Aurora discovered on Saturn
Scientists discover mysterious aurora on Saturn
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Thursday, 13, Nov 2008 12:01
Scientists have discovered a mysterious aurora on Saturn unlike any other in the solar system, including Earth's own northern lights.
An infrared camera aboard NASA's Cassini spacecraft spotted the aurora lighting up Saturn's polar cap – a surprise to scientists who were expecting this area to be empty.
"We've never seen an aurora like this elsewhere," said Tom Stallard, a scientists working with Cassini data at the University of Leicester.
"It's not just a ring of aurorae like those we've seen at Jupiter or Earth. This one covers an enormous area across the pole.
"Our current ideas on what forms Saturn's aurorae predict that this region should be empty, so finding such a bright one here is a fantastic surprise."
Aurorae are caused when charged particles stream along the magnetic field of a planet and into its atmosphere. On Earth these charged particles come from the solar wind - a stream of particles that emanates from the Sun.
Jupiter's main auroral ring is constant in size, while Saturn's main aurora changes size dramatically as the wind varies. The newly observed aurora at Saturn, however, does not fit into either category, the scientists say.
"Saturn's unique auroral features are telling us there is something special and unforeseen about this planet's magnetosphere and the way it interacts with the solar wind and the planet's atmosphere," said Nick Achilleos, Cassini scientist on the Cassini magnetometer team at the University College London.
"Trying to explain its origin will no doubt lead us to physics which uniquely operates in the environment of Saturn."