Northern Lights or Aurora Borealis, haunted skies over the island of Kvaløya, near Tromsø Norway on December 13, 2009. This 30 second long exposure records their shimmering glow gently lighting the wintery coastal scene. A study in contrasts, it also captures the sudden flash of a fireball meteor from December's excellent Geminid meteor shower. Streaking past familiar stars in the handle of the Big Dipper, the trail points back toward the constellation Gemini, off the top of the view. Both aurora and meteors occur in Earth's upper atmosphere at altitudes of 100 kilometers or so, but aurora are caused by energetic charged particles from the magnetosphere, while meteors are trails of cosmic dust.
Image Credit & Copyright: Bjørnar G. Hansen
Explanation from: http://apod.nasa.gov/apod/ap091219.html