is the glow of the upper rarefied layers of the atmosphere, caused by the interaction of atoms and molecules at altitudes of 90-1000 km with charged particles of high energies (electrons and protons) invading the terrestrial atmosphere from space. Collisions of particles with the components of the upper atmosphere (oxygen and nitrogen) lead to excitation of the latter, i.e. to a transition to a state with a higher energy.
Return to the initial, equilibrium state occurs by emitting photons of light of characteristic wavelengths, i.e. aurora borealis. It is observed mainly in the high latitudes of both hemispheres in the oval belts (auroral ovals) that surround the magnetic poles of the Earth, at latitudes of 67-70 degrees. In times of high solar activity, the boundaries of the polar aurora expand to lower latitudes – 20-25 degrees south or north.
Polar lights are most often observed in winter.
Apparently, this view has developed from the fact that the aurora in Russia is often called the “northern lights” (by the name of the hemisphere where it is observed), and the north is associated with frost, snow and, accordingly, in winter. In fact, auroras most often occur in the spring and autumn, in periods close to the spring and autumn equinox and are repeated as cycles, whose duration is approximately 27 days and 11 years.
Polar lights are produced by solar perturbations.
This confirms the cyclical nature of auroras, coinciding in their highest peaks with the 27-day rotation of the Sun and 11-year fluctuations in solar activity, and their concentration in the zone of perturbations of the Earth’s magnetic fields.
Polar lights are just a light in the sky.
It is accompanied by a huge amount of energy, which is released in a relatively short period of time. The strength of radiation can sometimes be equal to 5-6 earthquake. Pulsating polar lights can also be accompanied by weakly sibilant sounds or a light crackle.
Forms of auroras are different.
Polar lights are observed in various forms and forms: spots, uniform arcs and stripes, pulsating arcs and surfaces, glimpses, flashes, rays and radiant arcs, crowns. The glow of the aurora usually begins with a continuous arc, the most widespread form of aurora borealis, and in the case of an increase in brightness, other, more complex forms may acquire.
The color of the aurora depends on its intensity.
The intensity of glow of the aurora is determined according to the accepted international scale within the limits of I-IV points. Shines with a low intensity of luminescence (from I to III points) do not seem to the human eye in many colors, since the color intensity in them is below the threshold of our perception. Polar lights with intensity in IV point and III (near the upper boundary) are perceived as colored – more often as yellow-green, less often – red and violet. It is interesting that most of the radiation is emitted by the main components of the high layers of the earth’s atmosphere – atomic oxygen, which colors the auroras in yellowish tones, gives them reddish radiance or brings to the general spectrum a green line and molecular nitrogen responsible for the main red and violet colors of one of the most beautiful celestial phenomena.
Through the polar lights you can see the stars.
Since the thickness of the aurora is only a few hundred kilometers.
Polar lights can be seen from outer space.
And it is not only visible, but much better than from the surface of the Earth, because in the cosmos to observe the aurora bore neither the sun nor the clouds, nor the distorting influence of the lower dense layers of the atmosphere. According to the cosmonaut, from the ISS orbit the aurora borealis look like huge green constantly moving amoeba.
Polar lights can last for days.
Or maybe only a few tens of minutes.
Polar lights can be observed not only on Earth.
It is believed that the atmospheres of other planets (for example, Venus) also have the ability to generate auroras. The nature of the polar auroras on Jupiter and Saturn is similar to the nature of their earthly brethren according to the latest scientific data.
Polar lights can be induced artificially.
For example, using a nuclear explosion in the high atmosphere. What was done somehow by the US Department of Defense. The American military managed to achieve a radiance from the arc of crimson color and smoothly shifting from red through violet to green rays. Based on the color palette of artificial auroras, a theory was born that the cause of their appearance lies in the excitation of oxygen and nitrogen contained in the atmosphere and their collision with charged particles released as a result of a nuclear explosion.
Polar lights can be caused by rocket emissions.
However, this phenomenon is usually called an artificial glow, since the causes of its occurrence are close to those that cause a natural glow of air.