Hubble Detects First-Ever Ten-Sided Atmospheric Wave Encircling Saturn's South Pole

Washington, United States – September 2, 2026

NASA's Hubble Space Telescope has detected a vast ten-sided atmospheric wave encircling Saturn's south pole — the first large regular-sided jet pattern ever observed in the planet's southern hemisphere — and the discovery is already reshaping how planetary scientists think about gas-giant meteorology.

The feature appears remarkably similar to Saturn's famous hexagon at its north pole, but is also distinctly different. Its detection, made possible only by Hubble's sharp view from orbit across a full Saturn rotation, suggests scientists may be watching an entirely new atmospheric phenomenon unfold in real time on the ringed planet.

A new shape around an old pole

The decagon is centred near 63 degrees south latitude and was first clearly visible in Hubble imagery from August 2025 that has now been analysed in depth. The wave's apparent position shifts slightly depending on the wavelength of light observed, indicating it is a true atmospheric structure rather than an imaging artefact.

"A 10-sided atmospheric wave encircling Saturn's south pole had not been seen before. Its discovery demonstrates Hubble's continuing power to reveal new atmospheric phenomena even at a target as well-studied as Saturn." — NASA Hubble mission statement, September 2, 2026

The pattern is the southern-hemisphere counterpart to the long-studied north-polar hexagon, a six-sided jet stream that has been locked in place since at least the Voyager flybys of the early 1980s. Until now, no equivalent regular-sided wave had been confirmed in the south.

Why the shape matters

Jets locked into polygonal shapes are rare. Earth's atmosphere does not produce them. Jupiter's banded structure has occasionally hinted at polygonal patterns, but they are short-lived and irregular. Saturn is the only planet where such shapes have been stable for decades — and now it is the only one that has them at both poles.

Atmospheric scientists believe polygonal jets form when deep, fast-moving flows interact with slower surrounding zones. The number of sides reflects how the flow speed varies with latitude, making the geometry a fingerprint of the planet's deep interior. Two distinct polygonal patterns at opposite ends of the same planet imply that whatever process produces them is operating in both hemispheres — but with enough variation to produce different numbers of sides.

How it was captured

Hubble's view from space offers image sharpness and spatial resolution that ground-based telescopes cannot match — particularly for fast-rotating targets like Saturn, where Earth's atmosphere smears detail during long exposures. The new images track Saturn across a full rotation without smearing, allowing the southern pattern to emerge clearly in single-filter and combined colour views.

"Recent observations with the NASA/ESA Hubble Space Telescope have revealed a giant, evolving 10-sided atmospheric wave encircling Saturn's south pole. This discovery marks the first time a large regular-sided jet pattern has been observed in the planet's southern hemisphere." — ESA Hubble press release, September 2, 2026

Why it took so long to notice

The southern hemisphere has been harder to observe in detail because of Saturn's axial tilt and the long polar night that shrouds the south for many Earth years. As Saturn's southern pole has come back into fuller sunlight in recent years, the new wave has become visible — and remained visible — in successive Hubble passes.

That timing is what makes this discovery more than a curiosity. Scientists now have a chance to watch a planetary-scale atmospheric pattern evolve from its first clear detection forward. Past work on the northern hexagon has relied on decades of accumulated data; the southern decagon gives researchers a fresh, instrument-rich record with which to test models from the very beginning.

What comes next

The team behind the discovery — including Agustín Sánchez-Lavega of the University of the Basque Country, Amy Simon of NASA's Goddard Space Flight Center, and Michael Wong of the University of California, Berkeley — plans to use additional Hubble passes and, when available, James Webb Space Telescope observations, to determine whether the decagon is stable or whether it is migrating, intensifying, or fading.

The answer will matter beyond Saturn. Polygonal jet streams are laboratory-scale analogues for how organised flow patterns emerge from chaotic turbulence, and any new example — particularly one that produces a different number of sides from a near-twin process — sharpens the theoretical toolkit used to study atmospheric physics everywhere.

Source: NASA Hubble News Release, September 2, 2026. ESA Hubble Press Release, September 2, 2026. NASA Goddard Space Flight Center feature, September 2, 2026. NASA/ESA Hubble Imaging Archive, August 2025–September 2026.