Scientists Identify Ten-Sided Jet Stream at Saturn’s South Pole Using Hubble Observations

Researchers monitoring weather patterns on Saturn have discovered a remarkable polygonal formation encircling the planet’s south pole—a feature that has intrigued scientists given its similarity to the well-known hexagonal jet at the northern pole.

The northern hemisphere has featured a distinctive hexagonal cloud band for at least 45 years, first observed by NASA’s Voyager probes during their flybys in 1980 and 1981. However, NASA’s Cassini mission, which conducted over 13 years of detailed observations of Saturn, never detected a comparable structure in the southern hemisphere, leaving scientists puzzled.

Using the Hubble Space Telescope alongside a network of amateur astronomers, researchers have now identified a 10-sided jet moving independently of the surrounding atmospheric currents around Saturn’s south pole, according to findings published September 2 in Science Advances. “This discovery suggests that the hexagon at the north pole is not as extraordinary as previously thought,” noted planetary scientist Agustín Sánchez-Lavega of the University of the Basque Country in Bilbao, Spain.

The decagon became visible in Hubble images captured last autumn, and astronomers subsequently reviewed observations from as early as 2023, confirming the feature was present though less distinct. The exact formation date remains uncertain, as no spacecraft has been stationed at Saturn since 2017, and the planet’s southern pole was not visible from Earth between 2012 and 2023.

Planetary scientist Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, indicated that the decagon appears more dynamic than its stable northern counterpart, making it difficult to predict how long the feature will persist on this turbulent gas giant. “Gas giants look nice and serene, but they’re very windy,” Simon explained. Atmospheric structures like the hexagon can endure for decades, yet circumstances can shift rapidly.

MIT planetary scientist Wanying Kang, who was not involved in the study, noted that jet streams on Saturn are not inherently unusual. The planet’s substantial size combined with its rapid rotation—completing a day in approximately 10.7 hours—creates ideal conditions for these striped gas currents to develop. Warm equatorial gases naturally flow toward the cooler poles, but the swift rotation deflects them into planetary paths before they can travel far. The decagon’s angular geometry rather than a smooth circular form suggests something noteworthy about Saturn’s deeper atmospheric layers.

While researchers cannot fully account for the phenomenon, they propose that disturbances from a neighboring storm may have initiated its formation. The team plans to employ additional observatories, including the James Webb Space Telescope, and conduct prolonged monitoring to determine the mechanism behind the decagon.

Hubble is already scheduled to revisit Saturn later this month. “We’ll be watching it, and we’ll go from there,” Simon stated.

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