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Astronomers have discovered a 10-sided wave pattern swirling in the icy ammonia clouds over Saturn’s south pole, revealing a new atmospheric feature on the gas giant.
Hubble Space Telescope Spots Saturn Decagon
The newly identified decagon emerged in Hubble imagery captured in 2023, according to a study published in the journal Science Advances. Lead author Agustin Sanchez-Lavega of the University of the Basque Country stated that earlier observations missed the formation because Saturn’s south pole was tilted away from Earth between 2017 and 2023, keeping the region out of view. Researchers suspect the wave pattern developed during that hidden window and is still evolving.
Individual sides of the sprawling decagon already exceed 10,000 miles, or 16,700 kilometers, in length. The discovery demonstrates that Saturn’s atmospheric dynamics are more complex than previously understood. “The unique hexagon is not as extraordinary as we thought,” Sanchez-Lavega said in an email.
Comparing Saturn’s Polar Polygons
While all gas giants in the solar system host wave-spawning atmospheric disturbances, Saturn remains the only planet known to churn out distinct polygonal shapes bounded by straight lines. Both the northern hexagon and the southern decagon sit atop powerful jet streams, but their operational mechanics differ significantly.
According to the research team, the northern hexagon is practically stationary, whereas the southern decagon migrates eastward at a steady speed of 6 mph, or 10 kph. Leigh Fletcher of the University of Leicester, who measured the winds within the decagon using the European Southern Observatory’s Very Large Telescope in Chile, noted in a statement that “Saturn still has the ability to surprise us.”
Future Observations and Unresolved Questions
Scientists are now working to determine why these geometric patterns form exclusively on Saturn. Sanchez-Lavega suggested the waves might share mechanical similarities with polygonal cyclone arrangements observed on Jupiter. Improved viewing angles of Saturn’s southern hemisphere over the coming years will allow astronomers to track the decagon’s evolution and test these theories.
Researchers remain uncertain whether the decagon will match the longevity of the northern hexagon, which has persisted in spacecraft observations for more than 40 years—outlasting a full Saturnian year, equivalent to 30 Earth years. “For the time being, all I can confirm is that the decagon is still there,” Sanchez-Lavega said.
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