A mysterious giant 10-sided cloud pattern has recently formed around Saturn’s south pole, according to a new study. This new “decagon” joins the strange and colossal hexagon seen for decades at Saturn’s north pole. The Saturn hexagon, a pattern of clouds about 20,000 miles (32,000 kilometers) wide, was first discovered in 1988 by scientists reviewing data from NASA’s Voyager flybys of Saturn in 1980 and 1981. Despite decades of observations, no similar structure was seen anywhere else on Saturn—until now, when scientists have discovered an even larger structure. on Saturn. The newly discovered decagon measures approximately 104,250 miles. (167,820 kilometers) wide, and each of its 10 sides measures approximately 10,425 miles (16,782 km) long. “This is a very unusual atmospheric phenomenon that is helping us advance our understanding of meteorology in general,” the study’s lead author, Agustín Sánchez-Lavega, a planetary scientist at the University of the Basque Country in Bilbao, Spain, told Space.com. “This tells us that the hexagon is not a unique, singular feature, as previously thought.” In the new study, researchers examined recent images of Saturn captured with NASA’s Hubble Space Telescope. The way Saturn’s axis is tilted meant that the ringed planet’s southern hemisphere was not visible from Earth between 2012 and 2023. Hubble images from 2023 revealed the decagon to scientists for the first time. “It was certainly a surprise,” Sánchez-Lavega said. Since the hexagon was discovered in the north of Saturn, he and his colleagues had investigated photographs of Saturn “to see if there was a polygonal formation in the south. And there was no sign of it.” You might like The Decagon Moves Slowly. “It takes about 800 days to complete one rotation around Saturn,” Sánchez-Lavega said. Previous research suggested that Saturn’s hexagon is the result of an eastward jet within its atmosphere that flows in a curved path near the ringed planet’s north pole. Small disturbances in the jet (the kind you would expect when colliding with other air currents) caused it to take on a hexagonal shape. This colorful space wallpaper from NASA’s Cassini mission is the highest resolution view of the unique six-sided jet stream at Saturn’s north pole known as the hexagon. Image obtained on December 10, 2012 and published on December 4, 2013. (Image credit: NASA/JPL-Caltech/SSI/Hampton) Similarly, experiments that Sánchez-Lavega and his colleagues performed with computer simulations of currents in shallow water suggest that the decagon formed due to a meandering wave trapped by a curved atmospheric jet. Unlike the hexagon, whose sides and tips have remained equally dark for decades, the decagon varies in darkness depending on its characteristics. This could mean that it may still be evolving. “We need to understand how the decagon evolves; in other words, whether in the coming years it will become unstable and fragment or, on the contrary, become more stable and robust as solar radiation increases, which will peak at its latitude of about 60 degrees south in 2032,” Sánchez-Lavega said. Scientists also want to gain a more detailed understanding of the three-dimensional structure of the decagon’s clouds, mists and winds. and temperatures. This will help them “develop more advanced models of their training,” Sánchez-Lavega said. The scientists detailed their findings Sept. 2 in the journal Science Advances.
