For more than 150 years, astronomers have watched Jupiter’s Great Red Spot swirl across the planet’s atmosphere. But new observations from the Hubble Space Telescope have revealed something no one expected — this enormous storm behaves more like a bowl of wobbling jelly than a stable weather system.
Imagine a stress ball being squeezed and released, or a beating heart pulsing in slow motion. That’s how scientists describe the strange motion now seen in Jupiter’s Great Red Spot. According to findings published in the Planetary Science Journal, the storm is far less stable than it appeared during a century and a half of continuous observation.
A mystery with no clear explanation
Between December 2023 and March 2024, Hubble closely monitored the storm, capturing a series of high-resolution images. The results were startling: the Great Red Spot seems to expand and compress in a rhythmic cycle while speeding up and slowing down. Its central region even grows brighter as it swells.
“This is completely unexpected. For now, we have no explanation,” said Amy Simon of NASA’s Goddard Space Flight Center.
NASA’s official Hubble account shared the discovery on X (formerly Twitter), posting:
“Jupiter’s Great Red Spot is full of surprises. Hubble’s new observations of this famous storm discovered that its size isn’t as stable as once thought. It’s squeezing in and out at the same time as it moves faster and slower.”
Jupiter’s Great Red Spot is full of surprises.
Hubble’s new observations of this famous storm discovered that its size isn’t as stable as once thought. It’s squeezing in and out at the same time as it moves faster and slower.
Find out more: https://t.co/WjrG28fl57 pic.twitter.com/WgzViBr9YC
— Hubble (@NASAHubble) October 9, 2024
Scientists still don’t have enough data to fully understand what’s happening. The latest Hubble campaign only covered a single oscillation cycle, leaving plenty of questions unanswered. Future high-resolution imaging should help identify what drives the storm’s changing shape, size, and color.
Why the Great Red Spot matters
Over longer periods, astronomers have confirmed that Jupiter’s Great Red Spot is gradually shrinking. Eventually, it may settle into a smaller, more stable form — likely once it locks into a wind band capable of holding it steady.
Researchers plan to keep a close eye on this giant vortex, because understanding the dynamics of Jupiter’s most famous storm could offer insight into the broader physics of weather itself. Studying how the Great Red Spot behaves not only helps scientists refine theories about hurricanes on Earth but could also improve how we predict atmospheric patterns on distant exoplanets.
Even after centuries of observation, Jupiter’s most iconic feature continues to surprise us — a swirling reminder that the universe is never as calm as it looks.
Nathalie Mayer
Journalist
Born in Lorraine on a freezing winter night, storytelling has always inspired me, first through my grandmother’s tales and later Stephen King’s imagination. A physicist turned science communicator, I’ve collaborated with institutions like CEA, Total, Engie, and Futura. Today, I focus on unraveling Earth’s complex environmental and energy challenges, blending science with storytelling to illuminate solutions.