For decades Saturn has worn a six-sided crown at its north pole. Now scientists have spotted a strange ten-sided pattern emerging in the south, and it is still growing.
Saturn has long been famous for a peculiar quirk of its weather, a giant six-sided pattern that has crowned its north pole for as long as astronomers have been able to look. Now the ringed planet has produced a fresh surprise at the opposite end. Scientists have identified a striking ten-sided shape taking form around its south pole, and remarkably, it appears to still be growing.
A shape that should not be there
The newly described feature is a decagon, a ten-sided atmospheric wave encircling Saturn's southern pole. According to the research, it is the first time such a large and regular many-sided jet pattern has been clearly observed in the planet's southern hemisphere. That alone makes it a notable addition to the catalogue of the solar system's strangest weather phenomena.
What captured researchers' attention was not just the shape itself but its timing. Rather than being a long-standing fixture that had simply gone unnoticed, the decagon seems to be a genuinely recent arrival. That gives scientists something they rarely get, the chance to study one of these vast polar patterns as it actually develops rather than long after it has settled in.
How the shape was found
The discovery grew out of a collaboration between professional and amateur skywatchers. According to reports, lead researcher Agustin Sanchez-Lavega of the University of the Basque Country in Spain, working with amateur astronomers including Trevor Barry and Jean-Paul Oger, first noticed a faint, wavy band near Saturn's south pole in imagery captured in 2024 through the Planetary Virtual Observatory Laboratory.
To confirm that the fleeting hint was real, the team turned to one of the most powerful tools in astronomy. Observations from NASA's Hubble Space Telescope, whose superior resolution proved decisive, showed that the pattern could be traced back to at least 2023. The findings were published on September 2, 2026, in the journal Science Advances, giving the decagon its formal scientific debut.
That partnership is worth pausing on, because it says something about modern astronomy. Dedicated amateurs with backyard equipment routinely capture the outer planets night after night, building a running record that professionals can mine for exactly this kind of subtle change. Their patient contributions helped flag a feature that might otherwise have slipped past, a reminder that meaningful discoveries are not confined to major institutions alone.
A counterpart to the famous hexagon
Inevitably, the new feature invites comparison with Saturn's celebrated northern hexagon. That six-sided structure has been present every time astronomers have checked for more than forty years, a picture of stability. The southern decagon, by contrast, looks distinctly different, appearing to strengthen and evolve rather than sit unchanged, which is exactly what makes it so scientifically valuable.
Amy Simon of NASA's Goddard Space Flight Center, who helps lead the long-running programme that monitors the outer planets, highlighted precisely this point. The fact that the feature appears to be strengthening, she noted, offers researchers the rare opportunity to watch a giant atmospheric pattern take shape in something close to real time, a gift for anyone trying to understand how they form.
More than a passing cloud
Crucially, this is no shallow smudge in the upper haze. According to the study, the decagon extends through multiple layers of Saturn's atmosphere and sits within a powerful jet stream, suggesting it is a deeply rooted structure rather than a superficial trick of the light. That depth hints at strong, organised winds shaping the gas giant's polar regions in ways still not fully understood.
Understanding why these polygonal jets appear at all remains one of the open puzzles of planetary science. On Earth, atmospheric flows rarely lock into such neat geometric shapes, so seeing them on Saturn offers a natural laboratory for testing ideas about how rotating fluids and fast winds interact. Each new example, especially a changing one, adds a valuable data point to that long investigation.
What comes next
The story is far from over. Researchers including Michael Wong of the University of California, Berkeley, are among those studying the phenomenon, and further observations are planned using NASA's James Webb Space Telescope to probe the feature in greater detail. Continued monitoring should reveal whether the decagon keeps strengthening, stabilises like its northern cousin, or fades away entirely.
For now, the emerging shape stands as a reminder that even a planet studied for centuries can still astonish us. With patient eyes on the ground and powerful telescopes in space working together, astronomers are catching Saturn in the act of rearranging its own skies. It is a rare front-row seat to a slow, silent piece of cosmic architecture unfolding hundreds of millions of miles away.
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