![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Polarlicht_2.jpg/340px-Polarlicht_2.jpg)
Photo credit: Senior Airman Joshua Strang, United States Air Force
An aurora, caused by the release of energy as charged particles collide with atoms in the Earth's upper atmosphere.
Photo credit: Senior Airman Joshua Strang, United States Air Force
An aurora, caused by the release of energy as charged particles collide with atoms in the Earth's upper atmosphere.