Jupiter’s Great Red Spot has been shrinking, but research shows that this does not necessarily mean the famous storm is dying.
At November’s annual meeting of the American Physical Society, UC Berkeley mechanical engineering professor Philip Marcus presented research co-authored by researchers at UC Berkeley, Rice University and UCSF, which provided a new explanation for the recently observed shrinkage of Jupiter’s famous Great Red Spot.
The Great Red Spot was first observed by astronomers in the 1600s and has been consistently recorded since the early 1800s. In 1979, astronomers showed that Jupiter’s Great Red Spot had shrunk to half the size it was in the 1800s, prompting concerns over the “health” of the spot, according to Marcus.
This year, amateur astronomers reported observations that the Great Red Spot was “unraveling,” Marcus said, with large “flakes” of the clouds falling away. These observations inspired news stories warning that the Great Red Spot may be in the process of dying.
Marcus and the other researchers who worked on this study were unconvinced, however.
“Just because the clouds change and shrink, doesn’t mean the underlying engine of the vortex is changing or shrinking,” Marcus said.
Using 3D simulations of Jupiter’s vortices, the researchers found that parts of Jupiter’s Great Red Spot flaking off can be explained by the storm’s interactions with other storms in Jupiter’s atmosphere. The Great Red Spot is an anticyclone, which rotates in the opposite direction of the planet’s spin and is covered in clouds, but Marcus’ previous research has shown that Jupiter’s atmosphere also contains many other unobservable and cloudless cyclones which rotate in the same direction as the planet’s spin. According to Marcus, these cyclones interact with and push the observable anticyclones.
The Great Red Spot has also frequently been observed to eat “small vortices like itself, which circulate around it then are digested,” Marcus said. As the small vortex is digested, it may leave “undigested lumps” on the edge of the Great Red Spot.
The observed flakes coming off of the spot can be explained by these two weather phenomena, according to Marcus. The simulations run by the researchers show that the observed flakes coming off could have been cloud lumps left by the spot eating other anticyclones, which were shattered away from the central vortex when the Great Red Spot came into contact with an unobservable cyclone.
The Great Red Spot has most likely flaked off cloud chunks before, according to Aidi Zhang, a campus doctoral student who contributed to the research, but this atmospheric change went unobserved. Because of the increasing number of amateur astronomers who watch Jupiter every day, people are now able to record more of these small changes in Jupiter’s atmosphere.
“To paraphrase Mark Twain, the reports of the (Great Red Spot’s) death are greatly exaggerated, or at least premature,” Marcus said in a statement.