Saturn Surprises Scientists... After 40 Years of Observation
Arabia.net – NASA’s Hubble Space Telescope, in collaboration with the European Space Agency, has captured a massive, evolving decagonal atmospheric wave encircling Saturn’s south pole, marking the first time such a regular, multi-sided jet pattern has been observed in the southern hemisphere of this gas giant.
The study documenting the discovery was published in the specialized scientific journal *Science Advances*. While the new shape bears a striking resemblance to the famous hexagon that has remained stable at Saturn’s north pole for decades, it differs in fundamental characteristics. This has led the research team to suggest that scientists may be witnessing a new weather phenomenon forming before their eyes on the planet’s surface.
Amy Simon, a co-investigator on the study and principal investigator of the OPAL (Outer Planet Atmospheres Legacy) program for monitoring exoplanet atmospheres at NASA’s Goddard Space Flight Center in Maryland, stated that she had never previously seen a similar phenomenon in Saturn’s southern hemisphere. She added that the northern hexagon has remained unchanged every time it has been observed over the past 40 years, whereas the new pattern appears different, gradually intensifying. This provides scientists with a rare opportunity to monitor the evolution of a giant weather pattern in real time.
The trail to the discovery began before Hubble’s involvement. Seasonal changes on Saturn gradually brought its south pole back into view from Earth, allowing amateur astronomers to detect initial features of the phenomenon through images collected from ground-based observatories worldwide. Agustín Sánchez-Lavega, a researcher at the University of the Basque Country in Spain and the study’s lead author, explained that these images were gathered via a university-run website called the Virtual Planetary Observatory Laboratory, which receives contributions from amateur observers around the globe.
Sánchez-Lavega further noted that he and amateurs Trevor Barry and Jean-Paul Aujoulat first noticed a subtle, wavy band at the south pole in 2024. Additional ground-based images taken in 2025 strengthened the strong possibility of a fully formed decagonal structure. At that point, the research team began utilizing Hubble observations, which, from its vantage point in space, provide unmatched image resolution across full rotational cycles of Saturn, free from distortion caused by Earth’s atmosphere. He pointed out that his team had been searching Hubble images since 1990 for a counterpart to the northern hexagon at the south pole, based on the known symmetry of Saturn’s jet streams in the northern and southern hemispheres. He noted that images from the Cassini spacecraft, which orbited the planet between 2004 and 2017, showed no indication of a long-term formation. However, Hubble data ultimately confirmed the existence of this phenomenon, tracing it back to 2023.
Furthermore, the study revealed that the decagonal wave is embedded within one of Saturn’s powerful jet streams and extends through multiple layers of the planet’s atmosphere. According to the researchers, this indicates that it is not merely a surface-level cloud phenomenon, but a vertically extensive atmospheric structure reaching deeper levels. The scientific team noted that the apparent position of the decagonal shape shifts slightly between images, as Hubble captures them at different wavelengths, each revealing a different altitude level within Saturn’s atmosphere.
Meanwhile, the scientific team noted that understanding how the decadal phenomenon forms, its potential duration, and whether it resembles or differs from the long-term Northern Hexad, would require further observations using the Hubble Space Telescope, alongside the James Webb Space Telescope—a joint project of NASA, the European Space Agency, and the Canadian Space Agency—as well as additional analyses based on specialized computer models.
