Jupiter's Unusual Lightning Storms Look Very Much Like Earth's Lightning Storms

Wednesday, 06 June 2018 - 6:25PM
Space
Solar System
NASA
Wednesday, 06 June 2018 - 6:25PM
Jupiter's Unusual Lightning Storms Look Very Much Like Earth's Lightning Storms
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NASA/JPL-Caltech/SwRI/JunoCam
Despite its enormous size and gaseous composition being completely alien to Earth, at least Jupiter's lightning strikes look familiar to us Earthlings. Or, mostly familiar.

Jupiter is a very stormy planet, with its disappearing Great Red Spot being one giant storm, but lightning has always been a mystery that astronomers struggled with. We've known for ages that Jupiter has lightning - flashes of it were spotted all the way back in 1979 when Voyager 1 flew by - but some key signals that also accompany lightning were nowhere to be found.

Because while Voyager 1 had picked up low radio wave signals called "whistlers", but no higher-energy flashes called "sferics", and a lightning strike should be more than powerful enough to send out both. While it was long considered that Jovian lightning might be fundamentally different than Earth lightning, it turns out we just weren't looking close enough.




NASA's Juno probe, a much more recent spacecraft which has been orbiting Jupiter for several years and sending back lots of information and cool photos, was instructed to measure Jupiter's lightning more closely using its Microwave Radiometer Instrument tool. In the end, Juno picked up nearly 1,600 instances of lightning strikes which sent out energy all over the spectrum.

It had found its sferics, and the lightning's signatures were remarkably similar to Earth's after all. Shannon Brown, the lead author of the new paper on the subject and a scientist who works on Juno at NASA's Jet Propulsion Laboratory, said the following in an official statement from the space agency:

Opening quote
"No matter what planet you're on, lightning bolts act like radio transmitters - sending out radio waves when they flash across a sky. But until Juno, all the lightning signals recorded by spacecraft [Voyagers 1 and 2, Galileo, Cassini] were limited to either visual detections or from the kilohertz range of the radio spectrum, despite a search for signals in the megahertz range. Many theories were offered up to explain it, but no one theory could ever get traction as the answer.

"In the data from our first eight flybys, Juno's MWR detected 377 lightning discharges. They were recorded in the megahertz as well as gigahertz range, which is what you can find with terrestrial lightning emissions. We think the reason we are the only ones who can see it is because Juno is flying closer to the lighting than ever before, and we are searching at a radio frequency that passes easily through Jupiter's ionosphere."
Closing quote


However, it's not quite the same, and in a way, Jovian lightning is inverted. Earth experiences the majority of its lightning strikes closer to its equator, and almost none by its poles. Jupiter is the opposite, getting hit by lightning mostly around its poles, and experiencing almost none by its equator.

Since Juno's mission around Jupiter is likely to be extended, we'll hopefully learn more about the gas giant very soon. And as always, the probe should send back some cool photos as well.

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