Astronomers have identified a ten-sided atmospheric structure swirling above Saturn’s South Pole, a geometric phenomenon never before observed on the gas giant or any other planet.
The discovery, published Wednesday in Science Advances, reveals a decagonal wave pattern that emerged while the planet’s southern hemisphere spent more than a decade shrouded in winter darkness. Images captured in both 2024 and 2025 confirmed the feature’s existence, according to researchers at the University of Leicester in the UK.
Professor Leigh Fletcher, 47, a co-author from the university’s School of Physics and Astronomy, credited amateur skywatchers with first spotting clues to the mystery. In a statement accompanying the publication, he highlighted their crucial role in the breakthrough.
“What’s really exciting about this work is the involvement of amateur observers with their backyard telescopes, sharing their images online, and searching Saturn’s clouds for new discoveries. It was their data that first hinted something exciting was going on,” Fletcher wrote.
He added that the timing of the discovery carries special significance for researchers tracking Saturn’s seasonal cycles. “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 stunning new feature around the South Pole.”
The finding creates an intriguing asymmetry in Saturn’s polar geometry. Voyager 1 and Voyager 2 first photographed a hexagonal wave encircling the north pole during flybys in 1980 and 1981, and that six-sided structure has persisted for more than four decades. Yet no corresponding feature had ever been detected in the southern hemisphere until these recent observations.
Fletcher raised pointed questions about what happens next as Saturn continues its orbital progression. “The hexagon itself is now hidden from view, as the North Pole disappears into autumn and winter. Who knows whether that will still be there next time we can look? And how long this new decagon will hang around for?” he wrote.
Agustín Sánchez-Lavega of Universidad del País Vasco EHU, who led the study, emphasized that the discovery opens more avenues of investigation than it resolves. The planetary scientist framed the decagon as part of a broader puzzle about geometric atmospheric formations across the solar system’s gas giants.
“This research raises many fundamental questions about atmospheric phenomena on gas giants. Why is Saturn the only planet to form this type of polygonal waves? Is the phenomenon in any way related to the 5- and 8-sided polygonal arrangement of the cyclones surrounding Jupiter’s poles?” Sánchez-Lavega said in the publication.
He continued by outlining the observational path forward. “Further observations over the coming years, as visibility of the planet’s southern hemisphere gradually improves, will help to characterise it and develop advanced models that will enable us to solve this intriguing atmospheric mystery.”
The hexagonal north polar structure has remained one of planetary science’s most enduring curiosities since its detection, stretching approximately 25,000 kilometers across with sides each longer than Earth’s diameter. Its persistence suggested deep atmospheric dynamics at Saturn’s poles, yet the absence of any southern counterpart left theories incomplete. The newly revealed decagon now offers researchers a second data point for understanding how these polygonal waves form and survive.
Unlike Jupiter’s polar cyclones, which organize into polygonal patterns of five and eight storms respectively at its north and south poles, Saturn’s features appear as continuous wave structures rather than discrete rotating systems. This distinction has fueled debate about whether similar physical mechanisms drive both phenomena or if Saturn represents a unique case in planetary atmospherics.
The research team noted that improved visibility from Earth in recent years enabled both professional and amateur astronomers to track the southern feature’s development as Saturn’s tilt exposed more of its south polar region to observation.