The Northern Lights

The Aurora Borealis are naturally colored lights that appear at night typically in the polar zones. They usually occur in the ionosphere which is the upper most part of earth's atmosphere because it is ionized by solar radiation. The first name was derived from the Greek goddess of dawn Aurora and the second name is the Greek translation for north wind (Boreas). The Aurora Borealis is only visible in the Northern Hemisphere typically from March to April and September through October. The Cree people indigenous to Alaska and Antarctica call this phenomenon the dance of the spirits because they believe it has to do with spirituality and religious worship to their god.

Scientific Cause

The source behind this effect is simply solar wind flowing past earth. Earth's magnetosphere and solar wind consists of plasma (ionized gas) which conducts electricity. When an electrical conductor is placed within a magnetic field while relative motion occurs in a direction that a conductor cuts across, rather then along the lines of the magnetic field, an electrical current is induced into the conductor and electrons flow within it creating a dynamo effect. The magnetosphere and solar wind are typically two electrical conducting sources that are able to generate electric currents when they come into contact with each other, thus extracting energy from the solar wind as well. The earth is constantly immersed in the solar wind and hot flow of plasma gas emitted by the sun in all directions, a result of a million-degree heat of the sun's outer most layer, the solar corona. The magnetosphere of the earth extends past 70,000 km. An extremely bright light effect is the result of a Birkeland current which is a specific magnetic field aligned with earth's magnetosphere and flows toward earth on the dawn side and in the opposite direction on the dusk side. Inretrospect the solar wind and electrical conductors repel, continue at a rapid pace around earth while the magnetosphere is the center for all electrical activity.

Aurora Borealis: Blue Marble Image effect from solar winds and

electrical energy in the magnetosphere

Structure of Earth's Magnetosphere

Frequency of Northern Lights

The Northern lights is most common in the poles. They are occasionally seen in temperate latitudes that is when a strong magnetic storm of electrically charged electrons and protons expands to create an auroral oval image. During an eleven-year period when these magnetic storms are at their highest frequency, the light effect is at its strongest and brightest. These storms ignite the Aurora Borealis during the months equinox's in other words these magnetic storms are dependent upon earths seasons. During the autumn and spring months, the interplanetary magnetic field and the earth link up as the earths direction switches north. The solar wind enables the earth and the sun to move closer to each other which partially accounts for this semi-annual event to take place. The Aurora typically diffuses a glow or curtain as referred to in an east to west direction. Each curtain or ray consists of many parallel magnetic fields spiraling around earth. Scientists have not yet identified exactly why and how the event occurs but they do know for certain that the earth's magnetosphere and an electrical storm need to coincide with each other in order for the lights to be visible.

History and Meaning

The discovery of the northern lights dates back to 1771 when Benjamin Franklin first brought local attention to these strange lights. He emphasized that shifting lights to a concentration of electrical charges in polar regions intensified by snow and other moisture were the underlying cause. Since that theory in 1900 Kristian Birkeland determined that these auroral electrons are emitted by the suns beams after experimenting with a vacuum chamber, electron beams and magnetized spheres that showed how electrons were guided to the polar regions. The most recent study performed in 1962 concluded that the aurora was produced by solar wind guided by earths field lines at the top of the atmosphere. Many different cultures have had their own interpretation of these northern lights believing that they are some how tied to culture and religion. The Scandinavian people call the lights herring flash believing that the lights are cast by large swarms of herrings over the sky. Russian folklore believes that the lights symbolize a fire dragon. The Algonquin people believe that the lights represent a higher power and that their ancestors will dance around a ceremonial fire.

Aurora Borealis Bare Lake, Alaska

Red and Green Aurora Fairbanks, Alaska

Green Aurora, Greenland

The Northern Lights, Antarctica

Aurora Borealis, Iceland