How an Aurora Forms

Auroras occur when energetic charged particles associated with the solar wind and Earth’s magnetosphere are accelerated along magnetic fields and collide with gases in the upper atmosphere. Excited atoms and molecules emit light: oxygen most often produces green and red hues, while nitrogen can produce blue, purple, and pink. Auroras usually cluster around polar ovals, but during strong geomagnetic storms those ovals expand and auroras can be seen at lower latitudes.