Jupiter's Lightning Is the Polar Opposite of Earth's

Scientists have known for decades that lightning slashes through the skies of gas giant Jupiter just as it does on Earth.

But new data has shown that lightning on Jupiter isn't quite as similar to Earth as previously thought. In some ways, it is actually the polar opposite.

NASA's Juno mission recently shed light on the giant cyclone clusters that collect at Jupiter's poles. These poles, scientists now know, are also a hub for intense lightning activity.

But on Earth, these blazing bolts cling to the equator.

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"Jupiter lightning distribution is inside out relative to Earth," Shannon Brown of NASA's Jet Propulsion Laboratory and lead author of a paper published Wednesday in Nature, said in a NASA statement.

"There is a lot of activity near Jupiter's poles but none near the equator."

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Lightning flashes on Jupiter in this artist's impression. NASA/JPL-Caltech/SwRI/JunoCam

Heat is behind this incredible choreography. The sun's rays that warm our own planet hit the equator first, and it is the warm, humid air rising at this band that drives its lightning.

Jupiter, on the other hand, sits much further away from our star and receives far less sunlight. The rays that do make it the gas giant, scientists believe, contribute to a stable upper atmosphere that traps warm air rising from the planet itself.

The poles don't have this source of warmth and stability, leaving their upper atmosphere untamed and stormy.

Although it clusters at the planet's spectacular poles, in other ways Jovian lightning is similar to our own. "In the data from our first eight flybys, [Juno] detected 377 lightning discharges," said Brown. "They were recorded in the megahertz as well as gigahertz range, which is what you can find with terrestrial lightning emissions."

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Scientists also measured similar rates of lightning on Jupiter as seen in storms on Earth. Researchers analysed more than 1,600 "whistlers"—emissions linked to the phenomena—captured by Juno in a Nature Astronomy paper also published Wednesday. They discovered lightning striking at a rate of about four flashes per second. This is far more than earlier spacecraft could detect.

"Our unique orbit allows our spacecraft to fly closer to Jupiter than any other spacecraft in history, so the signal strength of what the planet is radiating out is a thousand times stronger," Scott Bolton, principal investigator of Juno from the Southwest Research Institute, San Antonio, said.

"Our microwave and plasma wave instruments are state-of-the-art, allowing us to pick out even weak lightning signals from the cacophony of radio emissions from Jupiter."