This remarkable feature of the natural world is known as an aurora, and it comprises electrically charged particles colliding with each other as they enter the atmosphere of the Earth. These collisions produce shafts of color that may be seen from the ground. They are visible above the magnetic poles of the southern and northern hemispheres; the lights above the northern hemisphere are called the Aurora Borealis, as opposed to the Aurora Australis, which can be viewed from the southern hemisphere.
You might see the lights in a variety of hues, including pink, green, violet, blue, red, and yellow. They also appear in a range of shapes – from patches of light, to colored arcs, rays, and streams, to cloudy formations, to curtains of light that look as though they are rippling with color.