Researchers show 10-sided structure on Saturn

Saturn’s newly reported “10-sided structure” is not a solid object and not a ring feature. NASA and ESA said on September 2 that Hubble observations revealed a giant, evolving decagonal atmospheric wave encircling Saturn’s south pole, the first large regular-sided jet pattern seen in the planet’s southern hemisphere. (esa.int) The finding was published in Science Advances by a team led by Agustín Sánchez-Lavega of the University of the Basque Country. (science.org) The feature matters in part because Saturn’s north pole already hosts the planet’s better-known hexagon. The new southern pattern suggests polygonal waves may not be unique to one pole, though researchers said the decagon appears younger and still developing. (esa.int) ### So what exactly did researchers find? Hubble data show a 10-sided atmospheric wave wrapped around Saturn’s south polar region. Science Advances described the feature as a decagonal wave at planetographic latitudes of roughly 58°S to 63°S, embedded in a jet stream rather than standing apart from the surrounding atmosphere. (esa.int) ESA said the wave extends through multiple layers of Saturn’s atmosphere. That point comes from observations at different wavelengths, which trace different altitudes and showed the pattern persisting across more than one atmospheric level. (esa.int) ### Is this the same as Saturn’s famous hexagon? Saturn’s northern hexagon was first seen in Voyager images in 1980 and 1981 and has remained visible for more than 40 years, according to ScienceAlert’s report citing the research team and NASA’s account of the new study. The southern decagon is similar in being a polygonal wave near a pole, but researchers said it is not a simple mirror image. (science.org) Amy Simon, a study co-author and OPAL principal investigator at NASA’s Goddard Space Flight Center, said the northern hexagon “has been there every time we’ve looked for more than 40 years,” while the southern feature “appears to be strengthening.” ESA said that gives scientists a chance to watch a giant atmospheric pattern develop rather than study only a long-stable one. (esa.int) ### When did it appear? Researchers pieced the case together from several years of observations. ESA said Hubble images dating back to 2023 showed subtle hints before the pattern became clearer, while ground-based images first drew attention to an undulating band in 2024 and strengthened the case in 2025. (sciencealert.com) Agustín Sánchez-Lavega and amateur astronomers Trevor Barry and Jean-Paul Oger were among those who identified the feature in ground-based observations, according to ESA. Sánchez-Lavega said the team had been searching for a southern counterpart to the northern hexagon in Hubble images since 1990. (esa.int) ### Why are there wavelength maps and coordinates in the images? Different wavelengths let researchers sample different heights in Saturn’s atmosphere. NASA and ESA said the decagon’s apparent position shifts slightly between wavelength views because each filter probes a different altitude, helping researchers test whether the pattern is shallow or vertically extended. (esa.int) Science Advances and the supplementary material also provide the measured latitude range and additional observing context, including infrared imagery from 2025. That is why the public-facing graphics are paired with coordinates and filter information rather than a single “pretty picture.” (esa.int) ### What happens next? The paper is already out in Science Advances, and the image set comes from Hubble’s OPAL program, which has photographed the outer planets annually for more than a decade. Future OPAL observations and additional ground-based imaging will show whether the decagon keeps strengthening, shifts in latitude, or settles into a long-lived pattern like the northern hexagon. (esa.int) (science.org)