We’ve known that Jupiter has lightning ever since the Voyager 1 spacecraft made its first flyby of the gas giant in 1979. But the origin of Jovian lightning has remained a mystery up until another famous flyby of Jupiter, this time by the Juno spacecraft.
Buzzing the largest planet in our solar system for the first time in 2016, the Juno probe also spotted the lightning on Jupiter, just like Voyagers 1 and 2, Galileo, and Cassini did before it. But the state-of-the-art science equipment on board the spacecraft allowed it to capture unique data on Jupiter’s lightning strikes, unraveling some of the mysteries that have been puzzling astronomers for almost 40 years.
In a pair of studies published on June 6, scientists from the Juno mission describe the radio emissions coming from Jovian lightning — dubbed “whistlers” on account of their descending whistling pitch, which sounds a lot like a falling bomb — as well as the novel frequencies at which they were picked up by the spacecraft still in orbit around the gas giant.
Just like in the famous GIF, Juno uncovered that lightning on Jupiter is very much the same as on Earth, while also being completely different than what we’re used to, revealed NASA.
One of the studies, featured in the journal Nature Astronomy, shows that lightning strikes on Jupiter “can be as frequent as on Earth,” lead author Ivana Kolmašová of the Czech Academy of Sciences in Prague told Space.com.
The research examined how often the Juno spacecraft detected lightning on Jupiter and found out that the probe’s Waves plasma and radio wave detector recorded more than 1,600 “whistlers.” That’s 10 times more than the number of signals picked up by Voyager 1.
According to NASA, this is the largest database of low-frequency radio emissions to ever be recorded from lightning sources on Jupiter.
“We succeeded in collecting the largest set of lightning detections known up to now,” Kolmašová told Gizmodo.
This bounty of data is attributed to the close range at which Juno surveilled the gas giant. The spacecraft came almost 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.
In addition, the Waves data uncovered peak rates of four lightning strikes per second — six times higher than the values recorded by Voyager 1 — which prove Jovian lightning has similar rates to those observed in terrestrial thunderstorms.
The other study, published in the journal Nature, unveiled that lighting on Jupiter produces not only kilohertz emissions, the singular radio range detected by Voyager 1 nearly four decades ago, but also gigahertz radio waves, just like lightning on Earth.
“No matter what planet you’re on, lightning bolts act like radio transmitters — sending out radio waves when they flash across a sky,” said lead study author Shannon Brown, who is a Juno scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Brown revealed that, during Juno’s first eight flybys of Jupiter, the spacecraft’s Microwave Radiometer instrument picked up 377 lightning blasts, which “were recorded in the megahertz as well as gigahertz range” — the same as “what you can find with terrestrial lightning emissions.”
William Kurth of the University of Iowa, who is study co-author on both papers, notes that the similarities found between lightning strikes on these two planets were a bit of a surprise.
“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 what makes Jovian lighting different from terrestrial lighting is its distribution. Unlike on Earth, lightning on Jupiter only seems to occur at high latitudes and is concentrated solely around the planet’s poles.
“There is a lot of activity near Jupiter’s poles but none near the equator. You can ask anybody who lives in the tropics — this doesn’t hold true for our planet,” says Brown.
Kurth also chimed in on the matter, explaining the main difference between lighting strikes on the two planets.
“That distribution of lightning is kind of upside-down from what we’d expect on Earth,” he said. “On Earth, thunderstorms tend to cluster around low latitudes, and on Jupiter, it’s the other way around.”
At the same time, it turns out that Jovian lightning is more frequent in the northern hemisphere than in the southern one, although scientists don’t have an explanation yet as to why this happens.
But the findings did reveal something important about Jupiter’s atmospheric composition and circulation. Because the gas giant orbits the sun five times farther than Earth does, it gets 25 times less sunlight than our planet.
This means that the sun’s rays are powerful enough to heat Jupiter’s equator, which creates stability in the region’s upper atmosphere and prevents warm air from rising up from within. (Jupiter’s atmosphere derives the majority of its heat from within the planet itself, notes NASA.)
But the poles are a different story and don’t have the same atmospheric stability because their upper atmosphere doesn’t receive the same amount of heat. Therefore, warm gases from the planet’s interior are rising up at the poles, creating the recipe for lighting.
Juno is bound to make its 13th flyby of Jupiter on July 16. Perhaps the spacecraft will be able to find answers for the remaining questions when it swoops over the planet’s mysterious cloud tops once more.
Although this upcoming enterprise was slated to mark the end of the Juno mission, NASA might allow the spacecraft to keep doing its magic for an additional three years, the Inquisitr reported yesterday.