Scientists discover massive 10-sided wave pattern in Saturn's south pole clouds

Saturn has revealed another geometric secret. In 2023, the Hubble Space Telescope caught sight of an enormous 10-sided wave pattern swirling through the icy ammonia clouds above the planet's south pole—a discovery that has forced planetary scientists to reconsider what they thought they knew about Saturn's atmosphere.

The formation, called a decagon, appears to dwarf Saturn's famous hexagon, the six-sided cloud structure that has circled the north pole since NASA's Voyager spacecraft first spotted it in the 1980s. A single edge of this new decagon already stretches beyond 10,000 miles, and the entire structure may still be growing. The Spanish-led research team, led by Agustin Sanchez-Lavega of the University of the Basque Country, suspects the decagon formed sometime between 2017 and 2023, during years when Saturn's south pole tilted away from Earth and vanished from view. The findings were published this week in Science Advances.

What makes the discovery significant is not just its size, but what it suggests about Saturn itself. For decades, the hexagon seemed like a singular oddity—a geometric anomaly that set Saturn apart from every other planet in the solar system. While all gas giants with atmospheres generate wave patterns and disturbances, Saturn alone produces them in the shape of polygons, those clean-edged geometric forms. The hexagon's persistence, visible for more than four decades, only deepened the sense that Saturn possessed something truly exceptional. The decagon changes that calculation. "The 'unique' hexagon is not as extraordinary as we thought," Sanchez-Lavega wrote in an email, suggesting that geometric formations may be a characteristic feature of Saturn's atmospheric machinery rather than rare accidents.

The two structures behave differently in ways that intrigue researchers. The hexagon sits nearly motionless on its jet stream, a stable anchor point in Saturn's roiling clouds. The decagon, by contrast, drifts eastward at a leisurely six miles per hour, a slow migration that distinguishes it fundamentally from its northern counterpart. Leigh Fletcher of the University of Leicester, who measured the winds within the decagon using the European Southern Observatory's Very Large Telescope in Chile, noted that "Saturn still has the ability to surprise us." The planet's capacity to generate these formations—and to do so in such orderly, polygonal shapes—remains poorly understood.

Scientists are now asking whether these geometric patterns might connect to similar phenomena elsewhere in the solar system. Sanchez-Lavega has begun wondering whether Saturn's decagon and hexagon might be related to the cyclones on Jupiter that also arrange themselves in polygonal configurations. If so, the two gas giants may operate according to shared atmospheric principles that have yet to be fully grasped. "This is a highly interesting phenomenon that appears to be unique to Saturn, and we want to know why," he said.

The immediate question is whether the decagon will endure. The hexagon has persisted for longer than a complete Saturnian year—thirty Earth years—a span of time that suggests remarkable stability. No one yet knows if the decagon possesses similar staying power or if it will dissipate within months or years. "For the time being, all I can confirm is that the decagon is still there," Sanchez-Lavega said. Over the coming years, as telescopes train their attention on Saturn's southern hemisphere with improving clarity, astronomers hope to capture finer details of the decagon's structure and behavior. Those observations may finally illuminate why Saturn, alone among the planets, sculpts its atmospheric disturbances into such precise geometric forms—and whether the solar system holds other such mysteries waiting to be seen.