By Dean Murray A “mysterious” 10-sided structure, known as a decagon, has been discovered in Saturn’s atmosphere. Using the Hubble Space Telescope, images from amateur astronomers, and observations from a University of Leicester scientist, an international team of scientists has revealed the presence of a wave around the planet’s South Pole that is nearly twinned with a long-lived hexagonal structure at its North Pole. Details of the discovery, which the University of Leicester described as “mysterious”, have been published in the journal Science Advances on Wednesday, September 2, and adds to the continuing mystery of atmospheric phenomena in the gas giants of our solar system. When the Voyager 1 and Voyager 2 spacecraft flew by Saturn in 1980 and 1981, one of their many discoveries was the presence, within the planet’s clouds, of a hexagonal wave surrounding its north pole. The hexagon has persisted to this day, for more than one Saturnian year (which is equivalent to about 30 Earth years). The feature, called a decagon, is the first large, regular-sided pattern observed in Saturn’s southern hemisphere. (NASA/ESA/STScI/A. Sánchez-Lavega via SWNS)Despite the symmetry in the distribution of winds and atmospheric dynamics throughout the planet, in all the years since then, no similar structure had been observed in the southern hemisphere. But recently, as the planet’s southern hemisphere became more visible from Earth between 2023 and 2025, images taken by amateur astronomers and the Hubble Space Telescope (HST) revealed not a hexagon but a decagonal structure (a 10-sided polygon) around the planet’s south polar region. Images subsequently obtained by the HST in 2024 and 2025, as well as those taken with ground-based telescopes, confirmed its existence. Co-author Leigh Fletcher from the School of Physics and Astronomy at the University of Leicester said: “Saturn still has the ability to surprise us; given the season, Saturn’s southern hemisphere is emerging from more than a decade in winter darkness. Something has clearly changed during that long winter when we weren’t looking, presenting us with this impressive new feature around the South Pole.” (NASA/ESA/STScI/A. Sánchez-Lavega via SWNS) Lead author Agustín Sánchez-Lavega of the University of the Basque Country EHU said: “This research raises many fundamental questions about atmospheric phenomena in gas giants. Why is Saturn the only planet that forms this type of polygonal waves? 5- and 8-sided polygonal arrangement of cyclones surrounding Jupiter’s poles?” Fletcher adds: “What’s really exciting about this work is the involvement of amateur observers with their home telescopes, sharing their images online and searching for new discoveries in Saturn’s clouds. It was their data that first hinted that something interesting was happening.” The hexagon itself is now hidden from view, as the North Pole disappears in autumn and winter. Who knows if it will still be there the next time we can look? And how long will this new decagon remain?” Agustín Sánchez-Lavega adds: “More observations in the coming years, as the visibility of the planet’s southern hemisphere gradually improves, will help characterize it and develop advanced models that will allow us to solve this intriguing atmospheric mystery.” The post Mysterious 10-sided structure discovered on Saturn appeared first on Talker.
