Astronomers using the Hubble Space Telescope have discovered a growing decagon-shaped wave around Saturn’s south pole, revealing a 10-sided storm that developed between 2023 and 2025. According to a paper published in Science Advances, this newly spotted southern feature contrasts sharply with the famous six-sided hexagonal storm that has persisted on Saturn’s north pole for decades.
Hubble Spots a 10-Sided Storm on Saturn’s South Pole
When NASA’s Voyager spacecraft flew past the gas giant in 1980, it recorded a colossal, six-sided storm swirling around the northern polar region. That northern hexagon spans roughly twice the width of Earth and measures between 20,000 and 25,000 miles across, with jet streams extending 180 to 200 miles above the cloud tops, according to mission data. Scientists first identified the feature in 1988 while reviewing Voyager data, and the later Cassini spacecraft mission confirmed its long-term stability.
For decades, researchers searched for a matching wave in Saturn’s southern hemisphere, expecting a similar subpolar jet feature. However, Saturn’s tilted axis kept the south pole hidden from Earth-based telescopes beginning in 2012.
Comparing Saturn’s Northern Hexagon and Southern Decagon
While the northern hexagon has remained remarkably stable for more than 40 years, the southern decagon exhibits dynamic and shifting behavior. According to the study published in Science Advances, the longitudes of the decagon’s vertices shift back and forth over a roughly 32-day cycle. Of the 10 sides observed by Hubble, three are very prominent, four are less prominent, and three remain less defined.
Researchers used shallow-water model simulations to test how the decagon formed. The modeling suggests the 10-sided shape may emerge from a repeating disturbance along the jet’s peak or could be driven by a large, counterclockwise-rotating vortex located to its north. These findings indicate that the southern decagon operates as a meandering atmospheric wave held in place by a powerful jet, rather than a rigid structure.
Did you know? Saturn’s northern hexagon is so massive that two Earths could easily fit side-by-side inside the stormy boundary.
Frequently Asked Questions
When was Saturn’s southern decagon discovered?
Astronomers first spotted the 10-sided structure in October 2023 using images captured by the Hubble Space Telescope, with the shape becoming fully developed by 2025.
How does the southern decagon differ from the northern hexagon?
While the northern hexagon has remained stable for over four decades, the southern decagon shifts back and forth over a 32-day cycle and appears to be a transient, evolving atmospheric wave.
Why was the southern storm undiscovered for so long?
Saturn’s axial tilt hid its southern hemisphere from Earth-based observation starting in 2012, preventing telescopes from viewing the south pole until the planet’s orbit brought the region back into view in late 2023.
What are your thoughts on Saturn’s shifting weather patterns? Leave a comment below or explore more space exploration articles on our site.
Related reading