The Northern Lights or aurora borealis are a natural phenomenon that can paint the night sky with unearthly, surreal color. The Southern Lights or aurora australis also occur but are not as often observed.
The aurorae are caused by charged particles ejected from the sun. When these particles reach the earth, they collide with gas atoms and molecules in the earth's upper atmosphere, energising them and creating a spectacular multi-coloured light show. Charged particles are affected by magnetic fields, so the Lights occur mainly at far northern or southern latitudes near the Earth's magnetic poles.
The Lights look somewhat similar to a sunset in the sky at night, but appear occasionally in arcs or spirals usually following the earth's magnetic field. They fairly often look like moving curtains of light, high in the sky. They are most often light green in color but often have a hint of pink. Strong eruptions also have violet and white colors. Red northern lights are rare, but are sometimes observed.