Jupiter's Great Red Spot, which could swallow Earth, is changing colour, jiggling

Using Hubble's high-resolution imaging capabilities, astronomers created a time-lapse movie revealing the GRS's squiggly motion and size fluctuations.

In Short

• Hubble examined the size, shape, and subtle colour change of Great Red Spot
• Storm's core becomes brightest when the GRS reaches its maximum size
• Researchers have been tracking the GRS's shrinkage for the past decade

Nasa's Hubble Space Telescope has unveiled unexpected dynamics in Jupiter's iconic Great Red Spot (GRS), challenging long-held assumptions about the stability of this massive storm.

New observations conducted over 90 days from December 2023 to March 2024 show the GRS "jiggling like a bowl of gelatin," according to researchers.

The study, led by Amy Simon of Nasa's Goddard Space Flight Center and published in The Planetary Science Journal, provides unprecedented insights into the behaviour of the largest known storm in our solar system.

Using Hubble's high-resolution imaging capabilities, astronomers created a time-lapse movie revealing the GRS's squiggly motion and size fluctuations.

"We didn't expect to see the size oscillate. As far as we know, it's not been identified before," Simon explained. The storm was observed simultaneously squeezing in and out while accelerating and decelerating, a phenomenon that currently lacks hydrodynamic explanation.

The research team utilised Hubble to examine the GRS's size, shape, and subtle colour changes in detail.

Ultraviolet observations showed that the storm's core becomes brightest when the GRS reaches its maximum size during its oscillation cycle, indicating reduced haze absorption in the upper atmosphere.

Co-investigator Mike Wong from the University of California at Berkeley likened the GRS's behaviour to a sandwich, with the storm pushing against surrounding jet streams as it changes shape. This interaction keeps the GRS trapped at a southern latitude, unlike Neptune's dark spots that can drift more freely.

The study is part of Hubble's Outer Planet Atmospheres Legacy (OPAL) program, which annually monitors Jupiter and other outer planets. However, these specific observations were dedicated to the GRS, aiming to better understand the mechanisms of large-scale storms in a broader cosmic context.

Researchers have been tracking the GRS's shrinkage for the past decade and predict it will continue to decrease in size before stabilizing in a less elongated shape.

They hope future high-resolution images from Hubble will reveal more about the underlying causes of these newly observed oscillations.

This discovery not only advances our understanding of Jupiter's atmospheric dynamics but also provides valuable insights that could be applied to studying weather patterns on Earth and exoplanets.