On Saturday, March 29th, the magnetic canopy of sunspot AR2017 erupted, producing a brief but intense X1-class solar flare. A flash of extreme UV radiation sent waves of ionization rippling through Earth's upper atmosphere and disturbed the normal propagation of terrestrial radio transmissions. Radio engineer Stan Nelson of Roswell, NM, was monitoring WWV at 20 MHz when the signal wobbled then disappeared entirely for several minutes:
"The Doppler shift of the WWV signal (the 'wobble' just before the blackout) was nearly 12 Hz, the most I have ever seen," says Nelson.
The flare not only blacked out radio signals, but also produced some radio signals of its own. The explosion above sunspot AR2017 sent shock waves racing through the sun's atmosphere at speeds as high as 4800 km/s (11 million mph). Radio emissions stimulated by those shocks crossed the 93 million mile divide to Earth, causing shortwave radio receivers to roar with static. Here is a plot of the outburst detected by Nelson using a 20.1 MHz RadioJove receiver. Elsewhere, strong bursts were recorded at frequencies as high as 2800 MHz. It was a very broad band event.
NASA's Solar Dynamics Observatory recorded a beautiful movie of the flare:
The flare not only blacked out radio signals, but also produced some radio signals of its own. The explosion above sunspot AR2017 sent shock waves racing through the sun's atmosphere at speeds as high as 4800 km/s (11 million mph). Radio emissions stimulated by those shocks crossed the 93 million mile divide to Earth, causing shortwave radio receivers to roar with static. Here is a plot of the outburst detected by Nelson using a 20.1 MHz RadioJove receiver. Elsewhere, strong bursts were recorded at frequencies as high as 2800 MHz. It was a very broad band event.
NASA's Solar Dynamics Observatory recorded a beautiful movie of the flare:
The flash you just saw was extreme UV radiation, the type of radiation that ionizes the upper layers of our atmosphere. In this case, the ionizing action of the flare led to a rare magnetic crochet, measuring 17 nT at the magnetometer in Boulder, Colorado.
A magnetic crochet is a ripple in Earth's magnetic field caused by electrical currents flowing in air 60 km to 100 km above our heads. Unlike geomagnetic disturbances that arrive with CMEs days after a flare, a magnetic crochet occurs while the flare is in progress. They tend to occur during fast impulsive flares like this one. The magnetic field of sunspot AR2017 is decaying now, but it still poses a threat for eruptions. www.spaceweather.com
A magnetic crochet is a ripple in Earth's magnetic field caused by electrical currents flowing in air 60 km to 100 km above our heads. Unlike geomagnetic disturbances that arrive with CMEs days after a flare, a magnetic crochet occurs while the flare is in progress. They tend to occur during fast impulsive flares like this one. The magnetic field of sunspot AR2017 is decaying now, but it still poses a threat for eruptions. www.spaceweather.com
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