Much like Earth’s northern and southern lights, Saturn’s aurora is triggered when charged particles from solar winds are channeled toward the poles by the planet’s magnetic field. At the poles, these particles interact with charged gas or plasma in the upper atmosphere and emit light. Saturn’s aurora can also be caused by electromagnetic waves generated when its moons move through its magnetosphere.

Cassini has already delivered some gorgeous examples of these colorful curtains of light.

“But to understand the overall nature of the auroral region we need to make a huge number of observations — which can be difficult because Cassini observation time is in high demand,” said astronomer Tom Stallard of the University of Leicester in the UK in a press release.

Rather than snapping photos of the aurora directly, Stallard and his colleagues are sifting through 7,000 images from Cassini’s VIMS (Visual and Infrared Mapping Spectrometer) instrument to piece together fragments of aurora into a more complete picture.

“As a whole, this wide set of observations will allow us to understand the aurora in general,” Stallard said. Stallard will present preliminary results at the European Planetary Science Congress in Rome on September 24.

The movie shows how the aurora vary over the course of a Saturnian day (about 10 hours and 47 minutes). On the noon (left) and midnight (right) sides, the aurora brighten significantly for several hours at a time, suggesting the brightening is connected with the direction of the Sun. Other features rotate with the planet below, reappearing at the same time and the same place on the second day. This suggests that these features are directly controlled by the direction of Saturn’s magnetic field.

So far, Stallard and his colleagues have made it through about 1,000 out of 7,000 VIMS images of Saturn’s auroral region.

Images and video: NASA/JPL/University of Leicester/University of Arizona

See Also:

• Video: Saturn’s Spectacular Aurora in Action
• New Aurora Webcam Captures Spectacular Videos, Images
• This Summer’s Sexiest Images From Saturn
• Cassini Gets Life Extension to Explore Saturn Until 2017

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Authors: Lisa Grossman

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