Saturn's South Pole Has a Giant Decagon: What Hubble Found

Saturn was already famous for one oddity: a giant hexagon — a nearly perfect six-sided figure — spinning over its north pole. Now, in early September 2026, astronomers using the Hubble Space Telescope announced its unexpected counterpart at the other end of the planet: a decagon, a ten-sided atmospheric pattern, at the south pole.

Giant Polygons at the Poles

In nature it's rare to find such regular geometric figures, let alone ones the size of a planet. Saturn's north-pole hexagon has been there for more than 40 years: the Voyager probes saw it in the 1980s and the Cassini mission tracked it through 2017. It forms because a jet stream — a fast wind looping around the pole — meanders so evenly that it traces straight sides and corners, like an enormous polygon made of clouds.

What's new is that the south pole, which for decades showed nothing like it, now has its own version: a decagon. It isn't an identical mirror of the north — it has ten sides instead of six — but a figure with its own character.

What Makes It So Unusual

Three things stand out, and you don't need the fine-grained physics to see them:

• It showed up recently. Hubble data show the first hints only around 2023, and ground-based observers noticed an undulating band in 2024. It's rare to watch a giant atmospheric pattern being born — with this one, we can.
• It's strengthening. Instead of fading, it sharpens over time, giving the uncommon chance to follow its development year by year.
• It has a different number of sides. Ten, not six. That both poles have polygons, but different ones, is exactly what intrigues scientists.

The wave also isn't just a surface cloud shape: it extends through several layers of the atmosphere, within one of Saturn's jet streams. Adjust the number of sides in the widget to compare the hexagon and the decagon as geometric figures.

The Takeaway

The south-pole decagon makes Saturn the only known planet with a large polygon at each pole — and different ones at that. Astronomers will keep watching it with Hubble and James Webb to understand why it formed now and whether it will become as stable and long-lived as its northern neighbor. For now, it's a rare chance to see a giant phenomenon while it's still taking shape.

And the geometry of those figures is yours to explore. A regular polygon calculator lets you see how the angles change between a hexagon and a decagon, and why more sides means more "open" corners.

Information based on observations from the Hubble Space Telescope (NASA/ESA), as part of the OPAL program, and on the study published in September 2026 in Science Advances, led by Agustín Sánchez-Lavega (University of the Basque Country). Informational and educational; the atmospheric description is kept deliberately simple.