A display of light in the night sky of the Northern hemisphere. It is caused by charged particles from the sun. When large numbers of these particles break through the magnetic field of Earth, they collide with atoms in our atmosphere and create light in certain colors. Think of a rainbow. The sunlight hits countless raindrops producing a colorful rainbow.
The name Aurora Borealis comes from the words Aurora (the Roman goddess of dawn) and boreal (the Greek name for north wind). Auroras (or more correctly aurorae) in the Southern hemisphere are called Aurora australis.