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The Aurora Borealis
Polar auroras are an optical phenomenon of the earth's atmosphere characterized mainly by iridescent bands of red, green and blue light visible in the sky.
They are some of the most beautiful phenomena that can be observed in the high altitude atmosphere; they are normally visible above the seventy-fifth degree of latitude, but can extend to even lower latitudes, including Scotland, many areas of the Scandinavian peninsula, Japan, the United States, Australia and South America. They usually occur at heights ranging between 100 and 200 kilometers, but can sometimes reach 1000 kilometers. They appear simultaneously in both hemispheres and are known as “Aurora Borealis" in the northern hemisphere and "Aurora Australis" in the southern hemisphere.
Auroras are generated by elementary particles emitted by the sun, which, when they arrive charged near to earth, are affected by the earth's magnetic field. Like a magnet, the earth's magnetic field lines converge near the poles where the particles of the solar wind are channeled with great efficiency and manage to significantly penetrate the upper atmospheric layers. As they enter increasingly dense regions of the atmosphere, collisions increase between the solar wind particles, charged with the atoms and molecules making up the atmosphere, which, when stimulated, emit light at various wavelengths.
They can occur in very varied shapes and colors and change quickly in time and space. The geographic extent to which the phenomenon is visible depends on the intensity of the "solar wind" and is linked to the loss of mass (plasma) of our star. This loss is not constant over time, but variable and it is associated with very violent phenomena occurring in the outermost layers of the sun. Although they are not very regular, these violent phenomena follow a cycle of around eleven years, during which there is a maximum and minimum of this type of activity. During the maximum phases of the solar cycle, the likelihood of seeing the Aurora Borealis, even at very low latitudes (in 1999 it was seen in Friuli-Venezia Giulia!), increases significantly.
Pilots on alert
The interactions between the solar wind and the earth's magnetic field produce considerable alterations in the ionosphere and this can significantly compromise radio communications. Serious damage can often also be caused to electricity transport systems, for example power lines. Damage is more frequent and serious in the circumpolar regions where the phenomena that generate auroras are more intense.
In conjunction with certain international bodies, Alitalia monitors, at planetary level, the element that forms the basis for these light phenomena: sun storms. The greater the intensity of the phenomenon, the higher the risks of it having a negative impact on the correct operation of certain pieces of navigation equipment. In the most intense cases, ad hoc warnings are issued as a precaution, banning flights in the regions concerned.
You never get used to the beauty
We pilots, and in some cases our passengers too, often see these natural phenomena, especially during the intercontinental flights that our company makes daily in various parts of the world. I must admit that, even though I have seen it before, I am always fascinated by such vast and spectacular "special effects" that nature presents in the starlit sky.
Each time, never-before-seen shades, effects and colors are revealed and remain imprinted in your mind. And each time it is always a fascinating spectacle.