Scientists discovered a decagon-shaped wave in Saturn's southern atmosphere, a 10-sided phenomenon that appears to have formed recently over the planet's south pole. ^[1] Scientists discovered an enormous 10-sided wave pattern in the icy ammonia clouds over Saturn's south pole. ^[2] NASA's Hubble Space Telescope data revealed a massive decagon-shaped cloud wave at Saturn's south pole. ^[3] Agustín Sánchez-Lavega, lead author of the study, said there is no single model to explain the wave, and it may result from an instability in the jet stream or a wave forced from deeper levels of Saturn's atmosphere. ^[4] Older imaging from the Hubble Space Telescope and NASA's Cassini probe showed no such structure, and Hubble photographs from 2023 first showed the wave taking shape, becoming fully developed in images taken in August and September 2025. ^[5] The wave is described in a study published on 2026-09-02 in the journal Science Advances, led by Agustín Sánchez-Lavega, a physicist at Spain's Bilbao School of Engineering. ^[6] A single side of the decagon already exceeds 10,000 miles (16,700 kilometers). ^[7] Researchers suspect the bizarre atmospheric phenomenon may have formed between 2017 and 2023, when Saturn's south pole was tilted away from Earth and therefore out of view. ^[8] The spinning, meandering decagon appears to be even bigger and more unstable than the hexagon of clouds around Saturn's north pole that was spied by NASA's twin Voyagers in the 1980s. ^[9] The decagon-shaped cloud wave represents the first regular jet stream pattern ever observed in Saturn's southern hemisphere. ^[10] The structure began forming in 2023 and was initially detected by researchers at the University of the Basque Country in Spain and amateur astronomers using ground-based telescopes. ^[11] Researchers plan to continue observations using both the Hubble and James Webb Space Telescopes to determine if the structure will become a permanent feature like the north pole's hexagon. ^[12]