Auroras - one of the most beautiful light phenomena in nature, so they attracted the attention of people throughout its history. Mention of auroras can be found in the writings of Aristotle, Pliny, Seneca and other ancient philosophers.
For a long time auroras seen as harbingers of disaster - epidemics, famine and war. For example, this phenomenon is linked to the fall of Jerusalem and the death of Julius Caesar. In any case, this saw the wrath of the gods or other supernatural forces.
In the Russian North aurora, or Northern Lights called pazoryami. The first of these words points to the similarity of this phenomenon with the dawns and the second comes from the word "poloshit" that is, disturb, harass, to raise the alarm. Indeed, during the auroral sky may be red as a fire. There are cases when the aurora was taken for red glow of fire and fire departments went to a huge blaze in the northern horizon.
Did you see the aurora in the southern hemisphere. English explorer James Cook (1728-1779) was one of the first who not only gave them a description of the southern hemisphere, but also drew attention to the fact that auroras occur at high latitudes in both hemispheres simultaneously.
The most common form of auroras are bands or spots resembling clouds . More intense glow takes the form of tapes, which decreases the intensity of the spots turn into. Tapes may also disappear without breaking into spots. Typical forms of the aurora, depending on their height. Tapes are usually run from east to west for thousands of kilometers, recalling the giant curtain.
The height of the curtain up to several hundred kilometers, and the thickness of only a few hundred meters. Therefore, such a transparent curtain, and through it we can distinguish stars. The lower edge of the curtain are usually sharply delineated and often tinted with red or pink color, and the upper, diffuse gradually disappears with height. Sometimes there is intense auroras, which cover most of the polar region and are characterized by a whitish-greenish glow. They are called squalls and the characteristic periods of high solar activity.
Brightness of lights are divided into four classes, which differ from each other 10 times. In the first class fall faint glow, similar to its brightness with the Milky Way . Radiance is the fourth class in brightness can be compared with the full moon.