A crisp, ten-sided shape has been found circling Saturn's south pole, and it is not a trick of the light. The Hubble Space Telescope, operated by NASA in the United States, captured the feature in a new image released on September 8, 2026. The polygon, called a decagon, sits inside a swirling polar storm, and its sharp edges have left planetary scientists puzzled.
A geometric storm that should not be so tidy
The decagon appears as a dark, angular band wrapped around the planet's southern vortex. While Saturn is known for its hexagonal jet stream at the north pole, this southern decagon is far less regular. The image shows a bright disk near the center, with the ten-sided band cutting across the surrounding cloud layers. Hubble's resolution reveals that the shape is not perfectly symmetrical, but its straight segments are clear enough to count.
Why researchers are paying close attention
Saturn's north pole has a famous hexagon, a six-sided jet stream that has been studied for decades. The south pole, however, has shown mostly chaotic storm activity. Finding a decagon there suggests that the planet's atmospheric dynamics are more ordered than previously thought. The feature was spotted in ultraviolet and visible light, and it appears to be tied to the fast-moving polar jet. Local scientists at the Space Telescope Science Institute in Maryland are now comparing the southern decagon with the northern hexagon to understand how such stable polygons form in a gas giant's turbulent atmosphere.
The discovery matters because it offers a new natural laboratory for studying fluid motion on a massive scale. On Earth, similar shapes do not appear in weather systems, but on Saturn, the combination of rapid rotation and internal heat can create these striking patterns. The fact that the decagon is not as clean as the hexagon suggests that the southern jet is weaker or more disturbed, yet it still holds its ten-sided outline.
For the people who study Saturn, this is a reminder that the planet still holds surprises. Hubble has been observing the ringed world for years, but this is the first time a decagon has been clearly documented at the south pole. The image was released as part of NASA's Astronomy Picture of the Day series, drawing attention from amateur skywatchers and professional researchers alike.
The decagon is not a solid structure, but a fast-moving ribbon of wind. Its persistence over time, even with slight wobbles, points to a deep atmospheric process that keeps the shape stable. As Hubble continues to monitor Saturn, scientists hope to track how the decagon changes with the seasons. For now, the ten-sided storm stands as a fresh example of how much remains unknown about the outer planets, even those we have visited with spacecraft.
