Et Call
Extraterrestrial chorus heard
The Van Allenprobes recently recorded “chorus†waves, electromagnetic disturbances that ripple through the belts.
Is it alien birds singing alongside crickets? Or the sound of radio waves sweeping through Earth's magnetosphere? A recently released recording is a little bit of both. The soundtrack captures “chorus†waves, electromagnetic disturbances that ripple through belts of charged particles that surround Earth. The chorus becomes audible to the human ear when translated into sound waves, as heard in a recording made by space physicists at the University of Iowa. Ham radio operators have known about this chorus for decades, but scientists now have a lot more data on it thanks to a pair of satellites known as the Van Allen probes. NASA launched them in August to fly through and study Earth's two main radiation belts, called the Van Allen belts an inner one made mostly of protons and an outer one made mostly of electrons. The electronics on most spacecraft get fried if they spend too much time in these belts, but the Van Allen probes are built with components that won't fritz out when charged particles hit them. Already scientists are uncovering surprises from the mission, some of which they reported December 4 at a meeting of the American Geophysical Union. The radiation belts turn out to be much more active than anyone had suspected, having shifted their location and intensity each time the probes swept through on their nine-hour orbits.
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