"No matter what planet you're on, lightning bolts act like radio transmitters - sending out radio waves when they flash across a sky", Shannon Brown, Juno scientist at NASA's Jet Propulsion Laboratory, said in a news release.
According to NASA, this is the largest database of low-frequency radio emissions to ever be recorded from lightning sources on Jupiter. When NASA sent its Voyager 1 spacecraft on its trip through our Solar System, its flyby of Jupiter revealed that Jupiter does indeed have lightning, but it wasn't producing the same kinds of radio signals that scientists are familiar with from lightning here on Earth. Many theories tried to explain the phenomenon, but none of them could ever visualize traction as the answer.
The $1.1 billion Juno mission has been extended through at least July 2021, NASA officials announced yesterday (June 6). This plan no longer holds, and NASA will allow the spacecraft to orbit Jupiter three more years to enable the probe to meet its goal. "In the data from our first eight flybys, [Juno] detected 377 lightning discharges", said Brown. The spacecraft came nearly 50 times closer to the planet than Voyager 1 ever did, flying "closer to Jupiter than any other spacecraft in history", states Juno's principal investigator Scott Bolton from the Southwest Research Institute in San Antonio, who was involved in both studies.
"Given the very pronounced differences in the atmospheres between Jupiter and Earth, one might say the similarities we see in their thunderstorms are rather astounding."
But the team also noted something not like Earth at all: Jupiter's lightning activity is clustered around its poles. They think that, because Jupiter's atmosphere is stable near its equator thanks to warmth from the Sun, the lightning is forming in the much less stable air rising near its poles from within the planet.
This causes warm most air to rise most freely at the equator, powering huge lightning storms.
Jupiter is about 25 times farther from the sun than Earth, meaning that, unlike our planet, it gets the majority of its heat from itself.
"This will help us better understand the composition, general circulation and energy transport on Jupiter". The dataset of in excess of 1,600 signs, gathered by Juno's Waves instrument, is right around 10 times the number recorded by Voyager 1. In another paper related to the findings from Juno, the researchers noted that the spacecraft's Waves instrument detected six times more lightning than Voyager, with as many as four lightning strikes per second, just like the rate observed on Earth.
Dr. Scott Bolton concludes, "These discoveries could only happen with Juno". "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". The signals were showing up in the kilohertz band of the electromagnetic spectrum, but not the megahertz range as is the case with Earth lightning.
The decision to fund the Juno mission through fiscal year 2022 was made after an "independent panel of experts" ruled that it was on track to "achieve its science objectives and is already returning spectacular results".
"Lightning at Jupiter can be as frequent as on Earth", lead author of the study Ivana Kolmašová, of the Czech Academy of Sciences in Prague, confirmed.