A southern counterpart — but not a copy
Saturn's north-polar hexagon has been observed for decades. The new southern structure has ten sides, appears to be strengthening and had no clear long-lived counterpart in Cassini observations. Researchers therefore describe it as a distinct and evolving phenomenon, not simply the familiar hexagon repeated in the south.
Years of observations revealed the pattern
Ground-based observers noticed a subtle undulating band in 2024 imagery and a stronger signal in 2025. Hubble's annual Outer Planet Atmospheres Legacy programme then confirmed that traces were already present in observations from 2023.
Different wavelengths probe different heights
The apparent position of the decagon shifts slightly between Hubble wavelengths. Because those filters sample different altitudes, the team concludes that the wave extends vertically through the atmosphere rather than existing only in one visible cloud layer.
The next test is whether it lasts
Continued observations by Hubble and the James Webb Space Telescope, combined with atmospheric models, are needed to determine what drives the wave and whether it settles into a stable configuration or fades as Saturn's seasons change.
Sources & Methods
LUMACTA NEWS compared the ESA/Hubble science release, its exact image record, ESA's parallel release and NASA's mission account. We distinguished observations from hypotheses and did not infer the feature's cause from the image.
- ESA/Hubble — Hubble tracks new decagon — primary science release
- ESA/Hubble — Decagon colour image — exact image and credit record
- ESA — Hubble tracks new decagon — agency release and licence record
- NASA — Hubble tracks Saturn's south-pole decagon — mission release