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Posted: Dec 04, 2012
Cosmic radio waves mimic chirping of 'alien birds'
(Nanowerk News) NASA's Van Allen Probes have been exploring the hostile radiation belts surrounding Earth for just three months. But already, they've collected detailed measurements of high-energy particles and radio waves.
Scientists say these waves can provide an energy boost to radiation belt particles, somewhat like ocean waves can propel a surfer on Earth. What's more, these so-called chorus waves operate in the same frequency as human hearing so they can be heard.
A University of Iowa physicist played a recording of these high-pitched radio waves at a conference Tuesday in San Francisco. Craig Kletzing says it sounds like the chirping of "alien birds" and crickets.
The Waves tri-axial search coil magnetometer and receiver of EMFISIS captured several notable peak radio wave events in the magnetosphere that surrounds the Earth. The radio waves, which are at frequencies that are audible to the human ear, are emitted by the energetic particles in the Earth’s magnetosphere.
“People have known about chorus for decades,” says EMFISIS principal investigator Craig Kletzing, of the University of Iowa. “Radio receivers are used to pick it up, and it sounds a lot like birds chirping. It was often more easily picked up in the mornings, which along with the chirping sound is why it’s sometimes referred to as ‘dawn chorus.’”