Question: what causes the northen lights

Adam Tuff answered on 16 Mar 2011:

The Northern lights are caused by particles that are streaming off the sun. these particles usually have charge to them, and interact with the earth’s magnetic field, and they start circling the field lines that point towards the magnetic poles of the Earth – when they follow them down through the atmosphere, they react with the gases there and cause light to be emitted – sometimes in really vivid greens! You can often see it when flying in a plane going to America or the far east!