Saturn Has a 10-Sided Mystery: Astronomers Discover Massive ‘Decagon’ Around South Pole

Astronomers analysing high-resolution observations from NASA's Hubble Space Telescope have discovered a massive, 10-sided atmospheric wave pattern encircling Saturn's south pole. The newly confirmed structure, termed a "decagon," spans roughly 104,250 miles (167,820 kilometers) across, making it vastly larger than the planet's famed northern hexagon. The discovery, detailed in a study published in Science Advances, marks the first time a regular, large-scale polygonal jet pattern has been observed in Saturn's southern hemisphere, offering planetary scientists an unprecedented look at a giant atmospheric vortex actively forming in real time.

Ground-To-Space Collaborative Discovery

Because of the geometry of Saturn's axial tilt and its 29.5-year orbit, the planet's southern hemisphere was tilted away from Earth's direct line of sight between 2012 and 2023. As seasonal shifts brought the south pole back into view, ground-based astronomers were the first to catch glimpses of an anomaly. Dark Matter: Scientists Detect Single Mysterious Signal in LUX-ZEPLIN Experiment.

Lead author Agustin Sanchez-Lavega, a planetary scientist at the University of the Basque Country in Spain, identified a faint, undulating band in southern polar images submitted to the university's Planetary Virtual Observatory Laboratory in 2024. Amateur astronomers Trevor Barry and Jean-Paul Oger contributed key observations, which grew clearer in ground images captured throughout 2025.

To verify the phenomenon free from atmospheric distortion, researchers turned to Hubble's Outer Planet Atmospheres Legacy (OPAL) program. The space telescope's long-term observations confirmed subtle hints of the feature beginning as early as 2023, before it resolved into a sharply defined 10-sided perimeter. Scientists Turn Plastic Waste Into Edible Cookies Using Genetically Engineered Yeast.

Multi-Layered Dynamics And Scale

The decagon sits embedded within one of Saturn's high-speed southern jet streams located around 60 degrees south latitude. Each of its 10 geometric sides spans approximately 10,425 miles (16,782 km). The wave rotates at a gradual pace, taking around 800 Earth days to complete a single rotation around the planet.

Hubble's multi-wavelength observations revealed that the decagon is not merely a superficial cloud-top boundary, with imaging across different filters penetrating varying altitudes confirming the wave extends through multiple vertical layers of Saturn's atmosphere. Computer simulations led by the research team indicate the geometric shape arises from a meandering atmospheric wave trapped inside the high-speed jet stream, similar to hydrodynamic behaviours observed in shallow-water fluid models.

Contradicting Decades Of Symmetry Searches

For decades, Saturn's north pole stood out as a meteorological anomaly. Its famous hexagon, roughly 20,000 miles (32,000 km) wide, was discovered in 1988 using archival data from the Voyager 1 and 2 flybys and has persisted unchanged through every major observation since.

Planetary scientists spent decades hunting for a southern counterpart, expecting symmetrical behaviour across the planet's hemispheres. Yet observations spanning from Hubble's initial 1990 runs through NASA's Cassini mission, which orbited Saturn between 2004 and 2017, detected no persistent geometric boundaries in the south. Unlike the northern hexagon, which maintains uniform contrast across all vertices, the southern decagon shows varying darkness along its edges, pointing to an evolving, dynamic system rather than a long-stabilised structure.

What's Next

The emergence of the decagon provides a rare opportunity to observe how large-scale gas-giant weather patterns form and whether they achieve long-term equilibrium. Astronomers plan to track the south pole using both Hubble and the James Webb Space Telescope over the coming years, with a primary objective being to determine whether the structure will remain stable or destabilise as solar radiation peaks over Saturn's southern latitudes around 2032.

(The above story first appeared on LatestLY on Sep 04, 2026 03:37 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).