Hubble Confirms a Strange Ten-Sided Wave Circling Saturn's South Pole

Saturn has surprised astronomers once again. Using the Hubble Space Telescope, an international team has confirmed a ten-sided atmospheric wave circling the planet's south pole, a shape known as a decagon. It gives the ringed world a curious southern counterpart to the famous six-sided hexagon that has swirled over its north pole for decades.

A new shape at the south pole

The feature is described as the first large, regular sided jet pattern ever observed in Saturn's southern hemisphere. Rather than a simple cloud formation, it is a wave that traces out ten distinct sides as it wraps around the pole. The result is a shape that looks almost too geometric to be natural, yet it appears to be a genuine product of the planet's turbulent atmosphere.

For a planet already known for its rings and its northern hexagon, the arrival of a second polygonal structure is remarkable. It suggests that Saturn's poles are more dynamic than a single stable pattern would imply, and that similar processes may be at work at both ends of the planet in different ways.

How it was found

The discovery came together gradually over several years of observation. Hubble data confirmed the presence of the feature in 2023, when the first hints of a ten-vertex outline began to show up in images of the south pole. At that stage the pattern was faint and easy to overlook.

In 2024, ground based observers were the first to identify a subtle undulating band circling the pole, adding weight to the idea that something structured was forming. By 2025, further imagery strengthened the case, with Hubble capturing clearer views on 29 August that year and sharpening the outline into a defined decagon.

A counterpart to the hexagon

Saturn's northern hexagon has been a subject of fascination for around forty years, a stable six-sided jet stream that has persisted through changing seasons. The new decagon resembles it in that both are regular, many sided waves sitting within powerful polar jet streams, but the similarities only go so far.

The crucial difference is behaviour. While the northern hexagon has remained remarkably steady over time, the southern decagon appears to be actively strengthening and developing. That has led researchers to suggest they may be watching a new atmospheric phenomenon take shape in real time, rather than a long settled feature.

What lies beneath

The decagon is not merely a shape painted on the cloud tops. According to the research, it sits within one of Saturn's powerful jet streams and extends vertically through multiple layers of the atmosphere. Its position even shifts slightly depending on the wavelength observed, because different wavelengths probe different altitudes.

That vertical depth matters, because it tells scientists the wave is rooted in the wider circulation of the atmosphere rather than being a shallow, passing effect. Understanding how such structures form and endure could shed light on the fundamental physics that governs the atmospheres of giant planets far beyond our own.

The team behind the discovery

The study was led by Agustin Sanchez-Lavega of the University of the Basque Country in Spain, and published on 3 September 2026 in the journal Science Advances. Key contributors included Amy Simon of NASA's Goddard Space Flight Center and Michael Wong of the University of California, Berkeley.

The effort also drew on the work of amateur astronomers, including Trevor Barry and Jean-Paul Oger, whose observations helped flag the developing pattern. It is a reminder that dedicated skywatchers can still play a meaningful part in professional planetary science. As Amy Simon put it, the team had never seen anything quite like this in Saturn's southern hemisphere, noting that the feature appears to be strengthening.

Why it matters

Beyond its visual appeal, the decagon offers a rare chance to study a planetary weather system while it is still evolving. If astronomers can track how the wave grows or fades in the coming years, they may learn far more about the deep currents that shape Saturn, and about the strange, ordered patterns that can emerge from the chaos of a giant planet's skies.