Now to Jupiter, where scientists have been using data from NASA’s Juno spacecraft to solve mysteries left from analysis of Galileo data taken 25 years ago.

Think about how you imagine Jupiter from the images we have. Cloudy. Dense. Gassy. So unlike Earth, it’s honestly hard to imagine. The Galileo mission sent a probe into Jupiter to try and understand just how different the giant planet is, and the results were so surprising that they thought it was an anomaly. Basically, they thought the probe had gone into a “hot spot”, something as uncommon on Jupiter as it is here on Earth.

It turns out, though, that what they thought was a patch of hot, dense gas – localized atmospheric “deserts” that traverse the gas giant’s northern equatorial region – is actually just how the entire northern equatorial belt is. Per the press release: The implication is that the hot spots may not be isolated “deserts,” but rather, windows into a vast region in Jupiter’s atmosphere that may be hotter and drier than other areas. Juno’s high-resolution data show that these Jovian hot spots are associated with breaks in the planet’s cloud deck, providing a glimpse into Jupiter’s deep atmosphere.

This dry atmosphere may be the cause of the shallow lightning and mushballs reported on earlier this year. Tristan Guillot, a Juno co-investigator, explains: High up in the atmosphere, where shallow lightning is seen, water and ammonia are combined and become invisible to Juno’s microwave instrument. This is where a special kind of hailstone that we call ‘mushballs’ are forming. These mushballs get heavy and fall deep into the atmosphere, creating a large region that is depleted of both ammonia and water. Once the mushballs melt and evaporate, the ammonia and water change back to a gaseous state and are visible to Juno again.

So. Jupiter’s atmosphere is drier and hotter than previously thought. And we still have more to learn and understand.

More Information

NASA JPL press release