Cassini Finds Mysterious New Aurora on Saturn

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.
Carolina.Martinez@jpl.nasa.gov

IMAGE ADVISORY: 2008-208 Nov. 12, 2008

Cassini Finds Mysterious New Aurora on Saturn

Saturn has its own unique brand of aurora that lights up the polar cap, unlike any other planetary
aurora known in our solar system. This odd aurora revealed itself to one of the infrared
instruments on NASA's Cassini spacecraft.

"We've never seen an aurora like this elsewhere," said Tom Stallard, a scientist working with
Cassini data at the University of Leicester, England. Stallard is lead author of a paper that
appears in the Nov. 13 issue of the journal Nature. "It's not just a ring of auroras like those we've
seen at Jupiter or Earth. This aurora covers an enormous area across the pole. Our current ideas
on what forms Saturn's aurora predict that this region should be empty, so finding such a bright
aurora here is a fantastic surprise."

The new views are available online at: http://www.nasa.gov/cassini and
http://saturn.jpl.nasa.gov.

Auroras are caused by charged particles streaming along the magnetic field lines of a planet into
its atmosphere. Particles from the sun cause Earth's auroras. Many, but not all, of the auroras at
Jupiter and Saturn are caused by particles trapped within the magnetic environments of those
planets.

Jupiter's main auroral ring, caused by interactions internal to Jupiter's magnetic environment, is
constant in size. Saturn's main aurora, which is caused by the solar wind, changes size
dramatically as the wind varies. The newly observed aurora at Saturn, however, doesn't fit into
either category.

"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."

The new infrared aurora appears in a region hidden from NASA's Hubble Space Telescope,
which has provided views of Saturn's ultraviolet aurora. Cassini observed it when the spacecraft
flew near Saturn's polar region. In infrared light, the aurora sometimes fills the region from
around 82 degrees north all the way over the pole. This new aurora is also constantly changing,
even disappearing within a 45 minute-period.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency
and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California
Institute of Technology in Pasadena, manages the mission for NASA's Science Mission
Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at
JPL. The visual and infrared mapping spectrometer team is based at the University of Arizona,
Tucson.

-end-

To remove yourself from this mailing, please go to http://www.kintera.org/TR.asp?a=ftIPI3PPJnKVIgI&s=jtK0I4NJJfIMK3PPItF&m=irKSK6NLJkJ1G

To remove yourself from all mailings from NASA Jet Propulsion Laboratory, please go to http://www.kintera.org/TR.asp?a=iwKVJcM1IqJ2JqL&s=jtK0I4NJJfIMK3PPItF&m=irKSK6NLJkJ1G