Jupiter's birthmark is an unbelievably huge storm that’s mysteriously crimson red in color. It looks like a bloodshot cycloptic eye staring back at Earth. The anticyclone churns along a southern mid-latitude cloud belt and has survived in Jupiter's turbulent atmosphere for at least 150 years. What’s mind-numbing is that the Great Red Spot (GRS) is big enough to swallow our entire planet, making it the largest storm in the solar system.

Astronomers need Hubble's keen vision to keep an eye on the GRS's behavior, like a weatherman watching a spinning hurricane. This is done only once per year under the Outer Planet Atmospheres Legacy program (OPAL), but a new program has enabled Hubble to capture eight views of the spot over a 90-day period. And there are always new surprises.

For 90 days between December 2023 and March 2024, a collection of Hubble photos reveal that the GRS is not as stable as it might look. Its elliptical shape can change dimensions – looking like a slightly skinnier or fatter red oval. This shape-shifting is unexpected and unexplained. But in hindsight, this might not be a total surprise considering that Jupiter’s atmosphere is ever-changing with dynamic winds. It's like trying to predict the exact motion of a swirl of creamer poured into a cup of coffee. Does the meteorology on giant planets around other stars have their own immense storms? Hubble's detailed look at Jupiter might offer new clues.