saturn's auroras are very complex and we are only just beginning to understand all the factors involved," Stallard said. "This study will provide a broader view of the wide variety of different auroral features that can be seen, and will allow us to better understand what controls these changes in appearance."
The composite image was made from 65 individual observations by Cassini's visual and infrared mapping spectrometer on Nov. 1, 2008. The observations were each six minutes long.
"Detailed studies like this of Saturn's aurora help us understand how they are generated on Earth and the nature of the interactions between the magnetosphere and the uppermost regions of Saturn's atmosphere," said Linda Spilker, Cassini project scientist, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/home/index.cfm . The visual and infrared mapping spectrometer team homepage is at http://wwwvims.lpl.arizona.edu .
Image credit: NASA/JPL/University of Arizona/University of Leicester