For the first time, researchers have simulated the formation of lightning on an exoplanet
Lightning is well known on Earth and also occurs in other parts of our solar system. But could there also be lightning on planets that orbit entirely different stars?
Researchers from TU Dortmund University and their partners have come one step closer to answering this question. For the first time, they have used computer models to simulate how the initial stages of lightning might develop in the atmosphere of an exoplanet.
Using data from the James Webb Space Telescope, they studied K2-18b, an exoplanet located about 124 light-years from Earth. An exoplanet is a planet that orbits a star other than the Sun.
“Of course, we can’t see lightning on a planet 124 light-years away. But observations from the James Webb Telescope provide us with information about the atmosphere and allow us to simulate whether the physical processes that lead to lightning can occur. Our results show that this process can indeed take place in the atmospheres we studied,” says Elloise Fangel-Lloyd. She is a researcher at the Danish Meteorological Institute (DMI) and conducted the work as a doctoral student at the Technical University of Denmark (DTU).
She is the first author of an article presenting the results, which has just been published in the journal Scientific Reports (part of the Nature group).
Small electrical discharges could be the beginning of lightning
The researchers simulated what are known as streamers.
These are small electrical discharges that typically occur during the early stages of lightning formation. In other words, the researchers did not simulate a complete lightning strike, but rather the process that can trigger its formation.
The simulations show that the discharges capable of triggering a lightning strike can occur in all three possible compositions of the exoplanet’s atmosphere examined by the researchers.
Lightning could form more easily there than on Earth
The calculations also show that only about half the electric field strength required on Earth is needed for electrical breakdown in the modeled atmospheres.
The results therefore suggest that the atmosphere of K2-18b may be more conducive to lightning formation than Earth’s atmosphere. “An electric field exerts a force on electrically charged particles. If the field becomes strong enough, the gas in the atmosphere can be ionized; this enables the formation of electrical discharges that can lead to lightning,” says Christoph Köhn, a senior researcher at the Department of Physics at TU Dortmund University and the Department of Astrophysics and Atmospheric Physics at DTU, and co-author of the study.
“What’s particularly interesting here is that we can use our knowledge of electrical discharges on Earth to investigate which processes might be taking place in the atmosphere of a planet many light-years away.”
The researchers’ simulations also show that the water vapor content of an atmosphere influences how easily the process leading to lightning can be triggered.
Once a lightning strike has formed, it can alter the chemistry of an atmosphere and thus have implications for potential life and habitability—both on a planet like K2-18b and on other exoplanets.
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