Have you ever seen the northern (or southern) lights? Auroras are part of a natural phenomenon that occurs at far northern and southern latitudes.
According to National Geographic, auroras occur when "charged particles [from the sun] flow along Earth's magnetic field lines. The particles hit the atmosphere at the Poles and excite air molecules, which release the extra energy as light."
There were intense northern lights (aurora borealis) early in 2011, due to the strongest solar activity in four years. Several videos emerged from the early 2011 auroras, and they are quite impressive.