NASA‘s Juno spacecraft has captured electric blue ‘sprites’ and ‘elves’ dancing in Jupiter’s atmosphere.
Such transient luminous events occur on Earth during a thunderstorm, but these are the first to be observed on another world.
The bright, unpredictable flashes of lights typically form on our planet about 60 miles above large thunderstorms, creating flares that last just milliseconds.
The flashes, which are deemed sprites, resemble a jellyfish with long tendrils flowing down toward the ground, and elves appear as a flattened glowing disc that can stretch up to 200 miles across the sky.
Juno scientists spotted the cosmic displays 186 miles above the altitude where the majority of the gas giant’s lightning forms -its water-cloud layer.
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NASA’s Juno spacecraft has captured electric blue ‘sprites’ and ‘elves’ dancing in Jupiter’s atmosphere. Juno scientists spotted the cosmic displays 186 miles above the altitude where the majority of the gas giant’s lightning forms -its water-cloud layer
Juno’s ultraviolet spectrograph instrument (UVS) detected the transient luminous events( TLE), which appeared as a bright, narrow streak of ultraviolet emission that disappeared in a flash.
Rohini S. Giles, lead study author and Juno planetary scientist, said: ‘UVS was designed to characterize Jupiter’s beautiful northern and southern lights.’
‘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.’
The occurrence of sprites and elves on Jupiter were predicted by several previously published studies, but Juno has confirmed these theories to be true.
The craft capture 11 large-scale bright events 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 above the altitude where the majority of Jupiter’s lightning forms – its water-cloud layer.
Jupiter’s hydrogen-rich atmosphere would likely make sprites appear blue, while they glow red on Earth (illustration)
And UVS recorded that the spectra of the bright flashes were dominated by hydrogen emissions.
Sprites, which are named after the mischievous English folklore, were first documented on Earth in 1990.
These objects form up to 60 miles above violent thunderstorms and can light up the night sky tens of miles across, but the brilliant display lasts only a few milliseconds.
The typically grow a bright red on Earth, but on Jupiter the appear as a glowing blue.
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.
These occur high above energetic cloud-to-ground lightning of positive or negative polarity, and were confirmed in 1992 by a camera on the International Space Station.
Just like their fellow sprites, these last just milliseconds but can grow larger – up to 200 across on Earth.
‘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.’
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
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 atmospheres.’
How NASA’s Juno probe to Jupiter will reveal the secrets of the solar system’s biggest planet
The Juno probe reached Jupiter in 2016 after a five-year, 1.8 billion-mile journey from Earth
The Juno probe reached Jupiter on July 4, 2016, after a five-year, 1.8 billion-mile (2.8bn km) journey from Earth.
Following a successful braking manoeuvre, it entered into a long polar orbit flying to within 3,100 miles (5,000 km) of the planet’s swirling cloud tops.
The probe skimmed to within just 2,600 miles (4,200 km) of the planet’s clouds once a fortnight – too close to provide global coverage in a single image.
No previous spacecraft has orbited so close to Jupiter, although two others have been sent plunging to their destruction through its atmosphere.
To complete its risky mission Juno survived a circuit-frying radiation storm generated by Jupiter’s powerful magnetic field.
The maelstrom of high energy particles travelling at nearly the speed of light is the harshest radiation environment in the Solar System.
To cope with the conditions, the spacecraft was protected with special radiation-hardened wiring and sensor shielding.
Its all-important ‘brain’ – the spacecraft’s flight computer – was housed in an armoured vault made of titanium and weighing almost 400 pounds (172kg).
The craft is expected to study the composition of the planet’s atmosphere until 2021.