Astronomers using the Hubble Space Telescope have identified a giant 10-sided atmospheric wave around Saturn’s south pole, the first large regular-sided jet pattern observed in the planet’s southern hemisphere. The evolving structure, described in a study published September 2, 2026, offers researchers a rare chance to watch a planetary weather pattern take shape.
The feature is being called a decagon because its outline has 10 sides. It sits inside one of Saturn’s powerful jet streams and appears across observations made at different wavelengths, which probe different heights in the atmosphere. That evidence indicates the pattern is vertically extended rather than a simple shape traced by one layer of clouds.
How the Saturn decagon was found
The discovery did not come from a single dramatic photograph. Researchers assembled Hubble observations dating to 2023 and compared them with images contributed by ground-based observers. A subtle wave along the southern polar region was noticed in 2024 by planetary scientist Agustín Sánchez-Lavega and amateur astronomers Trevor Barry and Jean-Paul Oger. Ground-based images from 2025 strengthened the case.
Hubble then provided the resolution and repeated full-rotation coverage needed to confirm the geometry. The observations came from the telescope’s Outer Planet Atmospheres Legacy program, known as OPAL, which has photographed the outer planets every year for more than a decade.
That long baseline is crucial. Regular monitoring lets scientists separate a lasting atmospheric change from a passing visual effect and examine how storms and jet streams evolve with the seasons. NASA says the south-polar pattern can be traced back to 2023 and appears to be strengthening.
Why the finding is surprising
Saturn is already famous for a six-sided jet stream around its north pole. Spacecraft and telescopes have observed that northern hexagon for more than 40 years. Scientists had long searched for a southern counterpart because Saturn’s broad system of east-west jets is roughly symmetrical between hemispheres.
But Cassini, which orbited Saturn from 2004 to 2017, did not reveal a comparable long-lived polygon at the south pole. Hubble observations going back to 1990 also did not show the kind of stable southern structure researchers hoped to find. The new decagon is therefore not just a mirror image of the northern hexagon. Its recent emergence and different number of sides point to a distinct atmospheric development.
Saturn’s seasons helped make the discovery possible. As the planet moved along its orbit, the south pole gradually became better placed for observation from Earth. Ground-based contributors spotted the early hints, while Hubble’s position above Earth’s atmosphere provided sharper, unsmeared views.
A wave in the atmosphere, not a solid object
The geometric outline can look engineered in a still image, but it is a fluid pattern in Saturn’s moving atmosphere. Fast jet streams can support waves whose crests and troughs form repeating shapes around a pole. On Earth, atmospheric waves also influence the path of jet streams, though Saturn’s enormous scale, rapid rotation and hydrogen-rich atmosphere create very different conditions.
The apparent position of the decagon shifts slightly between Hubble filters because each wavelength samples a different altitude. Seeing the pattern in several layers gives scientists information about its vertical structure and may help them test models of how the wave is generated and maintained.
Researchers have not yet established what triggered the pattern, whether it will stabilize, or how long it will survive. Those are central questions, not minor uncertainties. Calling it a decagon describes the observed wave shape; it does not provide an explanation for the physics behind it.
What scientists will watch next
The team plans to keep observing Saturn with Hubble and study the planet with the James Webb Space Telescope, while using computer models to test possible mechanisms. Future observations can show whether the 10-sided form settles into a persistent configuration like the northern hexagon, changes its number or strength, or fades.
Repeated measurements at several wavelengths should also reveal how the pattern behaves at different atmospheric depths. If the decagon persists, scientists may be able to compare the speed, vertical reach and stability of the north and south polar jets. If it disappears, the record will still capture the life cycle of an unusual giant-planet weather system.
The discovery also demonstrates why sustained observing programs matter. A mission that revisits the same worlds year after year can detect gradual changes that one-off snapshots miss. Amateur observers contributed the first clues, professional analysis joined the record across years, and a space telescope supplied the decisive detail.
What the evidence does and does not show
The announcement is based on multi-year observations and a peer-reviewed study in Science Advances. NASA and ESA both describe the feature as an evolving atmospheric wave. Neither agency claims that scientists already understand its cause or that it will become permanent.
The most accurate takeaway is therefore measured: Saturn now shows a newly confirmed, 10-sided south-polar jet pattern that was not apparent in earlier long-term observations. The next chapter depends on time. Hubble, Webb, ground-based observers and atmospheric models will determine whether the decagon becomes a durable counterpart to the northern hexagon or a brief event unique to this Saturn season.
Sources: NASA’s September 2 Hubble report; ESA/Hubble science release; Science Advances study.
Read more recent space coverage in our report on NASA’s Mars telecommunications network contract.
Edin Pula
Edin Pula is the editor responsible for reviewing and publishing content at Smashology Media. He oversees sourcing, fact-checking, corrections, and editorial standards across coverage of internet culture, technology, entertainment, news, and crime.
