Polar lights

Have you ever watched Polar lights? An unforgettable sight! By the way, for this it is not necessary to turn into a polar explorer. Polar lights are often visible even in Moscow or Paris. There have been cases when they were observed in Egypt. But, of course, in the near-polar regions polar lights appear more often. And, in addition, they are brighter, colorful, diverse. Some polar auroras are colored rays radially diverging from a certain center. Others resemble luminous majestic draperies - details of fantastic heavenly scenery. Often in the sky arcs, bands, strips are formed. Often all this is in rapid motion with the change of colors.

Have you ever watched polar lights? An unforgettable sight! By the way, for this it is not necessary to turn into a polar explorer

The polar lights, which in ancient times seemed to be mysterious phenomena of nature, are now thoroughly studied and their close connection with the Sun. Polar lights are the glow of rarefied air at altitudes from 100 to 1000 km. Red and green colors, most characteristic of auroras, are formed by oxygen atoms, especially those emitting precisely these rays. By their physical nature polar auroras are quite similar to the glow of rarefied gases in the discharge tubes of advertisements. And there, in the upper atmosphere, here, in these creatures of human engineering, the atoms of gas are bombarded by corpuscles. The energy of the corpuscles is transferred to the atoms of the gas, as a result of which the electrons jump from one energy level to the other, and the gas begins to glow with "cold" light.

The fact that the polar lights is caused by the Sun is also proved by direct observations. During the polar auroras (and they sometimes last for hours), a line of hydrogen is visible in the spectrum of these auroras. It is markedly shifted to the violet end of the spectrum - hence, the protons that generate it fly into the atmosphere at a speed of at least 1000 km/sec. These are corpuscles emitted by the Sun, and the air glows under the effect of "bombarding" it with solar protons. When in 1958 the Americans blew up a nuclear bomb at an altitude of 60 km, the protons and electrons that emerged during the explosion were captured by magnetic field of the Earth. Quickly moving along the lines of force, they collided with the atoms of the air and made them shine. So for the first time accidentally man created artificial polar lights. Similar phenomena were observed in other high-altitude nuclear explosions. Fortunately, such experiments are no longer repeated, but they, though in miniature, produced what is constantly created by the Sun. The frequency and intensity of polar lights is higher than more active Sun. Magnetic storms and auroras are inseparable. They arise and disappear almost simultaneously.

Since ionization by charged particles occurs most efficiently at the end of the path, the particles and density of the atmosphere decrease with increasing altitude, then the height of the appearance of polar lights depends quite strongly on the parameters of the planet's atmosphere, so, for the Earth with its rather complex atmospheric composition, red light of oxygen is observed at heights of 200-400 km, and the combined glow of nitrogen and oxygen - at an altitude of about 110 km. In addition, these factors determine the shape of auroras - a blurred upper and rather sharp lower boundary.

Polar lights in spring and autumn appear much more often than in winter and summer. The peak of frequency falls on the periods closest to the spring and autumn equinoxes. During the aurora, a huge amount of energy is released in a short time. So, for one of the disturbances registered in 2007, there were 5*1014 joules, about the same as during the earthquake with a magnitude of 5,5.

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