Recent observations using NASA's Hubble Space Telescope have uncovered a massive, evolving atmospheric wave with 10 sides encircling Saturn's south pole. This is the first time such a large, regularly shaped jet pattern has been observed in the planet's southern hemisphere. The structure resembles Saturn's well-known hexagon at the north pole but is distinct, hinting at a new atmospheric phenomenon on the gas giant. The findings were published in the journal Science Advances and offer a fresh perspective on Saturn's complex weather systems. The discovery was made by analyzing Hubble data collected over several years, starting in 2023, as part of the Outer Planet Atmospheres Legacy (OPAL) program. This program has captured annual images of the outer planets for over a decade. Saturn's seasonal changes gradually brought its south pole into view from Earth, allowing astronomers to detect the feature. Agustín Sánchez-Lavega, lead author of the study and a researcher at the University of the Basque Country in Spain, noted that the initial hints of the structure were seen in images from 2024, contributed by amateur astronomers and collected through the university’s Planetary Virtual Observatory Laboratory. Further ground-based observations in 2025 confirmed the presence of a decagon-shaped structure, prompting the use of Hubble to capture more detailed images. Hubble’s ability to observe from space provides sharper images and higher resolution than ground-based telescopes, avoiding the distortion caused by Earth's atmosphere. The wave is embedded within one of Saturn’s powerful jet streams and spans multiple atmospheric layers, indicating it is not just a surface-level cloud formation but a complex, vertically extended structure. The decagon is approximately 104,250 miles (167,820 kilometers) wide, with each side measuring about 10,425 miles (16,782 kilometers). It rotates slowly, completing one full cycle around Saturn every 800 days. The structure appears to vary in darkness, suggesting it may still be evolving. Scientists plan to use Hubble, NASA’s James Webb Space Telescope, and computer models to study the decagon’s formation, duration, and how it compares to the hexagon in the north, which has remained stable for over 30 Earth years. This discovery challenges the previous belief that the hexagon was a unique feature and highlights the dynamic and diverse nature of Saturn’s atmosphere.