This image of Jupiter from NASA’s James Webb Space Telescope in July 2022 shows stunning detail of … [+]
Look at any image of Jupiter and one feature is hard to ignore – its “Great Red Spot”, a massive storm erupting near its equator.
It is so iconic that it is unusual to see an image of Jupiter without it, despite the fact that Jupiter rotates once in just under 10 hours.
However, that point is shrinking. Scientists now think they know why.
Rolled oval
A storm about the diameter of Earth, the Great Red Spot, is in Jupiter’s southern hemisphere and has been erupting since 1831. A swirling, red-orange high-pressure oval more than 10,000 miles wide, it has winds 425 miles per hour blowing counterclockwise.
This makes it not a cyclone but an anticyclone.
There are many unknowns about this massive storm. Astronomers don’t know how old it is, why it formed, or why it’s red. What they do know is that it has gotten smaller over the last 100 years, especially in the last 50 years.
Smaller storms
Now, new research is revealing why the Great Red Spot is shrinking. Revealed in a paper published in the journal Icarus, a series of 3D simulations of the Great Red Spot and Jupiter’s atmosphere included interactions between it and smaller storms. The results suggest that the presence of other storms strengthens the Great Red Spot, causing it to grow larger. Without them, it shrinks.
“We found through numerical simulations that by feeding the Great Red Spot a diet of smaller storms, as are known to occur on Jupiter, we could modify its size,” said Caleb Keaveney, lead author and Ph.D. student at the Yale Graduate School of Arts and Sciences.
Earth’s weather
The work has implications for predicting extreme weather on Earth. High-pressure systems in the westerly jet streams that circulate through Earth’s midlatitudes—a major factor in heat waves and droughts—can be associated with high-pressure eddies and anticyclones.
“Our study has compelling implications for weather events on Earth,” Keaveney said. “Interactions with nearby weather systems have been shown to support and amplify heat domes, which motivated our hypothesis that similar interactions on Jupiter could support the Great Red Spot. In validating this hypothesis, we provide additional support for this understanding of heat domes on Earth.
Potato shaped moon
In May, Juno returned an image of the moon Amalthea above Jupiter’s “Great Red Spot.” A small potato-shaped moon with a radius of just 52 miles (84 kilometers), Amalthea is the reddest object in the solar system, according to NASA. This may be because it emits more heat than it receives from the sun, perhaps because electric currents are induced in the moon’s core.
However, since Amalthea takes less than half a day to orbit Jupiter, its temperature may be due to tidal stresses caused by Jupiter’s gravity, which creates a lot of friction and heat within it.
Planetary scientists had not seen an image of the moon since 2000 when NASA’s Galileo spacecraft discovered craters, hills and valleys on Amalthea.
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