Scientists spot ten-sided structure on Saturn

A 10-sided atmospheric pattern has been identified around Saturn’s south pole, giving the planet a southern counterpart to the hexagon that has ringed its north pole for decades. NASA and the Space Telescope Science Institute said recent Hubble Space Telescope observations revealed a giant decagon embedded in a southern jet stream. A paper published September 2 in *Science Advances* said the feature was visible in Hubble data from 2023 and became clearer in 2025. The finding adds a new polygonal wave to one of the solar system’s most closely watched atmospheres. ### Where exactly is the ten-sided structure? The *Science Advances* paper said the decagon appears at planetographic latitudes of about 58 degrees south to 63 degrees south. The paper described it as a polygonal wave circling Saturn’s south polar region, rather than a solid object or surface feature. NASA said the wave sits within one of Saturn’s powerful jet streams. (science.nasa.gov) The agency and the European Space Agency said the structure extends through multiple layers of the atmosphere, indicating it is not limited to the visible cloud tops. ### How did scientists see it if Saturn’s south pole is hard to view? Hubble observations provided the key evidence. (science.org) The *Science Advances* paper said red-filtered Hubble images taken in October 2023 showed a 10-sided polygonal structure despite the relatively poor viewing angle of Saturn’s southern hemisphere. The Space Telescope Science Institute said researchers pieced together several years of Hubble observations and found hints of the pattern emerging before it became a clearly defined shape. (science.nasa.gov) NASA said the data showed the feature’s presence back to 2023. ### Is this the same kind of thing as Saturn’s famous hexagon? (science.org) Saturn’s north-pole hexagon is the closest comparison, but the two features are not identical. The *Science Advances* paper said Saturn has a long-lived, nearly stationary hexagon close to its north pole and that no similar wave had previously been reported in the southern hemisphere or elsewhere on the planet. (science.nasa.gov) ScienceAlert, summarizing the new study, said the northern hexagon was first seen by the Voyager probes in 1980 and 1981 and has remained stable through later Hubble and Cassini observations. The new southern feature is a decagon, not a hexagon, and NASA described it as evolving. ### Why are researchers calling it a wave, not a geometric object? (science.org) The September 2 paper described the feature as a decagonal wave, meaning a repeating atmospheric pattern shaped by winds and wave motion in Saturn’s atmosphere. NASA said the decagon encircles the pole within a jet stream, which places it in the category of atmospheric dynamics rather than geology. The agency said the structure spans multiple atmospheric layers. (sciencealert.com) That vertical reach matters because it suggests the pattern is tied to deeper circulation, not just a temporary arrangement of clouds. That reading is an inference from the reported multilayer structure and jet-stream setting. ### What do scientists say is new here? (science.org) The Space Telescope Science Institute called this the first time a large, regular-sided jet pattern has been observed in Saturn’s southern hemisphere. NASA said the decagon appears to have emerged only in recent years and is still strengthening in Hubble data. The paper’s authors, led by Agustin Sanchez-Lavega, reported that ground-based and Hubble images obtained in 2025 revealed the wave clearly. (science.nasa.gov) The study was published as “A decagon wave around Saturn’s south pole” in *Science Advances*. ### What comes next for this Saturn finding? NASA’s September 2 release pointed readers to Hubble imagery and the underlying study, which are now the main public records of the discovery. (stsci.edu) The next step is continued monitoring of Saturn’s south polar atmosphere to see whether the decagon persists, changes shape or strengthens further in future observations. That forward view is based on NASA’s description of the feature as evolving and on the paper’s use of observations spanning 2023 to 2025. (science.org) (science.nasa.gov)