An instrument on the spacecraft may have detected transient luminous events – bright flashes of light in the gas giant’s upper atmosphere.
New results from NASA’s Juno mission at Jupiter suggest that
either “sprites” or “elves” could be dancing in the upper
atmosphere of the solar system’s largest planet. It is the first time these
bright, unpredictable and extremely brief flashes of light – formally known as
transient luminous events, or TLE’s – have been observed on another world. The findings were published on Oct. 27, 2020, in the Journal of
Geophysical Research: Planets.
Scientists predicted these bright, superfast flashes of
light should also be present in Jupiter’s immense roiling atmosphere, but their
existence remained theoretical. Then, in the summer of 2019, researchers working
with data from Juno’s ultraviolet spectrograph
instrument (UVS) discovered something unexpected: a bright, narrow
streak 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 the lead author of the paper. “But we discovered UVS images that not
only showed Jovian aurora, but also a bright flash of UV light over in the
corner where it wasn’t supposed to be. The more our team looked into it, the
more we realized Juno may have detected a TLE on Jupiter.”
Brief and Brilliant
Named after a mischievous,
quick-witted character in English folklore, sprites are transient
luminous events triggered by lightning
discharges from thunderstorms far below. On Earth, they occur up to 60
miles (97 kilometers) above intense, towering thunderstorms and brighten a region of the sky tens of miles across, yet
last only a few milliseconds (a fraction of the time it takes you to blink an eye).
Almost resembling a jellyfish, sprites feature
a central blob of light (on Earth, it’s 15 to 30 miles, or 24 to 48 kilometers,
across), with long tendrils
extending both down toward the ground and upward. Elves (short for Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources) appear as a flattened disk glowing in Earth’s
upper atmosphere. They, too, brighten the sky for mere milliseconds but can
grow larger than sprites – up to 200 miles (320 kilometers) across on Earth.
Their colors are distinctive as well. “On
Earth, sprites and elves appear reddish in color due to their interaction with
nitrogen in the upper atmosphere,” said Giles. “But on Jupiter, the
upper atmosphere mostly consists of hydrogen, so they would likely appear
either blue or pink.”
With three giant blades stretching out some 66 feet (20 meters) from its cylindrical, six-sided body, the Juno spacecraft is a dynamic engineering marvel, spinning to keep itself stable as it makes oval-shaped orbits around Jupiter. View the full interactive experience at Eyes on the Solar System.
Location, Location, Location
The occurrence of sprites and
elves at Jupiter was predicted by several previously published studies. Synching
with these predictions, the 11 large-scale bright events Juno’s UVS instrument has detected occurred in a region where lightning thunderstorms are known to form. Juno
scientists could also rule out that these were simply mega-bolts of lightning
because they were found about 186 miles (300 kilometers) above the altitude
where the majority of Jupiter’s lightning forms – its water-cloud layer. And UVS
recorded that the spectra of the bright
flashes were dominated by hydrogen
A rotating, solar-powered spacecraft, Juno, arrived
at Jupiter in 2016 after making a five-year journey. Since then, it has made 29
science flybys of the gas giant, each orbit taking 53 days.
“We’re continuing to look for more telltale signs of
elves and sprites every time Juno does a science pass,” said Giles. “Now
that we know what we are looking for, it will be easier to find them at Jupiter
and on other planets. And comparing sprites and elves from Jupiter with those
here on Earth will help us better understand electrical activity in planetary
More About the Mission
JPL, a division of Caltech in Pasadena, California, manages the
Juno mission for the principal investigator, Scott Bolton, of the Southwest
Research Institute in San Antonio. Juno is part of NASA’s New Frontiers
Program, which is managed 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 spacecraft.
More information about Juno is available at:
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News Media Contact
Jet Propulsion Laboratory, Pasadena, Calif.
NASA Headquarters, Washington
202-672-4780 / 202-358-0668
Southwest Research Institute, San Antonio
Source: Jet Propulsion Laboratory