At Saturn’s stormy south pole, an unusual 10-sided weather pattern has come to light. This kind of geometric structure, which researchers are calling a decagon wave, hasn’t been observed at Saturn’s south pole before, and it could be the key to deciphering certain properties of the gas giant's atmosphere.
First spotted by Hubble in 2023, the decagon wave at Saturn’s south pole has now been described in a new Science Advances study; it’s not the first geometric pattern to appear on Saturn, however. Another wave at the planet’s north pole, shaped like a hexagon rather than a decagon, has been known since the 1980s. Researchers are interested in finding out how these waves on opposite poles are similar — and just as importantly, how they are different.
“Given Saturn’s symmetry in its north-south jet stream system, we have been searching for a counterpart to Saturn’s northern hexagon on the south pole in Hubble images since 1990,” said study lead author Agustín Sánchez-Lavega, a researcher at the University of the Basque Country, in a statement from NASA.
Spotting a Decagon at Saturn's South Pole
The top image shows Saturn as captured by the Hubble Space Telescope at a wavelength of 763 nm on 29 August 2025. The yellow box indicates the region shown on the polar map (bottom image), where the black arrow marks the position of the decagon.
(Image Credit: NASA, ESA, A. Sánchez-Lavega (Basque Country University, EHU))
In October 2023, researchers saw the first signs of Saturn's decagon wave while looking through red-filtered images taken by the Hubble Space Telescope (HST). Further observations in 2024 and 2025 gave them a clear picture of the pattern gathering at the planet’s south pole.
Explore All OptionsLong before the decagon wave was discovered at the south pole, the hexagon wave at the north pole had grabbed astronomers' attention. This 6-sided wave, revealed in images taken during flybys of NASA’s Voyager mission in 1980 and 1981, is known to be remarkably stable. It has persisted for over 40 years at this point, without experiencing substantial changes.
The decagon wave at the south pole, by contrast, seems to be actively evolving.
"We've never seen anything quite like this in Saturn's southern hemisphere," said study co-author Amy Simon, principal investigator of Hubble's Outer Planet Atmospheres Legacy (OPAL) program. "The northern hexagon has been there every time we've looked for more than 40 years. This feature is different — it appears to be strengthening, giving us the rare opportunity to watch a giant atmospheric pattern develop."
Enclosed in a Jet Stream
The decagon wave sits in one of Saturn’s jet streams, but it also extends through multiple layers of the planet’s atmosphere, according to NASA.
To get a better idea of how atmospheric conditions led to the wave’s development, researchers used shallow water model simulations. These tests represented a simplified version of Saturn’s troposphere, the lowest atmospheric layer where weather patterns are shaped.
The researchers concluded that the wave may have been created by a spatially periodic disturbance in a zonal jet stream or driven by a swirling vortex that might be near a Red Spot (a storm system) slightly to the north.
The researchers still don’t know exactly how the decagon wave formed, but further studies may provide more insight on the atmospheric factors that drive its development. They plan on keeping an eye on the wave to see whether it will continue to evolve or settle into a steady state like the north pole hexagon.
Differences in Weather
At Saturn’s poles, symmetrical jet streams have formed, but the same level of symmetry is nowhere to be seen in Earth’s atmosphere — why is that?
According to NASA, there are a few reasons why Earth's atmosphere doesn't have near-perfect hexagon- or decagon-shaped structures like Saturn. One is that since Earth is closer to the sun than Saturn is, it receives nearly 100 times more sunlight than Saturn, driving wind and weather patterns that are more free-flowing. The Earth’s surface is also non-uniform, with towering mountains disturbing atmospheric flow.
These conditions make it so that jet streams can’t settle into symmetric shapes in Earth’s atmosphere. Saturn’s atmosphere, on the other hand, easily holds symmetric jet streams like its hexagon and decagon waves because it has no solid surface and its composition is far more uniform than Earth’s.
So while Earth’s atmosphere is rather chaotic in that it's always whipping up new, short-lived storms, Saturn’s atmosphere displays waves that can remain steady for decades or centuries.
Read More: A Rogue Planet the Size of Saturn Detected 10,000 Light-Years From Earth
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Science Advances: A decagon wave around Saturn’s south pole
- This article references information from NASA: Cassini: Saturn's Perplexing Hexagon
