In addition to sending out heat and light, the sun also emits a constant stream of charged particles, known as the solar wind. These particles are largely deflected away by the earth's magnetic field, except near the poles, where the lines of the magnetic force form a funnel, leading these particles down towards the upper atmosphere. When these particles encounter molecules such as nitrogen and oxygen gas in the upper atmosphere, some of their energy is transferred, leading to excited state forms of these atmospheric gases. When the excited state forms relax back down to the ground state, that excess energy is given off in the form of light. The result is the light show known as the aurora borealis in the north and the aurora australis in the south. Dave and John from briXwerX made this great northern lights scene. Be sure to watch the video to see the light flickering. BTW, they also dedicated this as a tribute to Heather Braaten and her children.