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September 19, 2013

A flash of lightning produces one of nature’s most impressive sounds. But that’s not the only sound to accompany a blast of lightning. You can also hear it crackling on your A-M radio — often across long distances. And scientists track lightning from far around the globe through odd sounds known as “whistlers.”

Whistlers were first heard on early telephones in the late 1800s, and they were confirmed during World War I.

They’re electromagnetic waves created by lightning. They’re easily detected by radio receivers, which convert the waves to sound.

The waves follow the lines of Earth’s magnetic field. They loop out into space before returning to Earth far away from the spot of the original storm. That makes them good probes for studying Earth’s upper atmosphere, an electrically charged layer atop the atmosphere, and the magnetic environment around our planet.

Whistlers aren’t limited to Earth, though. The twin Voyager spacecraft also detected them at Jupiter, confirming that lightning punctuates the giant planet’s clouds. And the Venus Express spacecraft has detected whistlers on Venus — telling us that stormy skies are common throughout the solar system.

Tomorrow: slowing down a dead star.


Script by Damond Benningfield, Copyright 2013

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