Juno data suggests “sprites” or “elves” frolicking in Jupiter’s atmosphere –...

Scientists predicted that these bright, super-fast flashes of light should also be present in Jupiter’s immense atmosphere, but their existence remained theoretical. In the summer of 2019, researchers working with data from Juno’s ultraviolet spectrograph (UVS) discovered something unexpected: a bright, narrow strip of ultraviolet emission that disappeared in a flash.

“UVS was designed to characterize Jupiter’s beautiful northern and southern lights,” said Giles, a Juno scientist and lead author of the paper. “But we discovered UVS images that not only showed the Jupiter aurora, but also a bright flash of UV light in the corner where it shouldn’t be. The more our team looked at it, the more we realized that Juno may have recognized this. ”A TLE on Jupiter. ”

Short and brilliant

Sprites, named for a mischievous, quick-witted character in English folklore, are transient glowing events triggered by lightning discharges from thunderstorms far below. On Earth, they occur up to 60 miles over intense, towering thunderstorms and illuminate a region of the sky tens of kilometers in diameter, but only last a few milliseconds (a fraction of the time it takes to blink an eye ). .

Sprites are almost like a jellyfish and have a central spot of light (15 to 30 miles or 24 to 48 kilometers in diameter on Earth) with long tendrils that extend both down to the ground and up. Elves (short for light emission and very low-frequency disturbances due to electromagnetic pulse sources) appear as a flattened disc that glows in the upper atmosphere of the earth. They also light up the sky for just milliseconds, but can be larger than sprites – up to 320 kilometers wide on Earth.

Their colors are also unmistakable. “On Earth, sprites and elves appear reddish due to their interaction with nitrogen in the upper atmosphere,” said Giles. “But on Jupiter, the upper atmosphere is mostly hydrogen, so it will likely appear either blue or pink.”

Location, location, location

The appearance of sprites and elves at Jupiter has been predicted by several previously published studies. Consistent with these predictions, the 11 large area bright events detected by the Juno UVS instrument occurred in a region known to be lightning storms. Juno scientists were also able to rule out that they were just mega-lightning bolts, as they were found about 300 kilometers above the height at which most of the Jupiter lightning bolt forms – its water cloud layer. And UVS recorded that the spectra of the bright flashes were dominated by hydrogen emissions.

A rotating, solar-powered spacecraft, Juno, arrived at Jupiter in 2016 after a five-year journey. Since then, the gas giant has made 29 scientific flybys, each orbit lasting 53 days.

“We look for telltale signs of elves and sprites every time Juno takes a science pass,” Giles said. “Now that we know what we are looking for, it will be easier to find them on Jupiter and on other planets. If we compare the Sprites and Elves of Jupiter with those here on Earth, we can better understand the electrical activity in planetary atmospheres. ”

More about the mission

JPL, a division of Caltech in Pasadena, California, administers the Juno mission for Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers program, administered at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built and operates the spaceship.

For more information on Juno, visit: