Hubble spots a mysterious 10-sided 'decagon' growing around Saturn's south pole

New Hubble observations have revealed a dramatic, 10-sided jet surrounding Saturn's south pole, and it appears to be evolving before our eyes.

The Hubble Space Telescope recently snapped a high-resolution view of the striking "atmospheric wave," which appears to have begun forming in 2023, archival Hubble images show. Scientists are curious about how this "decagon" popped up so quickly, given that Saturn's other famous multisided wave — a hexagon at the north pole — has been observed on the planet for 40-plus years.

"The question is, why did it suddenly form now when we haven't seen one before?" Amy Simon , a senior scientist at NASA 's Goddard Space Flight Center and co-author of a new study describing the observations, said in a statement .

"The northern hexagon has been there every time we've looked for more than 40 years," Simon added. "This feature is different — it appears to be strengthening, giving us the rare opportunity to watch a giant atmospheric pattern develop."

Scientists can see the wave persisting through several atmospheric layers, which means it extends beyond the cloud tops. The wave is also found in a large jet stream at Saturn. More observations with Hubble and the James Webb Space Telescope ( JWST ) will be required to see how the wave is generated and what the decagon illustrates about atmospheres in large gas giants like Saturn.

The images were obtained as part of Hubble's Outer Planet Atmospheres Legacy program, which uses some of the telescope's time to image the solar system 's outer planets — Jupiter, Saturn, Uranus and Neptune — once a year. The goal is to obtain long-term observations of these worlds, to supplement spacecraft orbiting or flying by.

From Earth's perspective, Saturn is slowly orbiting in its roughly 29-year journey of the sun so that its south pole is visible from our planet, allowing for a good view of the changing decagon. Hubble, in fact, was not the first to see signs of this decagonal shape; it was ground-based observatories that spotted a mysterious undulating band around Saturn’s south pole in 2024.

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