Saturn's Aurora Could Hold Key to Radio Pulse Mystery

Those fortunate enough to see the aurora borealis firsthand rave about the spectacular kaleidoscopic effects. They result from the collision of charged particles dumped into the Earth's magnetosphere by the solar wind. The lights tend to only be visible in polar regions because those particles follow the Earth's magnetic field lines -- which fan out from the vicinity of the poles.

SLIDE SHOW: What is the Aurora Borealis?

WATCH VIDEO: NASA and ESA astronomers released movies of Saturn's northern and southern lights, glimpsed edge-on for the first time by the Hubble Space Telescope.

But Earth isn't the only planet with an aurora: that ringed beauty, Saturn, also puts on the occasional light show. And a new paper in Geophysical Research Letters (via the American Geophysical Union) reports on a startling new finding that Saturn's auroras might be related to another mystery surrounding the planet: that of pulsed radio emissions first detected when the Voyager satellite missions flew past in 1980 and 1981.

Since then, astronomers have continued to measure the pulses, and initially they thought the timing of the pulses -- a period close to 11 hours -- represented the rotation of the planet. But other measurements revealed a varying pulse rate for those emissions, which was perplexing, to say the least.

Scientists figured the radio waves were caused by charged particles hurtling towards the planet's magnetic poles, which would connect them to the observed aurora phenomenon, but they hadn't managed to find a corresponding pulsation in Saturn's aurora.

Until now.

BIG PIC: Hubble Snaps Saturn With Rings Edge-On (plus aurora).

Jonathon Nichols of the University of Leicester and his co-authors collected Hubble images of Saturn's auroras taken between 2005 and 2009 and stacked them all on top of each other, using the "clock" of the radio pulsing to organize the data. And there it was: a pulsing ultraviolet glow, waxing and waning about once every Saturnian day -- a kind of "auroral heartbeat."

So the pulsed radio emissions and the waxing and waning of the aurora are indeed connected, pulsing in tandem; the radio emissions are the result of the processes that create Saturn's aurora. This is "a significant step toward solving the mystery of the variable radio period," said Nichols. NASA/ESA's Cassini spacecraft now orbiting Saturn is expected to yield further insight into this phenomenon.

Image credit: NASA, ESA and Jonathan Nichols (University of Leicester).