STRONGEST SOLAR FLARE OF THE CURRENT CYCLE - RADIO BLACKOUTS OVER ALL OF CONUS
Sunspot AR3664 just unleashed the strongest solar flare of the current solar cycle–an X8.7-category blast from beyond the sun's western limb. X marks the spot in this image of the flare from NASA's Solar Dynamics Observatory
Because the sunspot is behind the edge of the solar disk, the flare was partially eclipsed. It was probably even stronger than it appeared. "X8.7" is almost certainly an underestimate of the flare's true strength.
Extreme ultraviolet radiation from the flare ionized the top of Earth's atmosphere, causing a deep shortwave radio blackout over the Americas. Ham radio operators, aviators and mariners may have noticed a sudden loss of signal at all frequencies below 30 MHz.
Subatomic debris from this event might soon reach Earth, guided toward our planet by the Parker Spiral (read the story below for more information). Also, a CME might be in the offing. Stay tuned for updates!
Giant sunspot AR3664 is no longer facing Earth. That makes it extra dangerous. The Carrington-class sunspot is passing over the sun's western limb–a region of the sun that is magnetically connected to our planet. Indeed, we are feeling the effects of that connection right now; take a look at this map of ongoing radio blackouts
Red zones in the map show where shortwave radio signals are being absorbed. Inside the Arctic Circle, frequencies below 30 MHz are almost completely blacked out, a nuisance for polar aviators and ham radio operators.
What's causing this? Protons accelerated by solar flares in the magnetic canopy of AR3664 are following the Parker Spiral back to Earth. Think of it as a magnetic superhighway. The arriving particles are funneled by our planet's magnetic field toward the poles where they ionize the atmosphere and interfere with the normal transmission of shortwave radio.
This polar cap absorption event could last for days, especially if it is boosted by more flares from AR3664. You can can monitor its progress here.