Astronomers finally spot what Saturn’s South Pole was hiding: A massive 10-sided atmospheric wave that scientists still can’t explain

Saturn has spent decades guarding one of the strangest secrets in the Solar System: a giant geometric pattern embedded in its atmosphere.

The planet’s northern hexagon has fascinated scientists since the Voyager spacecraft first revealed it in the early 1980s. But now, astronomers have found something just as surprising at the opposite end of Saturn.

A huge 10-sided atmospheric wave, or decagon, is circling the planet’s south polar region.


The discovery is forcing scientists to reconsider the idea that Saturn’s famous hexagon is a one-off atmospheric oddity. More importantly, the newly detected structure appears to be evolving, giving researchers an unusual opportunity to watch a planetary weather system change over time.

Saturn’s South Pole reveals an unexpected shape

The decagon was identified through observations made as Saturn’s southern hemisphere gradually became easier to see from Earth.

Researchers examining images from the NASA/ESA Hubble Space Telescope, together with observations from amateur astronomers and ground-based instruments, found evidence of the unusual pattern dating back to 2023. Earlier observations from the Cassini mission, which studied Saturn between 2004 and 2017, had not revealed a comparable structure.

That absence is significant.

It suggests the feature may have developed relatively recently, possibly during the period when Saturn’s south pole was poorly positioned for observation from Earth.

By 2024 and 2025, however, the pattern had become much clearer.

What astronomers saw was not a conventional storm shaped like a polygon. Instead, the decagon appears to be a large atmospheric wave embedded within one of Saturn’s powerful jet streams.

A giant atmospheric wave, not a surface feature

Saturn has no solid surface like Earth, so the strange shape is part of its constantly moving atmosphere.

The newly identified wave sits around the southern polar region and is associated with an eastward-moving jet stream whose winds reach roughly 400 kilometres per hour. The decagon itself drifts far more slowly, moving at around 10 kilometres per hour relative to Saturn’s rotation.

Observations at different wavelengths have made the discovery even more intriguing.

Because different wavelengths allow astronomers to examine different atmospheric levels, researchers found evidence that the decagonal pattern extends through multiple layers of clouds and haze.

That means the phenomenon is not simply a peculiar outline appearing in one layer of Saturn’s clouds. It has a vertical structure within the atmosphere.

Scientists still do not know how deeply rooted it is.

Why does Saturn keep making geometric patterns?

The discovery becomes particularly interesting when compared with Saturn’s northern hexagon.

That six-sided atmospheric wave has survived for more than four decades and appears remarkably stable. The newly found southern structure, by contrast, looks less mature and less uniform.

Some of its corners are much clearer than others, suggesting that the decagon could still be developing. Its vertices also undergo an oscillating motion with a period of about 32 days, something not observed in the northern hexagon.

The contrast raises a fundamental question: why does Saturn’s atmosphere produce polygons at all?

Atmospheric waves and disturbances are common on planets with atmospheres. But large, remarkably regular polygonal structures appear to be an unusual feature of Saturn.

The discovery therefore offers scientists a second example with which to investigate the physics behind the phenomenon.

A nearby storm could hold a clue

One possible explanation lies close to the newly discovered decagon.

Researchers have identified a large high-pressure vortex near the southern polygon. The storm, roughly 4,000 kilometres across, could potentially influence the atmospheric wave around it.

The decagon is particularly pronounced on the side closest to this vortex and becomes less distinct on the opposite side.

That makes the nearby storm an intriguing suspect.

However, computer simulations have not yet produced a convincing recreation of the observed structure. The idea therefore remains a possibility rather than a confirmed explanation.

There is another reason scientists are cautious.

When Saturn’s northern hexagon was first discovered, researchers also considered whether a nearby atmospheric vortex might be responsible. That vortex later disappeared, while the hexagon remained.

So even if the southern storm helped create the decagon, it may not be the whole story.

The hexagon and decagon are not twins

At first glance, the two structures may seem like mirror images: one polygon at Saturn’s north pole and another at its south.

But closer inspection shows important differences.

The northern hexagon is positioned farther toward the pole and has remained remarkably persistent. The southern decagon sits at a lower latitude and appears to be less stable.

Even their motion differs.

The northern structure is essentially stationary relative to Saturn’s rotation, while the decagon slowly moves eastward. Its individual vertices also display an oscillating movement.

These differences could provide important clues about the winds and atmospheric conditions responsible for forming each pattern.

Saturn’s changing seasons could reveal the answer

Timing may now work in astronomers’ favour.

Saturn takes about 29.5 Earth years to orbit the Sun, meaning its seasons are extremely long. Each season lasts roughly seven and a half Earth years.

The planet’s southern hemisphere is currently moving from spring toward summer, bringing increasing sunlight to the region where the decagon has appeared.

That gives researchers an opportunity to watch the structure as Saturn’s seasonal conditions change.

Will the decagon become more sharply defined?

Will it weaken and disappear?

Or could it become as stable as the famous northern hexagon?

Those are among the questions scientists now hope to answer.

Astronomers can watch the mystery unfold

The most valuable aspect of the discovery may be that scientists did not find a decades-old structure whose formation was missed.

Instead, they appear to have caught a relatively new atmospheric phenomenon while it is still evolving.

Future Hubble observations, ground-based telescope measurements and continued observations by amateur astronomers could reveal how its shape, speed and atmospheric environment change.

Researchers will also be able to compare the decagon with Saturn’s long-lived hexagon and with polygonal atmospheric structures seen in other gas giants.

For now, however, the central mystery remains unsolved.

Saturn has demonstrated that its atmosphere can produce enormous geometric waves at both poles. What turns turbulent planetary weather into such precise polygons is still something scientists cannot fully explain.

And as the southern pole becomes increasingly visible, astronomers may finally get the long-term observations needed to discover how Saturn makes them.