The Polar Auroras Explained

"The dance of the spirits" are one of many ancient names for the astronomical phenomena we call the northern and southern lights. The old Nordic culture said the lights were reflected light from oceans of fire. The Swedish used to think they were huge schools of herring with sunlight shining off of their scales. Other northern indigenous peoples believed that the auroras were places of the dead. Universally the older beliefs and superstitions about the lights in the sky were one of awe and respect.

Today, modern science has put the once hallowed apparitions into a more logical, albeit still awe inspiring, perspective. The polar auroras, or in their Latin names, aurora borealis in the northern hemisphere and aurora australis in the southern hemisphere, are brilliant spectacles of particles of energy and matter that combine into multicolored curtains of light high in the night sky.

Like a Roman candle being lit on the Fourth of July, the spectacular colors of the fireworks are hidden until a source of energy is applied. The flame that lights the fuse is the energy waves and particles from the Sun, and the multicolored fireballs that shoot out are the molecules of the atmosphere reacting to that energetic reaction.

The magnetosphere of the Earth emanates from the north and south poles, and located directly above them are magnetic sinkholes where solar winds and radiation seep into the ionosphere layer of our atmosphere. The solar winds are a continuous flow of subatomic particles from the Sun's atmosphere that pass throughout our entire solar system. As the energy from the Sun comes in contact with the magnetosphere, the energized solar particles, mainly electrons and protons, follow the magnetic lines and get drawn to the poles.

These particles collide with existing oxygen and nitrogen atoms high in the atmosphere and ionize or excite the molecules. The resulting colors of reds, blues, violets and greens are the visible energy given off by the energized particles as they shed off the extra energy from the solar winds and return to a grounded state. The variation in the colors is derived from the type of element that was energized and just how much energy it had taken in.

The distinct bands or curtains of color from an aurora are tied to how the atmosphere is layered. With more oxygen at higher altitudes, the top of an aurora is generally red or brownish-red. As the energized particles fall through the layers, they come into contact with nitrogen molecules and the colors given off can be blues and greens. At the lowest levels of the atmosphere, colors can combine and turn the auroras into pinks and purples.

When the Sun gives off particularly strong plasma bursts or sun spots are occurring, the colors from the auroras are much more intense and frequently can be seen at a much greater distance from their regularly viewed regions closer to the poles. There have been verified reports of the northern lights being viewed as far south as Florida in years past.

Not only are the auroras visible from the ground, but they extend upward into space as well. Photographs from orbiting satellites and spacecraft visibly show how the magnetic field of the Earth protects us on the ground and how many hundreds of miles the invisible shield extends from the surface.

With ancient beliefs and superstitions about the mysterious polar auroras behind us, today's people can view the curtains of shining and billowing lights for the natural spectacle of energy and matter that they are.