The Northern Lights

I had seen the Northern Lights (Aurora Borealis) only once before college. I remember laying in the driveway on a blanket next to a field of corn. They were distant, but frantic in their billowing curtain display of ivory shades.

Then I went to the Upper Peninsula and saw them with a frequency I may never again have the opportunity to experience. Reds, greens, whites, and even tints of purple appeared almost monthly above the cresting valley ridge on the other side of the canal.



But what causes these sporadic displays of electrical art? Well, it took me a long time to understand...so here goes:

The earth is surrounded by a magnetic field, originating from deep within its core. The field is strongest at its magnetic poles and weakest around the equator. The sun has a much larger magnetic field, which extends through the orbit of the earth. This field combined with fusion particles and radiation constitute solar wind.

Solar wind acts upon the earth's magnetic field in much the same way normal wind would act upon a pile of sand: the windward side is stretched and extended into the leeward side to create a tail like a melting comet.

The pressure exerted on the earth's magnetic field excites existing particles in the earth's atmosphere and actual creates a voltage gradient between the magnetic poles and the solar-blown "tail" of the earth's magnetic field.

This all takes place in the magnetosphere and as the voltage pushes the charged particles towards the poles, they amass and are pulled closer into the ionosphere. There, they react with ionosphere gases and the resulting reaction discharges visible electrical energy...light.

The stronger the solar wind, usually indicated by solar flares, or spastic jumps of solar activity beyond the sun's regular corona, the more brilliant the auroras.