NASA Hubble Discovers Giant 10-Sided Shape on Saturn’s South Pole: What Is the Mysterious Decagon?

Image Credit: NASA, ESA, STScI, Agustín Sánchez-Lavega (UPV), Amy Simon (NASA-GSFC), Michael Wong (UC Berkeley); Image Processing: Alyssa Pagan

NASA’s Hubble Space Telescope has revealed a giant, evolving 10-sided atmospheric wave around Saturn’s south pole, giving scientists a rare opportunity to watch a large planetary weather pattern develop.

Saturn is famous for its extraordinary atmosphere, including the long-lived hexagonal jet stream surrounding its north pole. Now, astronomers have discovered something remarkably different in the planet’s southern hemisphere: a large 10-sided atmospheric wave, or decagon, encircling Saturn’s south pole.

The feature was identified by combining observations from ground-based telescopes with several years of NASA Hubble Space Telescope observations. Researchers found evidence that the pattern was already present in 2023 and has become increasingly distinct over time. The results were published in Science Advances on September 2, 2026.

What Did NASA Discover on Saturn?

Recent Hubble observations show a large, regular-sided atmospheric wave surrounding Saturn’s south pole.

The structure is embedded within one of Saturn’s powerful jet streams and appears as a 10-sided pattern when viewed around the planet’s southern polar region.

NASA describes the feature as a giant, evolving atmospheric wave. Scientists say this is the first time a large, regular-sided jet pattern of this type has been observed in Saturn’s southern hemisphere.

Unlike a solid object or physical structure on Saturn’s surface, the decagon is an atmospheric phenomenon created by the movement and interaction of gases in the planet’s atmosphere.

What Is Saturn’s 10-Sided Pattern?

A 10-sided polygon is called a decagon.

In Saturn’s case, the term describes the shape of an atmospheric wave surrounding the planet’s south pole. The wave is not a permanent solid formation. Instead, it is associated with one of Saturn’s powerful atmospheric jet streams.

Hubble observations show that the feature extends through multiple layers of Saturn’s atmosphere, suggesting that it is more than a pattern confined to a single layer of clouds.

The feature is centered around approximately 63 degrees south latitude. Its apparent position changes slightly depending on the wavelength used for observation because different wavelengths probe different altitudes in Saturn’s atmosphere.

How Was the Saturn Decagon Discovered?

The discovery was built from observations collected over several years.

Researchers first noticed subtle signs of an unusual undulating band in ground-based images of Saturn. According to NASA, Agustín Sánchez-Lavega and amateur astronomers Trevor Barry and Jean-Paul Oger identified the feature in observations from 2024.

Additional ground-based observations in 2025 provided stronger evidence of the developing pattern.

Hubble then provided much sharper observations from space, allowing researchers to examine the structure in greater detail and confirm that it was already present in Hubble observations dating back to 2023.

Why Hubble Was Important

Observing Saturn from Earth can be challenging because Earth’s atmosphere distorts astronomical images.

Hubble operates above Earth’s atmosphere, allowing it to obtain much sharper views of Saturn. Its observations can also examine different wavelengths of light, providing information about different levels of the planet’s atmosphere.

The Hubble observations used in this research were part of the Outer Planet Atmospheres Legacy, or OPAL, program, which has monitored the outer planets for more than a decade.

Long-term observations like these are particularly valuable because atmospheric features can change over periods of years rather than hours or days.

Saturn Already Has a Famous Hexagon

Saturn’s northern hemisphere is already home to one of the most unusual atmospheric structures in the Solar System.

A persistent six-sided jet-stream pattern, commonly called Saturn’s hexagon, surrounds the planet’s north pole.

NASA says the northern hexagon was first noticed in images from the Voyager spacecraft in the early 1980s and was later studied in greater detail by the Cassini mission.

The feature spans roughly 20,000 miles (30,000 kilometers) across and is associated with extremely powerful winds.

For decades, scientists had searched for a comparable regular-sided atmospheric pattern at Saturn’s south pole.

They did not find evidence of one during the Cassini mission, which orbited Saturn from 2004 to 2017.

The new Hubble observations have now changed that picture.

Saturn’s Decagon Is Different From Its Northern Hexagon

Although the newly discovered southern pattern may appear similar to Saturn’s famous northern hexagon, scientists emphasize that the two features are not identical.

The northern hexagon has remained remarkably stable for more than four decades.

The southern decagon, in contrast, appears to be strengthening and becoming more clearly defined.

That difference makes the discovery especially interesting.

Scientists may now have an opportunity to watch a large atmospheric pattern develop instead of studying one that has already been stable for decades.

Scientists May Be Watching a New Atmospheric Phenomenon Develop

One of the biggest scientific questions is why the decagon has appeared and changed over time.

NASA says researchers found subtle hints of the structure beginning to emerge in observations dating back to 2023.

By comparing observations from different years, scientists found that the pattern became increasingly distinct.

This gives researchers something unusual: a chance to study the development of a large-scale atmospheric wave on another planet in real time.

The team will continue monitoring Saturn to determine whether the structure eventually becomes stable or continues to evolve.

What Causes Saturn’s Decagon?

Scientists do not yet have a complete explanation for why the southern decagon formed.

The feature is located within one of Saturn’s powerful jet streams, so researchers are investigating how the dynamics of the jet stream could produce the regular 10-sided wave.

The underlying research describes Saturn’s northern hexagon as a unique, long-lived atmospheric wave associated with an intense eastward jet.

The newly observed southern wave provides scientists with an important comparison that could help improve their understanding of atmospheric dynamics on giant planets.

However, the exact mechanism responsible for the southern decagon remains an active area of research.

Why Does Saturn Have Geometric Atmospheric Patterns?

Saturn is a gas giant with a complex atmosphere containing powerful winds and jet streams.

These atmospheric flows can create enormous waves and structures that look surprisingly geometric when viewed from above.

Saturn’s northern hexagon is the best-known example.

The discovery of a southern decagon suggests that Saturn’s atmosphere may be capable of producing different large-scale patterns under changing conditions.

Studying these structures can help scientists understand how atmospheric circulation works on giant planets throughout the Solar System.

What Happens Next?

Scientists plan to continue observing Saturn to determine how the decagon changes.

One major question is whether the structure will eventually settle into a long-lived configuration like the northern hexagon.

Another question is what caused the southern wave to appear after decades without a clearly identified counterpart.

Continued observations at different wavelengths will allow researchers to examine the feature at different atmospheric altitudes.

Over time, these observations could reveal how the wave moves, changes shape and interacts with Saturn’s surrounding atmospheric circulation.

Why This Discovery Matters

The Saturn decagon is important not simply because it looks unusual.

It provides scientists with a new natural laboratory for studying planetary atmospheres.

On Earth, atmospheric jet streams, waves and weather systems influence conditions across the planet. Saturn provides an entirely different environment in which researchers can study similar fluid-dynamics processes on a much larger planetary scale.

The southern decagon could therefore help scientists understand how large atmospheric waves form and evolve on gas giants.

It also demonstrates the scientific value of long-term observations.

A single photograph might have shown an unusual pattern, but years of Hubble and ground-based observations allow researchers to determine that the structure is changing over time.

Key Facts About Saturn’s 10-Sided Pattern

• Planet: Saturn
• Location: South polar region
• Shape: 10-sided atmospheric wave, or decagon
• Approximate latitude: 63° south
• Telescope: NASA Hubble Space Telescope
• Observations: Evidence extends back to 2023
• Discovery process: Ground-based observations followed by Hubble confirmation
• Program: Hubble Outer Planet Atmospheres Legacy (OPAL)
• Research publication: Science Advances
• Publication date: September 2, 2026
• Scientific significance: First large, regular-sided jet pattern observed in Saturn’s southern hemisphere.

Frequently Asked Questions

What is the 10-sided shape on Saturn?

It is a large atmospheric wave surrounding Saturn’s south pole. Scientists describe its regular 10-sided appearance as a decagon.

Did NASA discover a new structure on Saturn?

NASA’s Hubble Space Telescope provided observations confirming a previously unidentified 10-sided atmospheric wave at Saturn’s south pole. The feature was detected through a combination of ground-based and Hubble observations.

Is Saturn’s southern decagon like its northern hexagon?

They are similar in that both are large regular-sided atmospheric patterns associated with Saturn’s polar jet streams. However, the northern hexagon has been stable for decades, while the southern decagon appears to be evolving.

When was Saturn’s decagon first seen?

Researchers found evidence of the feature in Hubble observations dating back to 2023. Ground-based observers noticed subtle signs of the pattern in 2024, followed by additional observations in 2025.

Is Saturn’s 10-sided pattern permanent?

Scientists do not know yet. Continued observations will determine whether the decagon becomes a stable atmospheric feature or continues to evolve.

Is the decagon a solid object?

No. It is an atmospheric wave associated with a powerful jet stream in Saturn’s atmosphere. Hubble observations indicate that the structure extends through multiple atmospheric layers.

The Bigger Picture

Saturn has fascinated astronomers for centuries because of its rings, moons and extraordinary atmosphere.

Now, the discovery of a developing 10-sided wave at its south pole adds another mystery to the gas giant.

Scientists have spent decades studying Saturn’s famous northern hexagon. The newly identified southern decagon offers something different: the opportunity to watch a major atmospheric pattern develop and change over time.

For now, researchers are continuing to observe the planet to determine exactly what drives the formation and evolution of the unusual structure.

As Hubble continues monitoring Saturn, the decagon could provide new clues about the powerful atmospheric processes shaping the Solar System’s giant planets.

Sources & References

Primary source: NASA Science — NASA’s Hubble Tracks New Decagon Encircling Saturn’s South Pole.

Research paper: Agustín Sánchez-Lavega et al., A decagon wave around Saturn’s south pole, published in Science Advances, September 2, 2026.

NASA image/data: Decagon on Saturn’s South Pole (Color) and Decagon on Saturn’s South Pole (Single Filter).

NASA Saturn facts: Information on Saturn’s northern hexagon and atmospheric characteristics.

Editorial note: The Science Signal has distinguished confirmed observations from scientific questions that remain under investigation. The exact mechanism responsible for the southern decagon and its long-term stability have not yet been established.