Blowing the Whistle

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Scientists from the University of Alaska uncovered a surprising new twist in the story of lightning.

Researchers Vikas Sonwalkar and Amani Reddy identified a previously unknown type of electromagnetic wave, dubbed a “specularly reflected whistler,” which allows lightning energy to penetrate much deeper into space than previously thought.

Whistlers are a type of electromagnetic wave produced by lightning strikes – named for the whistling sound they make when converted to audio. These waves travel along Earth’s magnetic field lines and scientists have long believed they stay close to the planet’s surface.

But the new study showed that some of this energy bounces off the ionosphere – a charged layer about 55 miles above Earth – and shoots up into the magnetosphere, reaching altitudes of up to 20,000 kilometers. The magnetosphere, a region dominated by Earth’s magnetic field, plays a crucial role in protecting our planet from harmful solar winds.

The scientific duo used data from NASA’s Van Allen Probes, which orbited Earth from 2012 to 2019, as well as earlier studies dating back to the 1960s. The findings suggested that these waves are not a rare phenomenon but occur frequently, and may play a larger role in space weather than previously recognized.

But the paper’s implications are significant because this additional energy can charge and accelerate particles in the magnetosphere. In turn, this produces electromagnetic radiation that can damage satellites and pose health risks to astronauts.

“We as a society are dependent on space technology,” Sonwalkar explained. “Modern communication … and spacecraft with astronauts aboard encounter harmful energetic particles of the radiation belts, which can damage electronics and cause cancer.”

The authors noted that the study opens new avenues for research into how lightning influences space weather.

Jacob Bortnik, a space physicist at UCLA who was not involved in the study, told New Scientist that “lightning was always believed to be a little bit of a smaller player,” but this research opens the door to reevaluating its impact on the magnetosphere.