NASA’s Hubble Tracks New Decagon Encircling Saturn’s South Pole

NASA’s Hubble Space Telescope has revealed a remarkable new mystery in Saturn’s atmosphere: a giant, evolving 10-sided atmospheric wave, or decagon, encircling the planet’s south pole.

The discovery is significant because Saturn was already famous for its extraordinary six-sided atmospheric pattern at the north pole. Now, astronomers have identified a completely different polygonal structure in the southern hemisphere—one that appears to have emerged and strengthened over recent years.

The newly observed feature is not a solid object or an unusual cloud shaped like a geometric symbol. It is a large-scale atmospheric wave embedded within one of Saturn’s powerful jet streams and extending through multiple layers of the planet’s atmosphere.

What Did NASA’s Hubble Discover?

The Saturn south pole decagon discovery comes from years of observations made with the NASA/ESA Hubble Space Telescope.

Researchers traced signs of the unusual structure back to 2023. At first, the feature appeared as a subtle undulating band, but subsequent observations made the 10-sided pattern increasingly clear. NASA says this is the first time astronomers have observed a large, regular-sided jet pattern in Saturn’s southern hemisphere.

The wave is centred at roughly 63 degrees south latitude and sits within one of Saturn’s powerful atmospheric jet streams. Observations at different wavelengths show the feature at different altitudes, indicating that the decagon is not confined to a single layer of visible clouds.

That makes the discovery scientifically more important than simply finding an unusual shape in an image. Astronomers are studying a vertically extended atmospheric structure inside one of the Solar System’s most complex planetary weather systems.

Saturn’s Famous Hexagon Now Has a Southern Counterpart

For decades, Saturn’s north pole has fascinated scientists because of its famous hexagon—a six-sided atmospheric pattern associated with a powerful jet stream.

The newly discovered southern structure is similar enough to invite comparison, but it is also fundamentally different.

Instead of six sides, the new feature has 10.

NASA and ESA say the decagon may represent a new atmospheric phenomenon developing on the gas giant. The contrast between Saturn’s northern hexagon and southern decagon could provide valuable information about how differences in atmospheric conditions can produce dramatically different large-scale wave patterns.

The north-polar hexagon has been known for decades, while the southern decagon appears to be a comparatively recent and evolving feature. Hubble observations show that the structure was present by 2023 and became increasingly pronounced in later observations.

Why Does Saturn Produce Geometric Atmospheric Patterns?

Scientists do not yet have a complete explanation for every aspect of Saturn’s new decagon, but its location inside a powerful jet stream provides an important clue.

Planetary atmospheres contain moving gases, temperature differences and powerful winds. On rapidly rotating planets such as Saturn, these forces can interact to create large-scale waves and vortices.

Several factors can influence such atmospheric structures, including:

• The speed and direction of jet streams
• Differences in wind speeds at different altitudes
• Temperature variations
• Atmospheric depth and composition
• Saturn’s rapid rotation

A change in these conditions can alter the behaviour of atmospheric waves.

This may help explain why Saturn can have a six-sided structure at one pole and a 10-sided structure at the other. However, scientists are still investigating exactly why the southern atmospheric wave developed into a decagon.

The important distinction is between what has been observed and what remains uncertain. The 10-sided atmospheric wave itself is confirmed; the complete physical explanation for why it formed is still being studied.

Why Hubble Was Crucial to the Discovery

The Hubble Space Telescope played a key role because it can observe Saturn repeatedly with high spatial resolution.

Researchers combined observations collected over several years through Hubble’s Outer Planet Atmospheres Legacy (OPAL) programme, which has monitored the outer planets annually for more than a decade. Ground-based observations also provided additional evidence as the pattern became more distinct.

The discovery also demonstrates the value of long-term planetary monitoring.

A single image might capture an unusual atmospheric feature, but repeated observations allow scientists to determine whether a structure is temporary, evolving or potentially long-lasting.

In this case, comparing observations from different years helped researchers identify the gradual development of the decagon.

What Makes the Southern Decagon Different?

One of the most intriguing aspects of the discovery is that the feature appears to be evolving.

NASA describes it as a giant, evolving 10-sided atmospheric wave rather than a fully understood permanent structure. The observations suggest astronomers may be watching a new phenomenon develop in Saturn’s atmosphere.

The decagon also appears different when viewed at different wavelengths of light. This happens because different wavelengths can probe different atmospheric altitudes.

As a result, the apparent position of the wave shifts slightly depending on how Saturn is observed. That provides researchers with a way to study the structure in three dimensions and investigate how it behaves through multiple atmospheric layers.

The Bigger Scientific Importance of the Discovery

Saturn is effectively a natural laboratory for studying atmospheric physics on giant planets.

Unlike Earth, Saturn has no conventional solid surface beneath its visible cloud layers. Its atmosphere contains powerful jet streams, massive storms and complex interactions between gases at different depths.

Understanding the decagon could therefore help scientists improve models of atmospheric behaviour not only on Saturn but also on other giant planets.

Jupiter, for example, has its own complex polar storm systems. Comparing atmospheric patterns across different worlds may help researchers understand how planetary rotation, internal heat and atmospheric circulation interact.

The newly discovered decagon is especially valuable because scientists may be able to monitor its evolution from an early stage rather than studying only a long-established structure.

The research findings were published in the journal Science Advances, while NASA and ESA released the new Hubble observations on September 2, 2026.

What Will Astronomers Watch Next?

The biggest unanswered question is whether Saturn’s decagon will survive and become a long-lasting atmospheric feature.

Future observations could show several possible outcomes:

• The 10-sided pattern could become more stable.
• Its shape could change as atmospheric conditions evolve.
• The structure could weaken or eventually disappear.
• Scientists could discover additional links between the southern decagon and Saturn’s northern hexagon.

At present, these remain possibilities rather than confirmed predictions.

Continued monitoring will be particularly important because Saturn’s atmosphere changes over time, and the planet’s viewing geometry from Earth also changes. Each new observation could provide additional information about the decagon’s structure, movement and behaviour.

A New Mystery at Saturn’s South Pole

NASA’s discovery of a new decagon encircling Saturn’s south pole has added another extraordinary chapter to the study of the Solar System’s giant planets.

What is confirmed is remarkable enough: a giant 10-sided atmospheric wave has emerged within Saturn’s southern jet stream, extends through multiple layers of the atmosphere and has become increasingly distinct in observations since 2023.

What remains unknown may be even more interesting. Scientists are still working to understand exactly why the wave formed with 10 sides and whether it will become a long-lasting feature like Saturn’s famous northern hexagon.

For now, the decagon offers astronomers a rare opportunity to watch a major atmospheric phenomenon evolve on another world.

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