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". The spacecraft not only snapped a photo of a lightning storm but also detected radio waves from the strikes. 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.
"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 of NASA's Jet Propulsion Laboratory and the lead author of the latest work said in a statement. Now, reports Charles Q. Choi at Space.com, the Juno spacecraft has taken its own measurements and found that lightning on Jupiter is not as unusual as we once thought.
An artist's impression of lightning bolts in the northern hemisphere of Jupiter.
This discovery was backed up in the second article, published by a team of scientists of the Academy of Sciences of the Czech Republic, which presented the most famous record collection of lightning with a giant planet. The majority of Jupiter's zaps take place near the poles. "Many theories were offered up to explain it, but no one theory could ever get traction as the answer".
Researchers detected more than 1,600 instances of lightning on Jupiter gathered via a phenomenon called "whistlers". Also, 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.
Juno is unraveling Jupiter's mysteries. With additional funding through fiscal year 2022, the unmanned spacecraft will have additional time to complete its primary science observations of the gas giant and its magnetic field, with the extra time required due to the spacecraft taking longer than planned orbits. Heat rising from the planet creates roiling convection currents that lead to storms and lightning.
Lightning on Jupiter is believed to originate from electrical interactions between water droplets and ice particles, similar to how lightning happens on Earth.
"These findings could help to improve our understanding of the composition, circulation and energy flows on Jupiter", said Brown. Before Juno - which has been orbiting Jupiter since the summer of 2016 and has more sensitive instruments than older probes - the lightning on Jupiter was only recorded in the kilohertz range. This is much higher than Voyager previously detected and similar to rates found on Earth. Because the gas giant orbits the sun five times farther than Earth does, it gets 25 times less sunlight than our planet.
NASA has extended the duration of its Juno space probe mission until 2021.
"This is great news for planetary exploration as well as for the Juno team", said Scott Bolton, principal investigator of Juno, from the Southwest Research Institute in San Antonio.