APOD: 2026 September 8 – Hubble: Decagon Around Saturn’s South Pole

On September 8, 2026, the Astronomy Picture of the Day (APOD) showcased an intriguing geometric cloud pattern around Saturn's south pole, captured by the Hubble Space Telescope. Unlike Saturn's North Pole, which has been observed to feature a hexagonal (six-sided) cloud since its discovery in 1987 through NASA's Voyager spacecraft, the South Pole exhibits a distinct decagon (ten-sided) shape.

The geometric boundaries of Saturn's clouds may be the result of waves formed when fast-moving gas away from the poles interacts with slower-moving gas closer to the poles. This composite image, taken by Hubble last year, highlights the decagon pattern most prominently in the dark inner regions of Saturn's south pole. The X marking the South Pole is surrounded by bands of circulating clouds.

While the northern hexagon has remained stable for over forty years, the stability of the southern decagon remains a subject of ongoing research. The featured image showcases the Hubble's capabilities in revealing the complex and dynamic nature of Saturn's atmosphere, emphasizing the importance of continued observation and study of our celestial neighbors.