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NOAA - 04/23/2023


The explosion that hurled a CME toward Earth on April 21st also illuminated our planet with an intense burst of shortwave radio static. Amateur astronomer Thomas Ashcraft of New Mexico recorded the outburst:

"Few solar radio bursts show as hot purple on my spectrograph, but this one 'rang the bell'," he says. "Here is an audio recording in stereo with 22 MHz in one channel and 19 MHz in the other."

The static in Ashcraft's recording, which washes over the listener like a slow ocean wave, is naturally produced. Astronomers classify it as a Type V solar radio burst caused by energetic beams of electrons ray-gunning through the sun's atmosphere. The electrons were accelerated by the same underlying explosion that hurled a CME toward Earth.

Solar radio bursts are an underappreciated form of space weather. We often talk about radio blackouts, which happen when solar flares ionize the top of Earth's atmosphere. Radio blackouts suppress the normal propagation of terrestrial radio signals. Solar radio bursts, on the other hand, produce a radio drownout. Intense static from the sun overwhelms normal transmissions, drowning out the voices radio operators are trying to hear.

Solar radio bursts will happen more and more often as Solar Cycle 25 intensifies. You can hear them yourself using a RadioJOVE radio telescope kit from NASA.

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