The dark side of the sun
There were no fireworks on the sun to welcome in the new year, and only a few C-class flares during the last day of 2014. Instead, the sun starts 2015 with an enormous coronal hole near the south pole. Coronal holes are regions of the corona where the magnetic field reaches out into space rather than looping back down onto the surface. Particles moving along those magnetic fields can leave the sun rather than being trapped near the surface. Those trapped particles can heat up and glow. In the parts of the corona where the particles leave the sun, the glow is much dimmer and the coronal hole looks dark.
