![]() "We're continuing to look for more telltale signs of elves and sprites every time Juno does a science pass," said Giles. Since then, it has made 29 science flybys of the gas giant, each orbit taking 53 days. And UVS recorded that the spectra of the bright flashes were dominated by hydrogen emissions.Ī rotating, solar-powered spacecraft, Juno, arrived at Jupiter in 2016 after making a five-year journey. 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. 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. The occurrence of sprites and elves at Jupiter was predicted by several previously published studies. "But on Jupiter, the upper atmosphere mostly consists of hydrogen, so they would likely appear either blue or pink." "On Earth, sprites and elves appear reddish in color due to their interaction with nitrogen in the upper atmosphere," said Giles. They, too, brighten the sky for mere milliseconds but can grow larger than sprites - up to 200 miles (320 kilometers) across on Earth. 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. 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).Īlmost 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. Named after a mischievous, quick-witted character in English folklore, sprites are transient luminous events triggered by lightning discharges from thunderstorms far below. ![]() The more our team looked into it, the more we realized Juno may have detected a TLE on Jupiter." "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. Elves were discovered in 1992 by a low-light video camera on the Space Shuttle."UVS was designed to characterize Jupiter's beautiful northern and southern lights," said Giles, a Juno scientist and the lead author of the paper. Scientists believe elves result when an energetic electromagnetic pulse extends up into the ionosphere. They last less than a thousandth of a second, and occur above areas of active cloud to ground lightning. ![]() Blue jets last a fraction of a second and have been witnessed by pilots.Įlves are rapidly expanding disk-shaped regions of glowing that can be up to 300 miles across. ![]() They extend up in narrow cones fanning out and disappearing at heights of 25-35 miles. They are rarely seen with the human eye, so they are most often imaged with highly sensitive cameras.īlue jets emerge from the top of the thundercloud, but are not directly associated with cloud-to-ground lighting. Because sprites are not very bright, they can only be seen at night. Sprites are mostly red and usually last no more than a few seconds, and their shapes are described as resembling jellyfish, carrots, or columns. They can extend up to 60 miles from the cloud top. They usually happen at the same time as powerful positive CG lightning strokes. Red Sprites can appear directly above an active thunderstorm as a large but weak flash. ![]() The most common TLE's include red sprites, blue jets, and elves. Large thunderstorms are capable of producing other kinds of electrical phenomena called transient luminous events (TLE's). ![]()
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