Sunspot AR3664 just did it again.

Spaceweather.com from NOAA

GEOMAGNETIC STORM WATCH (G2): NOAA forecasters say that G2-class geomagnetic storms are possible on June 10th when a CME launched by yesterday’s M9.7 flare is expected to hit Earth. The CME is bright and massive; a direct hit would probably cause a severe geomagnetic storm. However, this will be just a glancing blow, so only moderate storming is likely. Aurora alerts: SMS Tex t

SOLAR FLARE AND HARD RADIATION STORM: Sunspot AR3664 just did it again. The record-setting active region produced another very strong solar flare on June 8th (0149 UT), hurling a massive plume of plasma into space:

This was an category M9.7 event, only percentage points from X-class. Radiation from the flare ionized the top of Earth’s atmosphere, causing a deep shortwave radio blackout across the western Pacific Ocean: map.

The sunspot is currently located in a region of the sun that is magnetically well-connected to Earth. As a result, protons accelerated by the explosion are spiraling toward us, peppering the top of Earth’s atmosphere as well as all spacecraft near our planet. Here’s an example of the effect this can have:

Every speck of ‘snow’ in this SOHO coronagraph movie is caused by an energetic proton striking the spacecraft’s camera. Through the fog you can see a bright CME emerging from the blast site. It will sideswipe Earth on June 10th.

At the moment the radiation storm is category S1 (Minor), several levels below the peak of the scale. It does not pose a biological threat to astronauts or air travelers.

Nevertheless, this storm is interesting because it contains an unusually high fraction of “hard” protons with high energies > 100 MeV. Hard protons are good at charging spacecraft bodies, fogging their cameras, and causing reboots of onboard computers. It would not be a surprise to hear reports of minor satellite problems in the days ahead. Solar flare alerts: SMS Tex t

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