NASA’s Hubble Space Telescope has revealed a giant, evolving 10-sided atmospheric wave encircling Saturn’s south pole, marking the first time astronomers have observed a large, regular-sided jet pattern in the planet’s southern hemisphere, according to NASA and the European Space Agency (ESA).
The newly identified “decagon” bears a striking resemblance to Saturn’s famous hexagon at the planet’s north pole, though researchers say it is also distinctly different in structure, raising the possibility that they are witnessing an entirely new atmospheric phenomenon take shape on the gas giant. The findings have been published in the journal Science Advances.
Saturn South Pole: What Did The Hubble Space Telescope Discover?
According to NASA, the decagon extends through multiple layers of Saturn’s atmosphere and has been confirmed present in Hubble data dating back to 2023. Hubble’s position in orbit above Earth’s atmosphere gives it exceptionally sharp, unsmeared images of the planet across full rotations, allowing researchers to trace the wave’s shape and persistence over successive years in a way ground-based telescopes alone could not achieve.
Saturn South Pole: How Was The Decagon First Spotted?
The discovery was made possible as Saturn’s shifting seasons gradually brought its south pole back into view from Earth, according to the ESA. Lead study author Agustín Sánchez-Lavega, a researcher at the University of the Basque Country in Spain, first noticed a subtle undulating band around the southern pole in 2024 images submitted to the Planetary Virtual Observatory Laboratory, a website run by the university that collects ground-based images of Solar System planets from observers worldwide.
Further imagery gathered in 2025 strengthened the case for a genuine decagon-shaped structure, prompting the team to turn to archival Hubble observations for confirmation.
Saturn South Pole: Why Wasn’t The Decagon Seen Before?
Sánchez-Lavega said scientists had long anticipated finding a southern counterpart to Saturn’s northern hexagon, noting that researchers “have been searching for a counterpart to Saturn’s northern hexagon” in Hubble imagery for decades. He added that NASA’s Cassini spacecraft, which orbited Saturn between 2004 and 2017, had shown no sign of a long-lived formation at the south pole during its mission, making the new discovery all the more unexpected.
Saturn South Pole: How Does It Compare To Saturn’s Famous Northern Hexagon?
Saturn’s northern hexagon has been observed for decades and is known to be a remarkably stable, long-lived feature. By contrast, the newly discovered decagon appears to have emerged only recently, according to NASA scientist Amy Simon of the agency’s Goddard Space Flight Center, who said the timing of its formation was one of the most puzzling aspects of the find, asking “why did it suddenly form now when we haven’t seen one before?”
Saturn South Pole: What Do Scientists Say About The Discovery?
The Hubble observations behind the discovery were gathered as part of the Outer Planet Atmospheres Legacy programme, known as OPAL, which has photographed the solar system’s outer planets annually for more than a decade. Study co-author Michael Wong, of the University of California, Berkeley, said the programme’s long-running design was intended to allow scientists to build up years of comparable data rather than rely on any single observation, noting that many OPAL discoveries only become clear once multiple years of imagery are analysed together.
Saturn South Pole: What Happens Next In The Research?
Researchers say further observations from Hubble, alongside the NASA/ESA/CSA James Webb Space Telescope, along with additional computer modelling, will be needed to understand how the decagon formed, how long it might persist, and how it ultimately compares with the long-lived hexagon at Saturn’s north pole. Scientists say the finding underscores the value of Hubble’s decades-long operational life, which has allowed astronomers to track slow seasonal changes across the solar system that shorter missions would likely have missed entirely.
