Saturn south pole atmospheric decagon discovery

Astronomers have identified a massive, ten-sided atmospheric wave, referred to as a ‘decagon’, encircling Saturn’s south pole. This phenomenon was detected using data from NASA’s Hubble Space Telescope alongside observations from ground-based and amateur telescopes. The decagon is a three-dimensional weather system embedded within a high-speed jet stream. While the jet stream moves at high velocities, the decagon itself migrates eastward at approximately 10 kilometers per hour. Researchers noted that the structure extends through multiple layers of the planet's atmosphere. The discovery follows observations of the structure evolving over several years; faint hints were noted in 2023, clarity increased in 2024, and a distinct ten-sided shape became visible in 2025 as Saturn’s seasonal tilt brought the south pole back into view. The decagon, which has a diameter of roughly 167,820 kilometers, serves as a southern counterpart to the well-known six-sided hexagon at Saturn’s north pole. In a study published in Science Advances, researchers noted that the decagon is significantly larger than the northern hexagon. Each of its ten sides spans approximately 16,780 kilometers. Unlike the stable northern hexagon, the southern decagon appears to be a relatively recent development. While earlier estimates suggested emergence between 2023 and 2025, recent analysis indicates the pattern may have formed between 2017 and 2023, during a period when the planet’s tilt kept the southern hemisphere hidden from Earth. Agustin Sanchez-Lavega from the University of the Basque Country and other researchers suggest the structure is driven by powerful jet streams. The decagon is described as more unstable than the northern hexagon. Lead researcher Agustin Sanchez-Lavega stated that this finding helps deepen the understanding of planetary meteorology by proving the northern hexagon is not a singular occurrence.