November 13, 2008—Saturn has given scientists a light show like nothing they've ever seen, NASA announced Wednesday.

The Cassini orbiter has captured a unique aurora (shown in blue) on the ringed planet that illuminates much of its northern polar cap.

Auroras occur when charged particles stream across a planet's magnetic field lines and into its atmosphere.

But they don't usually light up such a wide area.

"It's not just a ring of auroras like those we've seen at Jupiter or Earth," Tom Stallard, a scientist at the University of Leichester, U.K., said in a statement. He added that "finding such a bright aurora here is a fantastic surprise."

(Related: "Mysterious Cyclones Seen at Both of Saturn's Poles" [October 14, 2008].)

The newfound aurora is often elusive, sometimes disappearing within 45 minutes, the researchers say.

Explaining the oddity will undoubtedly unearth new laws of physics found only on Saturn, said Nick Achilleos of University College London.

—Christine Dell'Amore