Farside Solar Flares – More to Come?

October 4, 2010
Spaceweather

An active sunspot is about to emerge over the sun's southeastern horizon. It announced itself yesterday with a C4-class flare that hurled material high above the stellar surface, shown here in a movie from NASA's Solar Dynamics Observatory:

Although the explosion happened behind the limb of the sun, it nevertheless yielded enough x-radiation to produce a wave of ionization in Earth's upper atmosphere. Researcher Rob Stammes recorded a sudden ionospheric disturbance (SID) when the wave passed over his lab in Laukvik, Norway. Without even showing itself, the sunspot is already geoeffective.

The source of this activity appears to be old active region 1112. It crossed the Earth-facing side of the sun back in October, a sunspot dragging a magnificent filament of magnetism behind it. Two weeks later, AR1112 t is coming around for a second pass. Yesterday's eruption may be read as "hello, I'm back."