Auroral light is similar to light from color television. Auroral light is the from the air glowing as charged particles, particularly electrons, rain down along the Earth's magnetic field lines. The color of the aurora depends on the type of atom or molecule struck by the charged particles. Oxygen at lower altitudes, about 60 miles up, produces a brilliant yellow-green, the brightest and most common auroral color. The nitrogens create the purplish-red lower borders and ripple edges of the aurora.
Auroral displays vary from night to night and during a single night.
As an arc moves toward the equator, new ones may form on its poleward side. Appearing within arcs are upward-reaching striations aligned with the magnetic field, giving the impression of curtains of light. Ripples and curls dance along the arc curtains and pulsating patches of light may appear in the morning hours. If you have never seen the aurora yourself, videos are available that will give you some idea of what it is like, but you will have to come to Alaska in the wintertime to really appreciate the beauty of the aurora.