Jupiter's Great Red Spot is changing in ways “never identified before”

A huge storm has been raging on Jupiter for centuries, and for the most part it looks very serious. A new series of detailed images, however, has revealed that the famous red cyclone can become a bit wavy, taking on different shapes and sizes in a short period of time.

Astronomers used the Hubble Space Telescope to observe Jupiter's Great Red Spot (GRS) from December 2023 to March 2024, and watched the massive storm change size over the 90-day period. The reason behind this unexpected shape change is unknown, but it revealed that the famous red storm is not as stable as it seemed. The results of the Hubble observations are detailed in a study published Wednesday in The Journal of Planetary Science.

Using Hubble observations, the team of astronomers behind the new study measured the size, shape, brightness, color and vorticity of the Great Red Spot over a complete oscillation cycle. The combined images act as a time-lapse of the storm's changing behavior, revealing its famous red eye varying in size, while its core grows brighter as the Great Red Spot reaches its greatest level during the 90-day cycle.

“This is actually the first time we've gotten proper imaging cadence from the GRS. With Hubble's high resolution, we can say that the GRS is definitely moving in and out while moving faster and slower,” Amy Simon, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, lead author of the new study. , said in a statement. “Although we knew that its movement varies slightly along its length, we did not expect to see its size fluctuate as well. As far as we know, it has not been identified before.”

The Red Spot is the largest known storm in the solar system, occupying one-sixth the diameter of Jupiter itself. It's so big it could swallow the Earth in its cloudy oval, measuring almost twice the size of our planet. When it was first observed, the Great Red Spot stretched 39,000 kilometers, but it has been shrinking ever since. Today, the storm stretches 16,350 kilometers (10,159 miles) and has become more rounded.

Hubble has been observing the shrinking of the Great Red Spot for the past 10 years, and the team responsible for the study predicts that it will become more stable as it shrinks in size. “Right now it is overfilling its latitude range in relation to the wind field. Once it shrinks within that range, the winds will actually hold it in place,” Simon said.

Unlike hurricanes on Earth, the Great Red Spot rotates counterclockwise, suggesting it is a high-pressure system. However, understanding the mechanics behind Jupiter's ancient storm could help scientists better understand hurricanes on Earth in a broader cosmic context, as well as meteorology on other planets.

The Great Red Spot is known to change size, color and shape, but the new observations reveal many changes from day to day. “As it speeds up and slows down, the GRS is pushing windy jet streams to the north and south,” said Mike Wong, a researcher at the University of California at Berkeley and co-author of the study, in a statement. . “It’s similar to a sandwich where the slices of bread are forced to stick out when there’s too much filling in the middle.”

Although the iconic storm was first sighted in 1664, scientists are still surprised by its mysterious and strange behavior that, until now, they have been unable to explain. There's still more to learn about Jupiter's erratic storm, and fortunately, Hubble will remain vigilant.