Scientists have discovered a wavepattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years, according to two studies published Thursday in journal Nature.
The discovery is the result of a 22-year campaign observing Saturn from Earth, and the Cassini spacecraft's observations of temperature changes in the giant planet's atmosphere over time.
The Cassini infrared results, which appear in the same issue of Nature as the data from the 22-year ground-based observing campaign, indicate that Saturn's wave pattern is similar to a pattern found in Earth's upper atmosphere.
The earthly oscillation takes about two years. A similar pattern on Jupiter takes more than four Earth years. The new Saturn findings add a common link to the three planets.
Glenn Orton of NASA's Jet Propulsion Laboratory says patience is the key to studying changes over the course of a Saturnian year, the equivalent of about 30 Earth years.
"You could only make this discovery by observing Saturn over a long period of time," said Orton, lead author of the ground-based study.
The wave pattern is called an atmospheric oscillation. It ripples back and forth within Saturn's upper atmosphere. In this region, temperatures switch from one altitude to the next in a candy cane-like, striped, hot-cold pattern. These varying temperatures force the wind in the region to keep changing direction from east to west, jumping back and forth. As a result, the entire region oscillates like a wave.
A "snapshot" of the hot-cold temperature patterns in Saturn's atmosphere was captured by the Cassini Composite Infrared Spectrometer. Along with Earth-based data, the "snapshot" also uncovered other interesting phenomena. Among them are: the temperature at Saturn's equator switches from hot to cold, and temperatures on either side of the equator switch from cold to hot every Saturn half-year.
Mike Flasar, co-author of the Cassini paper, said that Cassini helped define this oscillation in combination with the ground observation campaign.
"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 Flasar. "Without Cassini, we might never have seen the structure of the oscillation in detail."
Source:Xinhua
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