Jupiter’s Great Red Spot is healthy despite looking like it’s dying

Jupiter red spot

Jupiter’s Red Spot is in better shape than we thought

NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill/CC BY 3.0

Jupiter’s giant storm, the Great Red Spot, may not be dying any time soon. It seems to have been unravelling for decades, but this is probably down to the movement and shredding of clouds rather than a sign that the storm is abating.

Concerns have been mounting that the Great Red Spot might disappear. Once it was big enough for almost three Earth-sized planets to fit inside it – now it can hold little more than one. Although we know the iconic storm has been shrinking since 1878, the pace of this seems to have picked up since 2012, leading to reports that it could be nearing its demise.

What’s more, photos of Jupiter captured earlier this year by the spacecraft Juno showed red “flakes” measuring 100,000 kilometres across breaking off from the Great Red Spot.

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But this flaking isn’t actually a sign of the storm breaking apart and dying, says Philip Marcus at the University of California, Berkeley, who presented the findings today at a meeting of the American Physical Society in Seattle.

The health of the Great Red Spot has been previously inferred from images of the clouds that sit above its central swirling vortex – shrinking clouds are thought to indicate a shrinking storm. But although the clouds probably affect the vortex, they aren’t crucial to maintaining the storm itself, says Marcus.

Using computer models, he and his colleagues found that the flaking captured by Juno was in fact the effects of a rare event: cyclones that are common in Jupiter’s atmosphere had collided with lumps of cloud that hadn’t yet been pulled into the storm as they passed by. The impact “shattered” the clouds, which appear red because they sit above the storm and are therefore exposed to more of the sun’s UV radiation. This gives the impression that parts of the Great Red Spot are coming apart.

Marcus says he was surprised by how easy it was to simulate the flaking, which “cried out for explanation”.

“It’s wonderful to see serious attempts at numerical simulations being brought to bear on this complex topic,” says Leigh Fletcher at the University of Leicester, UK. We should be careful about making assumptions based on photos alone when we still don’t fully understand the storm’s environment, he says.

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