Magnetic Northern Lights Attract Unusual Interest
November 11, 2001

The shimmering kaleidoscopic Aurora Borealis or northern lights have intrigued observers for centuries. Scientific study of the auroras began in 1719, but modern scientists are still searching for answers to many questions concerning the phenomenon. An aurora continues to be a challenging enigma.

In recent years, these mysterious ribbons of color have been under attack by rockets bearing special scientific instruments in their nose-cones, scrutinized by artificial satellites, photographed extensively, and visual observers have been organized into a worldwide network. Even the casual knowledge, however, can add to the excitement of viewing the unearthly beauty of the auroras.

Auroral activity probably occurs constantly in the polar regions. It is only when there are unusually great magnetic disturbances that viewers at our latitude have an opportunity to observe them. The occasions usually occur in early spring and fall.

Two types of auroral luminosity are recognized in classifying them: ribbons and cloud- like patches. The ribbon forms my reach vertical heights of over 1000 miles, but appears to be only a few hundred yards in thickness. They usually form tiers, like stage curtains, one behind the other. Aurora specialists have the following descriptions for the various types of ribbon forms: when at its most quiet the luminosity appears as an arc, fairly steady, with the greatest brightness at the bottom. As the ribbon becomes more active, it develops fine folds which look like columns or rays of light. Further activity results in deeper folds, superimposed upon one another, and these are designated as "rayed bands". Often this phase has a pink glow at the bottom. A final burst of action causes tremendous folds, followed by subsidence and a return to the original arc. Sometimes, after an intensively active period, the ribbons collapse into the cloud-like patches, most commonly after midnight.

The earth is a gigantic magnet. The auroras, according to present understandings, are the result of an interaction between the magnetic fields that surround the earth and a high-velocity "wind" of particles streaming from the sun. The "wind" apparently is the result of great solar flares that spin off into space like pinwheels, causing a disturbance in the earth's magnetic field, which acts as a "cushion" deflecting or absorbing most of the bombarding particles. The particles of electrified solar hydrogen which manage to penetrate the earth's atmosphere near the poles, bombard the atoms and molecules of nitrogen and oxygen gases, causing them to become luminous to produce the aurora. The characteristic wave lengths of these radiations give clues
as to the kinds of atoms and molecules in the upper atmosphere. Excited oxygen atoms cause both red and green light. Ionized nitrogen atoms give off violet and blue light. A weak source of red light is caused by excited hydrogen atoms.

No two auroras are alike. The southern lights or aurora Australis, however, occur at the same time with the same intensity as their northern counterpart.