Auroas Essay Example | Topics and Well Written Essays - 2750 words

Auroas - Essay Example The subject of these auroras and related issues such as the aurora borealis and aurora australis are of great significance and importance, and in order to come to a clearer and more knowledgeable understanding of these issues, the related information must be addressed thoroughly. The aim of this paper is to discuss all of this, as well as explain how each of the sub-subject matters are related and correlated. This is what will be dissertated in the following. Auroras are caused by high energy particles from the solar wind that are trapped in the Earth's magnetic field. These particles, as they spiral back and forth along the magnetic field lines, come down into the atmosphere near the north and south magnetic poles where the magnetic field lines disappear into the body of the Earth. "The delicate colors are caused by energetic electrons colliding with oxygen and nitrogen molecules in the atmosphere. This excites the molecules, and when they decay from the excited states they emit the light that we see in the aurora." (Csep, n.d.). More intricately, the sun sends a constant stream of charged particles, known as a solar wind, into space; then these energized particles interact with a protective magnet shield that shrouds the planet Earth. The Earth's magnetosphere is a sort of shield, which is made up of invisible lines that radiate out into space from the northern and southern poles. The charged particles squeeze the magnetic field into a teardrop shape, and "In the magnetosphere, researchers say, the interaction creates electric fields and electromagnetic waves that transfer their energy to electrons, which then plunge into the atmosphere." (Britt, 2000). "The aurora varies in intensity from brightness equal to that of the Milky Way up to the equivalent of a full Moon," says climatologist Jan Curtis, who photographs auroras from his home in Alaska. "Colors range from mostly greens to reds, and take on the forms of discrete rays, homogenous brands and arcs, or diffuse glowing clouds. Their movement can be stationary, or zip across the entire sky in seconds." (Britt, 2000). Primary auroral particles have energies between few tens eV and few hundred keV, being higher on the nightside than on dayside. Some of them are even accelerated in the field-aligned direction, which indicates the presence of a special auroral acceleration region. "It can be shown that for 2 keV (100keV) electrons the maximum ionization rate occurs at the altitude of about 130 km (85 km)." (Space, 1998). Whereas the average ionization potential of atoms and molecules is about 15 eV, some experimental data show that fast electrons and protons produce one ion-electron pair per 36 eV, and some excess energy is also left for the product electron; this is what leads to electron heating when the energy is being distributed through and among the ambient electron gas. Auroras are considered to appear as "a glow observed in the night sky, usually the polar zone." (Wikipedia, 2006). It is for this reason that some scientists call auroras 'polar auroras' or 'aurora polaris'. In more northern of latitudes, this occurrence is known as 'aurora borealis', which is Latin for