Hubble Space Telescope Detects New Decagonal Pattern on Saturn's South Pole

The National Aeronautics and Space Administration (NASA) Hubble Space Telescope has identified a large, ten-sided atmospheric pattern circling Saturn's south pole. This marks the first time scientists have observed a regularly shaped jet pattern of this size in Saturn's southern hemisphere. The structure shares similarities with Saturn's well-known hexagon at its northern pole, but key differences suggest it is a distinct atmospheric phenomenon.

Researchers reconstructed the feature's development using several years of Hubble observations, dating back to 2023. Earlier images showed faint indications before it evolved into the clearer pattern seen recently. These observations came from Hubble's Outer Planet Atmospheres Legacy (OPAL) program, which captures annual images of the outer planets. The findings were published in the journal *Science Advances*.

Saturn's changing seasons played a role in the discovery. As the planet progressed through its seasonal cycle, its south pole became visible from Earth. Astronomers using ground-based observatories first noticed the unusual structure. In 2024, a faint, wavy band appeared near the south pole. By 2025, ground-based observations provided stronger evidence that the feature had developed into a decagon.

Scientists then used Hubble for a more detailed view. The space telescope provides sharper images across full rotations of Saturn, avoiding atmospheric blurring. The newly identified wave lies within one of Saturn's powerful jet streams. Observations indicate it extends through multiple atmospheric layers, suggesting it is a vertically extended structure. Its apparent location shifts slightly depending on the wavelength used, which allows astronomers to observe different altitudes.

Researchers do not yet know what triggered the decagon or if it will remain stable. Additional observations from Hubble and NASA's James Webb Space Telescope, along with computer modeling, will be necessary. These efforts will help determine its formation, potential longevity, and its relationship to Saturn's northern hexagon. Long-term observations from programs like OPAL are crucial for monitoring such atmospheric changes over time.