Big sunspot AR2738 is crackling with B-class solar flares.

B IS FOR “BOMB”: Big sunspot AR2738 is crackling with B-class solar flares. This morning in France, astrophotographer Philippe Tosi caught the sunspot in mid-flare, inserting an image of Earth for scale.

On the “Richter Scale of Solar Flares,” B-class events are considered weak. In solar physics, however, such terms are relative. A typical B-class solar flare releases as much energy as 100 million WWII atomic bombs. Only on the sun, which is itself a 10^27 ton self-contained nuclear explosion, would such a blast be considered “weak.”

Despite the objective potency of B-flares, they have little effect on Earth. Their UV output causes short-lived waves of ionization to ripple through our planet’s upper atmosphere, subtly affecting the propagation of shortwave radio waves. That’s it. An M-class or X-class flare would have more impact, but the relatively simple magnetic field of sunspot AR2738 does not appear to harbor sufficient energy for those more powerful explosions.