Lightnings on Jupiter Pulse Like Discharges on Earth

Based on new data from the Juno probe, the team concludes that lightning bolts on Jupiter evolve similarly to Earth's intra-cloud lightning. "Lightning research has been done by older probes, but it was only Juno that travelled to the planet in 2016 and was able to obtain detailed and well-distinguished data," says Ivana Kolmašová of the Institute of Atmospheric Physics of CAS and Matfyz.

The Analysis of Half a Million Records

The more precise knowledge of lightnings on Jupiter required a time-consuming analysis of nearly half a million records collected during the first five years of Juno's mission. As a result, five hundred groups of pulses numbering three to twenty-five isolated pulses were found. This was followed by the determination of the time lags between each pulse, with the most common occurrence being a delay of one thousandth of a second.

"The next course of action was fairly straightforward," explains the scientist. Assuming that, as on Earth, an emerging discharge spreads in a jump at the same rate of hundreds to thousands of kilometres per second in the lightning channels inside Jupiter's water storm clouds, a combination of this velocity and the length of delay between pulses suggests that lightning channels on Jupiter lengthen in leaps of hundreds of meters to units of kilometres.

"Similarly, discharges of preceding Earth lightning are spreading inside the cloud, as confirmed by records from measurement stations operated by the Institute of Atmospheric Physics of CAS of the Czech Republic at the Milešovka and Dlouhá Louka observatories in North Bohemia. We have used these in this study as evidence of the similarity of the time scales of preparatory atmospheric discharges on both planets," adds Ondřej Santolík of the Institute of Atmospheric Physics of CAS and Matfyz.

Juno: Jupiter within Reach

The core part of the Juno mission lasted from July 2016 to June 2021. The probe was then approaching very close to Jupiter, the Solar System's largest planet, every 53 days.

Electromagnetic receivers measuring onboard the probe in various frequency bands have contributed greatly to understanding the phenomena associated with lightning and thunderstorms. For example, they have revealed that lightning occurs most often in the central and polar latitudes, and unlike Earth, there are almost no lightning near the equator.

It has also been shown that electromagnetic signals produced by lightning bolts, so-called rapid whistles, are transmitted to the Juno probe by very thin plasma. It means that there are dense holes in Jupiter's ionosphere that eluded scientists due to earlier, less accurate measurements. Surprisingly, the statistics of recorded whistles showed that the frequency of lightning on Jupiter was close to that of terrestrial lightning. Through the probe's transits, we also know that there appear to be sprite lightning on Jupiter, similar to Earth observations that we know.

Publication

I. Kolmašová, O. Santolík, M. Imai, W. S. Kurth, G. B. Hospodarsky, J. E. P. Connerney, S. J. Bolton, R. Lán. Lightning at Jupiter pulsates with a similar rhythm as in-cloud lightning at Earth. Nature communications. 2023, https://www.nature.com/articles/s41467-023-38351-6