Northern Lights Or Auroras Borealis

Auroras Borealis or more commonly know as Northern Lights are beautiful to watch; how these light displays come into existence is equally fascinating.

On clear cold Canadian nights one can stand outside and see unusual colors dancing in the dark sky. Centuries ago, in Canadian Inuit and Native folklore, this would have signified a time to make "spirit journeys" to save one's soul from death. Or it could have meant a time to take advantage of the miraculous healing powers that these moving lights were said to possess. Today few believe in the magical power of these Northern Lights, but most people still remain awed by their beauty.

To call these cavorting colors Northern Lights is not an accurate description. In actual fact this kaleidoscope of colors can appear both in the northern and southern hemispheres, usually in an irregularly shaped oval above the magnetic poles. Light displays in the south are called aurora australis and displays in the north are called aurora borealis.

Shades of these auroras can vary depending on the oxygen and nitrogen levels in the air. The most common color is a brilliant yellow-green, and the rarest is a completely red light. Other shades that have been seen include blue and violet. In most cases these lights show in the form of patches and scattered clouds. Shooting rays, streamers and rippling curtains have also been reported.

Throughout the years scientists have researched and tried to discover what causes these beautiful displays. Researchers have known since the 1600s that the earth possesses a magnetic field. However, it was not until the 1950s, after extensive research that physicists connected the magnetism of the earth to the display of colorful auroras.

This discovery can be attributed to a scientific team from the University of Iowa. By launching a rocket into the aurora, these scientists were able to observe auroral electrons. From their observations they concluded that Northern Lights are partially caused by the electronic activity of the sun. In the most simplistic terms, these auroras are caused by collisions between gaseous particles in the earth's atmosphere and particles released from the sun's atmosphere. The sun's particles scuh as electrons and protons are thrown into the earth's atmosphere by the solar wind. When these electrons and protons make contact with the gases in earth's atmosphere, the energy created appears as colored lights.

As mentioned before, this light varies due to the amount of oxygen and nitrogen gas in the earth's atmosphere. The yellowish-green colour is caused by oxygen at lower altitudes of around 60 miles above the earth's surface. (This is a distance ten times higher than a jet aircraft flies.) The rare all-red colour auroras are produced by high altitude oxygen. High altitude refers to the levels of oxygen settling at a maximum distance of 200 miles from the surface of the earth. Positive or negative charged (ionized) nitrogen molecules cause the dull bluish or purplish-red colors sometimes seen around the borders of the aurora.

To further explain and simplify the occurrence of auroras, some scientists in Norway have compared this phenomenon with the light that can be seen on a television. In order to view images on a television, "a beam of electrons controlled by electric and magnetic fields strikes the screen". The resulting glow depends on the phosphor (type of chemical) that coats the television monitor. Similar to the image on television, Northern Lights are created from "the air glowing as charged [particles] rain down along the Earth's magnetic field lines".

In 1967 scientists discovered that northern and southern auroras come from the same magnetic source. This means that if there is a great deal of aurora activity in the northern regions then it is probable that there will be a mirror aurora in the southern hemispheres. Although Northern Lights happen in both the northern and southern hemispheres, the best places to view these auroras are in the colder northern countries and provinces. Nunavut, the Yukon, Alaska and the Northwest Territories have been cited as excellent locations to see auroral activity. Clear aurora displays have also been reported in Norway, Greenland and Iceland. Even though southern auroras (or aurora australis) are rarely seen and reported, researchers have discovered these dancing lights in New Orleans and the Antarctica.

Scientists have discovered that auroral activity is cyclic. This means that Northern Lights operate on a certain timeline depending of various factors in the earth's atmosphere. It has been determined that the aurora borealis and aurora australis peak every eleven years. According to "The Aurora Watcher's Handbook", every decade or two there is a large auroral event that is witnessed by people in both the southern and the northern hemispheres. The section of this book called "Great Magnetic Storms" states that the last time this happened was in the March of 1989. Depending on the scientist, the next peak period is either in 2001 or 2002.

The ideal places for optimum aurora viewing are areas where there is little "light pollution" (daylight, light from cities, cars and homes). Long periods of darkness and clear nights also aid in watching Northern Lights. For these reasons the majority of research facilities for the study of auroras are located in the north, near remote communities. For these reasons the most spectacular auroral displays are seen in the North.

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