Saturn's south pole is concealing a strange secret: a massive, ten-sided cloud structure encircling the polar vortex. This geometric surprise was recently confirmed by researchers using the Hubble Space Telescope, a shape that might challenge long-held theories about planetary atmospheres.
A decagon at the pole.
Images captured by Hubble show what appears to be a near-perfect decagon—a ten-sided polygon—around Saturn's southern polar region. The sides form a jagged but nearly straight-edged ring roughly 60 degrees from the planet's south pole. This region is known for its powerful jet stream and hurricane-like vortex, but the distinct angular shape is something scientists weren't looking for.
This comes after decades of observing Saturn's north pole, which hosts a famous hexagonal storm system. The north pole's hexagon has been a curiosity since the Voyager missions in the 1980s, with its six sides likely created by a jet stream of winds. Now, the south pole offers a ten-sided counterpart, suggesting that such angular structures might be a common, yet unpredictable, trait of gas giants.
The discovery was made from a series of Hubble observations. Photos processed to highlight cloud features revealed the decagon's edges, appearing like ridges built by atmospheric flows.
Researchers are not entirely sure why these shapes form. The hexagon on the north has been linked to balanced wind speeds and rotation, but reproducing the same effect for a decagon—which would require different wind dynamics—poses new questions. The new structure appeared recently in time-lapse imagery, hinting that the south polar atmosphere may be more variable and complex than previously thought.
Members of the scientific community are intrigued that a second, even higher-sided polygon exists. Some suggest the answer might lie in differences in how the two poles interact with the planet's overall rotational and magnetic forces. However, no model has fully explained Hubble's new imagery yet.