Hubble Snaps Saturn With Rings Edge-On

Feb. 11, 2010 -- Stunning global views of Saturn show aurora duets at the planet's poles, though the light shows are not of equal caliber.

Analysis of the images, taken by the Hubble Space Telescope, indicate magnetic fields in Saturn's northern hemisphere are stronger than those in the south. Scientists don't know why.

With Saturn at equinox -- with roughly equal amounts of sunlight falling on its northern and southern hemispheres -- and its rings edge-on toward Earth, scientists used the Hubble's ultraviolet camera to get a simultaneous look at the planet's poles.

Since the planet's magnetic fields are closely aligned with Saturn's rotational axis, scientists had expected the aurora to be the same. Like on Earth, aurora are caused when electrically charged particles from the sun become trapped in a planet's magnetic fields, causing atoms in the atmosphere to heat up and glow. The phenomenon is most apparent around the poles where magnetic fields are strongest.

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.

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Instead, scientists found that Saturn's northern aurora are brighter and more contained than those in the south, indicating a stronger magnetic field in the north, astronomer Jonathan Nichols, with the University of Leicester, told Discovery News.

The finding confirms earlier measurements from the Saturn-orbiting Cassini science probe, which used a magnetic compass to measure the fields.

"This is the first time we've actually been able to take sustained images of both poles of any planet," Nichols said.

He plans to follow up the observations with analysis to see if differences in the aurora brightness match differences in radio pulses emanating from Saturn’s northern and southern regions.

Boston University astronomer John Clarke said researchers already are preparing requests for additional time on Hubble to study the aurora while Cassini makes in-situ measurements.

Saturn is properly aligned for such views from Earth only once every 15 years.

Nichols published his findings in Geophysical Research Letters in December. The Hubble images were released Thursday.

Text by Irene Klotz

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