Introduction
The Saturn south pole has just become the focus of a remarkable planetary science discovery. New observations from NASA’s Hubble Space Telescope show a giant, 10-sided atmospheric wave encircling the planet’s southern polar region, a structure that resembles Saturn’s famous northern hexagon but behaves very differently.
The discovery is particularly interesting because scientists have spent decades looking for a southern counterpart to Saturn’s north-polar hexagon. Now they have one, but it is not the stable mirror image they expected. The newly identified decagon appears to be evolving and moving through Saturn’s atmosphere.
NASA says the feature was confirmed in Hubble observations dating back to 2023, while ground-based observations had already provided hints of its existence. Researchers now want to determine how the structure formed, how long it will survive and what it can teach us about atmospheric dynamics on giant planets.
Background and Context
Saturn is already famous for having one of the strangest weather systems in the solar system.
At its north pole sits a huge six-sided jet-stream pattern known as the Saturn hexagon. The structure was first identified in data from NASA’s Voyager flybys in the 1980s and has remained remarkably persistent over decades of observations. Space.com notes that the northern hexagon is roughly 20,000 miles, or 32,000 kilometers, across.
Scientists have long wondered whether something similar existed at the opposite pole.
There was a problem, though. Saturn’s tilt meant that its southern hemisphere was largely hidden from Earth between 2012 and 2023. That created a long observational gap precisely when astronomers would have liked to monitor the region.
When the south pole became visible again, astronomers started finding something unexpected.
Ground-based observers first noticed a subtle undulating band in images from 2024. Additional observations in 2025 strengthened the case for a polygonal atmospheric structure. Hubble then provided the sharper, space-based observations needed to confirm that the pattern was real.
That is where the story gets especially interesting.
The structure is not a small cloud formation sitting on top of Saturn’s atmosphere. NASA says the wave extends through multiple atmospheric layers, suggesting that it is a vertically extended feature associated with one of Saturn’s powerful jet streams.
Latest Update: Saturn South Pole Decagon Confirmed by Hubble
NASA published its new findings on September 2, 2026, following the publication of the research in Science Advances.
The headline discovery is a 10-sided atmospheric wave surrounding Saturn’s south pole.
NASA describes the structure as the first large, regular-sided jet pattern observed in Saturn’s southern hemisphere. Its overall appearance recalls the famous northern hexagon, but the two features are not identical.
The researchers were able to trace subtle signs of the southern pattern back to 2023 using Hubble’s Outer Planet Atmospheres Legacy, or OPAL, program. That program has been collecting repeated observations of the outer planets for more than a decade.
The value of those repeated observations is enormous.
A single image can show scientists what a planet looks like at one moment. A long-term sequence can show them how an atmospheric system changes.
In this case, that difference allowed researchers to see that the decagon appears to be strengthening.
NASA planetary scientist Amy Simon described the discovery as unlike anything previously seen in Saturn’s southern hemisphere and emphasized that the feature appears to be developing rather than simply persisting unchanged.
How big is Saturn’s new decagon?
It is enormous.
Space.com reports that the decagon is approximately 104,250 miles, or 167,820 kilometers, across. Each of its 10 sides measures roughly 10,425 miles, or 16,782 kilometers.
That puts the feature on a scale that is difficult to visualize from Earth.
The structure is also larger than Saturn’s northern hexagon, according to the measurements reported by Space.com.
But size is not the most important difference.
Movement and stability may be.
The decagon is moving
The northern hexagon is famous partly because it is extraordinarily stable.
The southern decagon is not.
Space.com reports that the decagon takes approximately 800 days to complete a rotation around Saturn. AP describes the feature as migrating eastward at roughly 6 mph, or 10 kilometers per hour.
That movement could provide an important clue about what is driving the phenomenon.
Scientists believe the feature may be a meandering wave trapped within a curved atmospheric jet. Computer simulations using shallow-water models support that possibility.
The researchers are not yet claiming that this completely explains the decagon.
Instead, it gives them a working model to test.
Expert Insights or Analysis
The most fascinating part of the Saturn south pole discovery is not simply that scientists found a geometric shape in the clouds.
It is that they appear to have caught a planetary weather system in the middle of changing.
That distinction matters.
Saturn’s northern hexagon has existed for decades of observations, giving scientists a relatively stable laboratory for studying atmospheric dynamics. The southern decagon offers something different: a system whose evolution can potentially be tracked in real time.
Why does Saturn make polygons?
Atmospheric waves are not unique to Saturn.
Planets with atmospheres can develop disturbances and waves. What makes Saturn unusual is the tendency for some of those atmospheric structures to organize into striking geometric patterns.
The leading explanation involves jet streams.
Saturn’s atmosphere contains powerful bands of rapidly moving gas. When disturbances interact with a jet stream under the right conditions, the flow can develop a stable wave pattern.
For the northern hexagon, previous research has suggested that an eastward jet stream near the pole meanders into a six-sided configuration. Space.com’s reporting indicates that researchers believe the southern decagon could have formed through a related process involving a wave trapped by a curving atmospheric jet.
The key difference may be that the southern structure has not reached the same stable state.
NASA says the decagon changes in appearance depending on wavelength and atmospheric altitude, while its varying characteristics suggest that the feature may still be evolving.
A planetary weather system in slow motion
There is something almost counterintuitive about Saturn’s atmosphere.
Weather on Earth can change within hours or days. Saturn operates on vastly different spatial and temporal scales.
The decagon’s roughly 800-day rotation illustrates just how slowly a planetary-scale atmospheric system can evolve while remaining enormously dynamic.
For researchers, that makes Saturn a natural laboratory.
They cannot recreate an entire gas giant in a laboratory on Earth. But they can observe its atmosphere repeatedly, compare images taken at different wavelengths and build computer models that reproduce aspects of the observed behavior.
The combination of those methods is what turns an unusual image into a scientific investigation.
Broader Implications
What the Saturn south pole could teach us about planetary weather
The new discovery could help scientists better understand how atmospheric circulation works on giant planets.
NASA says researchers want to determine the decagon’s three-dimensional structure, including its clouds, hazes, winds and temperatures. Those measurements could help them develop more sophisticated models of how the feature formed.
That knowledge is useful beyond Saturn.
The fundamental physics governing atmospheric waves, jet streams and large-scale circulation applies across planetary atmospheres, even though the exact conditions vary dramatically from world to world.
Understanding Saturn’s atmosphere can therefore help scientists test broader theories of planetary meteorology.
Hubble’s long-term value
The discovery is also a reminder that some of the most important astronomy does not come from a single spectacular observation.
Hubble’s OPAL program has repeatedly photographed the outer planets for years. That persistence allowed scientists to compare Saturn’s appearance across multiple seasons and identify a feature that would have been much harder to recognize from one image.
The telescope has now been operating for more than three decades.
Its longevity is becoming a scientific advantage.
Instead of simply producing new pictures, Hubble is building an increasingly valuable historical record of how planets change.
The southern hemisphere is finally becoming visible again
Saturn’s changing seasons played a major role in this discovery.
Because of the planet’s axial tilt, its south pole was difficult or impossible to observe from Earth for more than a decade. Once the region became visible again, astronomers had an opportunity to investigate it with modern instruments.
That timing effectively opened a new observational window.
Scientists now have years ahead of them to monitor the decagon as Saturn moves through its seasonal cycle.
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Related History or Comparable Technologies
The obvious comparison is Saturn’s northern hexagon.
The hexagon was first recognized in Voyager data from the early 1980s and has remained visible for decades. Unlike the newly discovered southern structure, it is comparatively stationary.
Scientists have repeatedly used the hexagon to investigate Saturn’s atmospheric circulation.
The decagon now provides a complementary case.
Instead of asking why a long-lived six-sided pattern persists, researchers can ask why a 10-sided structure appears to be forming and changing.
That comparison could be particularly useful.
If the two features arise from related jet-stream physics, scientists may be able to determine which atmospheric conditions favor different polygonal patterns.
If they turn out to be substantially different phenomena, that could be even more interesting.
It would mean Saturn’s atmosphere can generate multiple types of large-scale geometric organization.
Cassini’s missing clue
NASA’s Cassini spacecraft orbited Saturn from 2004 to 2017 and provided an extraordinary amount of information about the planet.
But Cassini did not reveal a long-lived southern polygon comparable to the northern hexagon. NASA says its data showed no indication of such a formation.
That makes the new Hubble observations particularly intriguing.
The decagon may have formed during the period when Saturn’s southern pole was hidden from Earth, potentially between 2017 and 2023. AP reports that researchers suspect the phenomenon may have emerged during that interval.
In other words, scientists may have missed the actual birth of the feature but caught it relatively early in its development.
What Happens Next
The next phase of the research is observation.
NASA says Hubble and the James Webb Space Telescope will be important tools for studying the feature, alongside computer modeling. Scientists want to determine whether the decagon eventually settles into a stable configuration or becomes unstable and disappears.
That makes the coming years unusually valuable.
Researchers can now watch the structure as Saturn’s seasons continue to change.
One major question is whether the decagon will behave more like the northern hexagon or follow a completely different path.
Space.com reports that solar radiation at the decagon’s latitude of roughly 60 degrees south is expected to peak around 2032. Researchers want to know whether increasing solar input will make the feature more stable or help destabilize it.
There are several possibilities.
The decagon could strengthen and become a persistent feature.
It could gradually change shape.
It could break apart.
Or it could transform into another atmospheric pattern entirely.
Each outcome would provide scientists with new information about Saturn’s atmosphere.
Future observations across multiple wavelengths should also help researchers determine how deeply the structure extends and how its winds, clouds and temperatures interact.
Conclusion
The Saturn south pole has delivered something astronomers have been looking for since the discovery of Saturn’s northern hexagon: another giant polygon in the atmosphere of the ringed planet.
But the southern decagon is not simply a second hexagon.
It is larger, it moves, and it appears to be evolving. Hubble observations show that the feature was already present in 2023, while earlier ground-based observations provided additional clues. Scientists now have the opportunity to watch a massive atmospheric structure develop over time.
That may ultimately be more valuable than discovering a perfectly stable counterpart to the northern feature.
A stable weather pattern tells scientists what a planetary atmosphere can sustain.
A changing one can tell them why.
For Saturn, that distinction could turn a strange geometric cloud formation into a window on the physics governing atmospheres across the solar system.
And for Hubble, it is another example of why decades of continuous observation can reveal things that a single snapshot never could.
FAQ
1. What was discovered at Saturn’s south pole?
Scientists discovered a giant 10-sided atmospheric wave, known as a decagon, encircling Saturn’s south pole. Hubble observations confirmed the feature and showed that it extends through multiple atmospheric layers.
2. How big is the Saturn south pole decagon?
The decagon is approximately 104,250 miles, or 167,820 kilometers, wide, according to Space.com. Each side is roughly 10,425 miles long.
3. Is Saturn’s southern decagon the same as its northern hexagon?
No. Both are polygonal atmospheric structures associated with jet streams, but the northern hexagon is much more stable. The southern decagon appears to move and may still be evolving.
4. When did scientists first see the Saturn south pole decagon?
Hubble observations confirmed the structure back to 2023. Ground-based astronomers had identified hints of the feature in observations made later, including images from 2024 and 2025.
5. How fast does Saturn’s decagon move?
Space.com reports that the decagon takes approximately 800 days to complete a rotation around Saturn. AP describes its eastward migration at roughly 6 mph, or 10 kilometers per hour.
6. Why does Saturn have geometric weather patterns?
Scientists believe powerful jet streams and atmospheric waves can interact in ways that produce polygonal patterns. Computer simulations suggest the southern decagon may be a meandering wave trapped by a curved atmospheric jet.
7. Could the Saturn south pole decagon disappear?
Yes. Scientists do not yet know whether it will become a long-lived stable structure or eventually become unstable and break apart. Continued observations are needed to determine its fate.
8. What will scientists study next?
Researchers plan to continue observing the decagon with Hubble and James Webb while using computer models to investigate its formation, evolution, atmospheric layers, winds, clouds and temperatures.
Sources & References
- NASA Science, “NASA’s Hubble Tracks New Decagon Encircling Saturn’s South Pole”
Read the NASA report - Space.com, “Astronomers discover mysterious 10-sided cloud structure at Saturn’s south pole”
Read the Space.com report - Associated Press, “Scientists find a churning decagon over Saturn’s south pole”
Read the AP report - Science Advances, research on Saturn’s southern atmospheric decagon
The research was published in Science Advances on September 2, 2026.
