NASA’s Juno spacecraft is continuing to deliver new information about Jupiter. The gas giant’s atmospheric winds are nothing like the atmospheric winds of Earth, the latest findings show. Rather, they run deeper into the atmosphere and have longer lifespans than anything on this planet.
“These astonishing science results are yet another example of Jupiter’s curve balls, and a testimony to the value of exploring the unknown from a new perspective with next-generation instruments,” says Scott Bolton, principal investigator of Juno, in a press release. “Juno’s unique orbit and evolutionary high-precision radio science and infrared technologies enabled these paradigm-shifting discoveries.”
Fast moving jet streams—narrow, variable bands of very strong wind—circle the planet constantly. These jet streams share some qualities with the ones we experience on Earth, the type that help planes break speed records, except they are 100 to 1,000 times stronger.
“Galileo viewed the stripes on Jupiter more than 400 years ago,” said Yohai Kaspi, Juno co-investigator and lead author of a new paper in Nature. “Until now, we only had a superficial understanding of them and have been able to relate these stripes to cloud features along Jupiter’s jets. Now, following the Juno gravity measurements, we know how deep the jets extend and what their structure is beneath the visible clouds. It’s like going from a 2-D picture to a 3-D version in high definition.”
Only on its 10th flyby of the planet, Juno has shown that jetstreams run from the very top of Jupiter’s clouds to a depth of 1,900 miles (3,000 kilometers). The spacecraft’s Jovian Infrared Auroral Mapper (JIRAM) proved especially useful in the most recent flyby. By focusing on infrared imaging, JIRAM can capture images of light emerging from deep inside Jupiter. It’s been probing the planet’s interior weather, going 30 to 45 miles (50 to 70 kilometers) below Jupiter’s cloud tops.
While most of the planet is surrounded by constantly changing wind, wind systems near the poles appears to be more stable—if no less violent. The north pole is dominated by a central cyclone surrounded by eight circumpolar cyclones with diameters ranging from 2,500 to 2,900 miles (4,000 to 4,600 kilometers). The south pole also has a central cyclone and it is surrounded by five cyclones with diameters ranging from 3,500 to 4,300 miles (5,600 to 7,000 kilometers) in diameter. These storms are arranged similarly to the mysterious north polar hexagon of storms on Saturn.
“Prior to Juno we did not know what the weather was like near Jupiter’s poles,” said Alberto Adriani, Juno co-investigator. “Now, we have been able to observe the polar weather up-close every two months. Each one of the northern cyclones is almost as wide as the distance between Naples, Italy and New York City—and the southern ones are even larger than that.”
What’s most striking about these cyclones is how tightly packed they are into Jupiter’s poles. They brush up right against each other and their spiral arms have even been shown to touch. Yet they never seem to merge.
“The question is, why do they not merge?” said Adriani. “We know with Cassini data that Saturn has a single cyclonic vortex at each pole. We are beginning to realize that not all gas giants are created equal.”
Juno’s 11th science pass will be on April 1. So far, Juno seems to be learning that everything about Jupiter, from its magnetic fields to its fierce winds, is even larger than realized.
