Astronomers using NASA’s Hubble Space Telescope have discovered an enormous 10-sided wave pattern swirling in the icy ammonia clouds over Saturn’s south pole, according to a Spanish-led research team publishing in the journal Science Advances. The spinning, meandering decagon spans distances where a single side exceeds 10,000 miles, marking the first time scientists have observed a large, regularly shaped jet pattern in the planet’s southern hemisphere.
Saturn’s New Decagon Versus the Northern Hexagon
The newly spotted atmospheric feature sits on a powerful jet stream and migrates eastward at a tame 6 mph (10 kph), according to study lead author Agustín Sánchez-Lavega with the University of the Basque Country. That slow movement contrasts with Saturn’s famous northern hexagon, which is practically stationary. While all solar system planets with atmospheres feature wave-spawning disturbances, only Saturn churns them out looking like polygons bounded by straight lines, according to Sánchez-Lavega.
Observations show the decagon extends through several layers of the atmosphere rather than existing solely at the cloud tops, according to findings discussed by Amy Simon, study co-author and Outer Planet Atmospheres Legacy (OPAL) principal investigator at NASA’s Goddard Space Flight Center. Researchers like the University of Leicester’s Leigh Fletcher measured winds within the structure using the European Southern Observatory’s Very Large Telescope in Chile, adding ground-based data to the space-based imaging.
How Amateur Astronomers and Hubble Spotted the Wave
The discovery relied on a mix of ground-based observations and space telescope imaging. Sánchez-Lavega, alongside amateur astronomers Trevor Barry and Jean-Paul Oger, noticed a faint, wavy band near Saturn’s south pole in images from 2024 submitted to the Planetary Virtual Observatory Laboratory. Stronger ground-based evidence collected in 2025 prompted researchers to pull older data from Hubble’s OPAL program.
The Hubble data confirmed the feature’s presence back to 2023, according to NASA. Researchers suspect the bizarre atmospheric phenomenon formed between 2017 and 2023 when Saturn’s south pole was tilted away from Earth and hidden from view. Decades of prior spacecraft observations by NASA’s Voyager missions in the 1980s and the Cassini orbiter between 2004 and 2017 showed no inkling of a long-lived formation at the south pole, leaving scientists questioning why the decagon formed recently.
Comparing Gas Giant Weather Patterns
By comparing the northern hexagon and the southern decagon, researchers hope to decode the weather patterns of giant gas planets. Sánchez-Lavega noted that scientists want to explore whether these polygon jet streams relate to the polygonal arrangements of cyclones seen on Jupiter. It remains unclear whether Saturn’s decagon will last as long as the northern hexagon, which has been visible by spacecraft for more than 40 years—longer than a 30-Earth-year Saturnian year.
“For the time being, all I can confirm is that the decagon is still there,” Sánchez-Lavega said. Improving views of Saturn’s southern hemisphere over the coming years should allow astronomers to capture sharper details and determine whether the structure will stabilize or dissipate.
Frequently Asked Questions
What is Saturn’s new southern feature?
Astronomers discovered a massive 10-sided wave pattern, or decagon, swirling in the icy ammonia clouds over Saturn’s south pole, according to research published in Science Advances.
How does the decagon compare to the northern hexagon?
While Saturn’s northern hexagon is practically stationary, the newly discovered decagon migrates eastward at about 6 mph (10 kph). Both sit on jet streams, but researchers note the southern decagon appears larger and potentially less stable.
When did the decagon form?
Researchers suspect the decagon formed between 2017 and 2023, while Saturn’s south pole was tilted away from Earth and out of sight. Hubble images confirmed its presence starting in 2023.
Who discovered the Saturn decagon?
A Spanish-led research team, including lead author Agustín Sánchez-Lavega of the University of the Basque Country, identified the feature using Hubble Space Telescope data alongside ground-based observations contributed by amateur astronomers.
Want to stay updated on future planetary discoveries and space exploration milestones? Subscribe to our space science newsletter or drop a comment below to share your thoughts on Saturn’s bizarre weather patterns.