Saturn's Atmosphere Does the Wave

The planet Saturn does the wave in its atmosphere, but it's only visible from Earth every 15 years, a new study finds.

Two decades of staring at the ringed planet in ground- and space-based studies paid off when scientists discovered a wave pattern similar to one found in Earth's upper atmosphere.

"You could only make this discovery by observing Saturn over a long period of time," said the ground study?s lead author Glenn Orton, a planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's like putting together 22 years worth of puzzle pieces, collected by a hugely rewarding collaboration of students and scientists from around the world on various telescopes."

Research from Orton?s study and a space-based one using the Cassini spacecraft is detailed in the May 8 issue of the journal Nature.

The wave pattern ripples back and forth in Saturn's upper atmosphere due to bands of different temperatures at various altitudes. Changing temperatures force the wind to keep whipping back and forth from east to west, causing the entire region to move like a wave.

NASA's Cassini spacecraft provided a space-based infrared snapshot of Saturn's wave in action, allowing scientists to compare it with similar atmospheric patterns on Earth and Jupiter. Earth's wave takes about two years and Jupiter's wave takes more than four Earth years, but changes on Saturn may occur over much longer periods of up to 30 Earth years, or one Saturn year.

"It's this great synergy of using ground-based data over time, and then getting up close and personal with the oscillation in Saturn's atmosphere through Cassini," said Mike Flasar, a principal scientist for Cassini at NASA's Goddard Space Flight Center in Greenbelt, Md., and co-author of the space-based study. "Without Cassini, we might never have seen the structure of the oscillation in detail."

Cassini's snapshot with its Composite Infrared Spectrometer further revealed that Saturn's equator flips from hot to cold. The temperatures on either side of the equator also apparently switch every Saturn half-year.

Longer study of Saturn may allow scientists to better understand this phenomenon, and particularly why the temperature switch happens as the sun is directly over Saturn's equator.

Such strange climate behavior is hardly new for Saturn, which has displayed baffling weather such as a swirling hexagon circling its north pole.

• VIDEO: The Hexagon on Saturn
• VIDEO: Enceladus, Cold Faithful
• IMAGES: Cassini's Latest Discoveries