SOLAR STATIC: Active sunspot 1302 has turned the sun into a shortwave radio transmitter. Shock waves rippling from the sunspot’s exploding magnetic canopy are exciting plasma oscillations in the sun’s atmosphere. The result: Bursts of static are issuing from the loudspeakers of shortwave radios on Earth. Amateur radio astronomer Thomas Ashcraft recorded this sample from his backyard observatory in New Mexico on Sept. 24th:

Dynamic spectrum: The horizontal axis is time (h:m:s), the vertical axis is frequency (MHz). Image credit: Wes Greenman

“Saturday was a super-strong solar day with near continuous flaring and radio sweeps,” says Ashcraft. “The sound file (above) corresponds to an M3 flare at 1918 UTC. It was the strongest radio sweep of the observing day.”

“Try listening to the radio bursts in stereo,” he advises. “I was recording on two separate radios at 21.1 MHz and 21.9 MHz, and I put each one into its own channel of the audio file. This gives a spatial dimension as the bursts sweep down in frequency.”

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