Observations by the Hubble Space Telescope have revealed a massive, ten-sided atmospheric wave circling Saturn's south pole. This is the first time such a regular pattern has been discovered in the planet's southern hemisphere, reminiscent of the famous hexagon at the north pole – but also different in a way that may point to a new, evolving atmospheric phenomenon. The study is published in Science Advances
Hubble Space Telescope Discovered around the South Pole of Saturn Unusual phenomenon: a huge atmospheric wave in the form of Decagon – Ten-sided polygonThis is the first time that a large, regular pattern of this type has been discovered in Saturn's southern hemisphere, and researchers believe that we may be witnessing the development of a new atmospheric phenomenon on the gas giant.
The discovery is described inA study published in the journal Science Advances, led by Agustin Sánchez-Lavega from the University of the Basque Country in Spain.
A young cousin to the famous hexagon
The decagon immediately reminds us of theמשושה The famous one circling Saturn's north pole. The hexagon is a jet stream system that forms an almost geometric pattern around the pole, and it was already observed in Voyager images in the early 1980s and continued to appear in later observations.
But the southern decagon is not simply a version with four more sides of the northern hexagon.
According to the researchers, the northern hexagon appears to have been stable for more than four decades, while the new structure at the south pole appears to be Strengthening and organizing itself in recent years.
Amy Simon of NASA's Goddard Space Flight Center, co-author of the study and principal investigator of the program OPAL, says that the possibility of observing such a structure as it evolves gives scientists a rare opportunity to understand how huge planetary waves form in the atmospheres of gas giants.
First hints in 2023
The decagon was not discovered in a single image.
The researchers went back to Hubble observations from 2023 and found early hints of structure. In the years that followed, the pattern became clearer.
The observations were made as part of a program OPAL – Outer Planet Atmospheres Legacy, through which Hubble annually photographs Jupiter, Saturn, Uranus, and Neptune. The continuous monitoring allows scientists not only to take "pretty pictures" of the planets, but to detect atmospheric changes that last for years.
according to NASA announcement of the discoveryGround-based photographs from 2024 first drew the attention of Sánchez-Lavega and amateur astronomers Trevor Barry and Jean-Paul Auger to a wavy band in the South Pole region.
Additional observations from the ground in 2025 strengthened the suspicion.
Then grief comes into the picture.
Hubble sees from the ground, it's hard to see
Ground-based telescopes must view Saturn through Earth's atmosphere, which distorts and blurs the image to some extent.
Hubble, located above the atmosphere, is able to image Saturn in high resolution over an entire rotation of the planet and examine it at several wavelengths.
The Hubble images revealed that the southern strip does indeed form a ten-sided structure.
Even more important: the decagon is not just a drawing in the upper clouds.
It lies within one of Saturn's powerful jet streams and extends through several layers of the atmosphere. The fact that its apparent position changes slightly between images taken at different wavelengths suggests that the structure exists at different altitudes.
In other words, it is a three-dimensional atmospheric system and not just a row of clouds that happened to be arranged in a polygonal shape.
Cassini didn't see it.
One of the most surprising details is that the structure was probably not there – at least not in its current form – when The Cassini spacecraft explored Saturn.
Cassini Orbited Saturn between 2004 and 2017 and returned to Earth vast amounts of information and detailed photographs of the atmosphere, rings, and moons.
However, the researchers note that Cassini images show no sign of a long-lived southern structure similar to the current Decagon.
Sanchez-Lavega says that researchers have actually been looking for a southern equivalent of the northern hexagon since 1990.
The fact that the decagon only appears in recent observations strengthens the possibility that we are seeing A structure that was born right in the current decade.
Why now?
This is still an open question.
The seasonal changes on Saturn may play a role. Saturn orbits the Sun once every 29.5 Earth years, so each season lasts more than seven years.
For many years, Saturn's south pole was more difficult to observe from Earth. Seasonal changes in the angle of illumination and viewing angle gradually brought it back into astronomers' field of view.
But the fact that the pole can now be seen does not in itself explain why the structure was created.
"The most intriguing part for me is that it seems to have just recently formed," Simon said in a NASA statement. The main question now is why the phenomenon appeared now, after decades of not being seen.
How does an atmosphere create a polygon?
The appearance of hexagons, decagons, and other geometric patterns in an atmospheric system sounds almost artificial, but it could stem from the laws of physics of flows.
Fast jet streams can develop large waves that spread around the planet. Under certain conditions, the wave can stabilize into a number of peaks and troughs, and when viewed from above it appears as a polygon.
Saturn's Northern Hexagon is one of the most famous examples of this phenomenon.
The Southern Decagon now gives scientists another natural laboratory – and one that is especially important if it can actually be observed as it forms.
Hubble and Webb will continue to follow
The researchers plan to continue observing Saturn with Hubble and examine whether the decagon stabilizes into a permanent structure or continues to change.
is also James Webb Space Telescope It may help because it can examine the atmosphere at infrared wavelengths and study different layers than those seen in Hubble images.
The big question is whether in a few decades astronomers will talk about the "southern decagon of Saturn" as naturally as they do today about the northern hexagon – or whether the pattern will disappear again.
Even after Decades of research by ShabtaiIt turns out that the gas giant is still capable of producing surprises on a planetary scale.
Questions and Answers
What was discovered at Saturn's south pole?
Hubble Space Telescope He discovered a large atmospheric wave in the shape of a decagon – a ten-sided polygon – encompassing the south polar region of Saturn.
Is it similar to Saturn's hexagon?
Yes, but not completely. Both structures are associated with large jet streams in the atmosphere, but the northern hexagon is stable and has been observed for more than 40 years, while the southern decagon appears young and changing.
When was the Decagon created?
It is not known exactly. Hubble observations allow us to detect hints of its existence as early as 2023, and it has become clearer in the years since. No similar long-lived structure has been found in the old Cassini images.
Are these just polygon-shaped clouds?
No. The observations at different wavelengths indicate that the wave extends through several layers of the atmosphere and is located within a strong jet stream.
More on the subject on the science website
- The farewell mission of Cassini - NASA's most beloved spacecraft
- The kings of the solar system - Saturn
- It's cold in Saturn's rings
- The winds on Saturn have weakened
- Cassini sent a picture of Saturn from about 300 million kilometers away
For the scientific article: Opening the scientific article
