We only had a skin-deep look at Jupiter before the Juno spacecraft began orbiting the planet in 2016 and the measurements the NASA mission has taken reveal unexpected information about its deep interior
28 October 2021
Jupiter’s Great Red Spot, the colossal storm that has raged in the planet’s atmosphere for centuries, is even deeper than researchers expected. According to new data from NASA’s Juno spacecraft, which has been orbiting Jupiter since 2016, the giant planet’s insides aren’t as well mixed as we thought.
The Juno spacecraft used microwave readings and measurements of the density of material inside Jupiter to peer deep under its clouds.
“This is the deepest look we’ve had into a giant planet,” says Juno team leader Scott Bolton at the Southwest Research Institute in Texas. “Prior to this, we’ve just seen skin-deep.”
The measurements showed that the Great Red Spot extends far beneath the planet’s clouds, which sit about 240 kilometres below the top of the atmosphere, with the storm perhaps reaching a depth of 500 kilometres. Two smaller storms were also found to have roots hundreds of kilometres deep, and the jet streams that make up the bands of colour at the top of Jupiter’s atmosphere extend as deep as 3000 kilometres.
Researchers expected these depths to be fairly homogeneous on Jupiter. “Generally, the idea is that once you drop below where the sunlight reaches, below where the water condenses into clouds, it’s all vapour,” says Bolton. “Most people expected that it would be well mixed, so you wouldn’t get much weather going on down there.”
The fact that the roots of Jupiter’s storms go so deep indicates that the layers of the planet’s atmosphere are more interconnected than we realised. “In hindsight, it makes sense that the layers are not completely isolated from each other, because it’s a giant ball of gas,” says Bolton.
There is more work yet to be done to figure out how the various layers are connected, he says – and Juno still has more storms to observe in the remaining years of its mission, which should help.
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