The first few months of 2014 have certainly been active for our nearest star and last night the sun unleashed another X-class flare — the most powerful type of solar flare.
The sun erupted on Thursday at 8:27 p.m. EDT, and although the active region that generated the intense radiation was located on the sun’s limb, facing away from us, the electromagnetic radiation generated was felt here on Earth.
In space, X-class flares can cause significant damage, particularly if you happen to be an unprotected astronaut on a spacewalk, but down here on Earth, the health impacts are not a problem. Our thick atmosphere absorbs the energy of X-ray and extreme ultraviolet wavelengths. But the uppermost atmospheric layer, called the ionosphere, becomes extremely ionized and can affect radio wave propagation around the globe, sometimes meddling with signals from GPS satellites and aircraft.
According to NASA’s Tony Phillips at Spaceweather.com, last night’s X1.3 flare caused a high-frequency radio wave blackout on the sun-facing side of the Earth shortly after the eruption.
Solar flares are spawned by highly-stressed magnetic fieldlines protruding through the sun’s photosphere (colloquially known as the sun’s “surface”), usually above active regions. Often sunspots are associated with these regions and are linked with the sun’s activity and therefore flares and coronal mass ejections.
Flares are triggered when huge loops of magnetism (often observed as bright coronal loops) are forced together. If the conditions are right, magnetic reconnection can occur, causing rapid acceleration of solar plasma (the hot, ionized gas that originates from the sun’s interior), generating intense radiation that can be observed as a flare.
The sun is currently experiencing its most active period in the 11 year solar cycle known as “solar maximum.” It is believed that the cycle peaked in 2013, but as last night’s flare proves, the sun hasn’t quite finished erupting yet.