Jupiter is a planet of storms, but also a planet of mysteries. How can a stretch of gas giant spinning with cyclones also be a desert?
Expect anything from a famous (or infamous) planet for things like the Red Sea Spot and a strange, stormy pentagon that could pass for a UFO formation. Jupiter’s “hot spots” (first seen by NASA’s Galileo spacecraft) have been an enigma that has remained in the dark until now. Now, the Juno probe had a different look. It was previously thought to be local deserts. What Juno sent back suggests that these hot spots, which deceptively glow in the infrared, may not be as different from the rest of Jupiter – at least the part of Jupiter where it exists. This entire region of the planet is a cosmic desert.
It turned out that Galileo was upset without even knowing it. As it sank into one of the hotspots in Jupiter’s northern equatorial region and discovered how dry and windy it was, astronomers back on Earth automatically assumed that each hotspot was its own localized desert. They go much deeper and further, if you ask Juno’s co-investigator, Tristan Guillot.
“We see that the whole area has a low abundance of ammonia and we realize that the hot spots could only be cleared in the clouds,” Guillot told SYFY WIRE. “The storms we see in JunoCam images must have carried both ammonia and deep water, not only where the hot spots are, but everywhere around these latitudes.”
Juno revealed that the hot spots have something to do with the cracks in Jupiter’s thick clouds, which could allow the probe to look into the depths of the Jovian atmosphere, where it is hotter and drier than anywhere else. Another thing Juno saw was that a phenomenon known as shallow lightning was fueled by these desert storms. For lightning to form, there must be a liquid in the atmosphere to increase the particles and transfer the charge. Superficial lightning is so strange because it can occur at atmospheric levels that are too cold to keep the water liquid. This is where ammonia comes in. If you mix water and ammonia, you can keep the water liquid so that the lightning ignites even in such a deep freeze.
It becomes more unknown from here. Juno’s microwave instrument can no longer see water and ammonia when they join forces. Not only that, but they also produce so-called foreign hailstones. The gigantic storms that appear from the condensation of water much deeper into the atmosphere give rise to the formation of fungi. A shallow flash literally illuminates where these storms form, which could ultimately help to understand how heat moves around the planet. If humans could actually live on Jupiter, shallow lightning would be a frightening sign of incoming diseases.
“Mushballs reveals that Jupiter’s atmosphere is quite different than expected,” Guillot said. “Instead of being unstable and homogeneously mixed convective, we now imagine that the deep atmosphere is stable on average, with an increase in the abundance of ammonia and water as you go deeper.”
When the fungi grow heavy enough, they fall into the atmosphere and leave behind a region almost devoid of ammonia and water. They must melt and evaporate for ammonia and water to become gas again and therefore once again visible to Juno. Guillot sees the behavior of ammonia and water in Jovian storms as analogous to the slow addition of milk to water without mixing liquids. The milk will sink to the bottom of the glass just like water and ammonia will sink through Jupiter’s atmosphere during a storm. The difference is that, unlike a glass, Jupiter has no bottom – or surface that we know about. How much ammonia can be submerged and water is something that will need to be further investigated. It could sink hypothetically to the end. Nobody knows.
What the Juno team needs to do now is figure out how effective mushroom formation really is and how to apply it to Juno data. The probe has already allowed the Juno team to get an idea of how much water hides deep in Jupiter’s atmosphere. For a more accurate estimate, they will need to understand how water makes its way to the depths of other regions. Juno can demystify this as he gradually moves to the north pole of Jupiter, which is believed to have very different properties, which could tell Guillot and his colleagues even more about Jovian’s bizarre weather.
“Our research has far-reaching implications,” he said. “All the planets in our solar system, as well as the exoplanets, have very light atmospheres. The same process could occur when the elements condense in these atmospheres. Understanding what is happening on Jupiter will be essential when we apply our models to interpret the exoplanetary spectra to be measured soon by the James Webb Space Telescope. “