How did Saturn grow a 10-sided polar wave?
Hubble observations dating to 2023 show a giant, evolving 10-sided wave near Saturn’s south pole, the first large regular-sided jet pattern observed in the planet’s southern hemisphere.[1][6] Ground-based observers detected an undulating band in 2024, while polar projections of Hubble images from 2024 and 2025 clearly revealed the decagon near 63°S.[1][6]
Why it matters
Unlike Saturn’s northern hexagon, which has persisted through more than 40 years of observations, the southern decagon appears to have formed recently and is still strengthening, giving researchers a rare opportunity to watch a planet-scale atmospheric pattern develop.[6]
Key insights
- Different Hubble filters show that the decagon extends through multiple atmospheric layers rather than existing only at cloud level.[1][6]
- Its visible upper-tropospheric winds move at roughly 400 kilometers per hour.[1]
- A nearby anticyclone first observed in 2023 darkened sharply in 2025 before the decagon emerged, making it a possible source of the initial disturbance.[1]
- Researchers still do not know which aerosols produce the wave’s blue color or how its structure continues deeper into Saturn’s atmosphere.[1]