Scientists Solve a 45-Year-Old Mystery of Lightning on Saturn. New analysis of Voyager data provides long-awaited answers
10. 04. 2026
A team of scientists from the Institute of Atmospheric Physics of the Czech Academy of Sciences, led by Masafumi Imai, has successfully unraveled a mystery surrounding lightning on Saturn from the historic Voyager missions. Data from the spacecraft, which flew past Saturn in the 1980s, had long baffled researchers: the instruments reported that lightning in the planet's atmosphere was "broadcasting" signals from a completely different location than physics would dictate. Research by our scientists, published in the journal JGR: Planets, now explains this confusing phenomenon and precisely locates the detected lightning signals with their associated thunderclouds within the atmosphere of Saturn.
Radio emissions from lightning on Saturn (known as Saturn Electrostatic Discharges, or SEDs) were discovered by the Voyager spacecraft in the 1980s. However, their interpretation remained incomplete until now. "New insights from the Cassini mission, which explored Saturn between 2004 and 2017, showed us that the polarization of the electromagnetic signals emitted by these discharges is directly linked to the hemisphere where the storm originates," explains Masafumi Imai from the Institute of Atmospheric Physics. This led the scientists to re-analyze the 45-year-old Voyager data using modern methods.
The Mystery of the Equator vs. the 35-degree North latitude
Original studies from the 1980s suggested that the lightning originated in the equatorial region of Saturn because the periodicity of the discharges in the Voyager recordings matched the rotation of the atmosphere at the equator. However, Voyager’s cameras detected no storm clouds in that area.
The new analysis has resolved this discrepancy. It confirmed that the lightning sources were actually located at 35° North latitude, where contemporary images did indeed show convective storms. "The seemingly faster periodicity matching the equator was caused by the so-called 'over-the-horizon effect' in the ionosphere of Saturn, which bends radio waves," says Masafumi Imai. This phenomenon was unknown during the Voyager era and was only confirmed much later by the Cassini mission.
Correcting the Errors of Legacy Instruments
One of the greatest challenges was the confusing polarization of signals in the original data. The radio receivers on the Voyager probes had to operate under strict data transmission limits, leading to simplified onboard analysis that struggled with the extremely short pulses emitted by lightning.
The team from the Institute of Atmospheric Physics, in collaboration with colleagues from the University of Graz led by expert on lightning at Saturn Dr. Georg Fischer, developed a new calibration method. This method accounted for the orientation of the spacecraft's antennas relative to the electromagnetic wave source. Through numerical simulations, the team proved that when the waves hit the antennas at the correct angle, they do indeed exhibit the expected polarization corresponding to the northern hemisphere.
Why Study Old Data?
According to the scientists, studying historical archives is vital for understanding long-term processes. "Lightning on Saturn is still full of mysteries. It is believed that lightning activity is influenced by the planet’s seasons, which last nearly 30 Earth years," says Masafumi Imai. "Data from a single mission is not enough to capture these cycles. As long as old records exist, it is worthwhile to revisit them with modern ideas and technologies."
Media Contact:
Masafumi Imai, Ph.D.
+420 267 103 059
imai@ufa.cas.cz
Ing. Ivana Kolmašová, Ph.D.
+ 420 603 423 083
iko@ufa.cas.cz
Reference:
Imai, M., Fischer, G., Taubenschuss, U., Kolmašová, I., Santolík, O., & Píša, D. (2026). Polarization measurements and source locations of Saturn electrostatic discharges during the Voyager era. Journal of Geophysical Research: Planets, 131, e2025JE009079. https://doi.org/10.1029/2025JE009079
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