"A solar flare that occurred around 2 a.m. Thursday morning may create a spectacular display of northern lights Saturday evening. The midlevel flare had a long duration and was directed at Earth. Solar flares create auroras when radiation from the sun reaches Earth and interacts with charged protons in our atmosphere. The effects are greater at the magnetic poles and weaken as they move south from the Arctic or north of the Antarctic. In the northern hemisphere the results are called the aurora borealis, with the aurora australis being its southern counterpart. The result is a spectacular display of light and color for areas with clear enough views."
Via Seth Dixon