Physics has revealed the secret birth of the particles that cause auroras

© JHU/APLЗонды RBSP designed to study the Earth’s radiation beltsPhysics has revealed the secret birth of the particles that cause auroras© JHU/APL

The electron fluxes in the Earth radiation belts are the result of interactions of cosmic rays with atoms in the upper atmosphere of the planet, «knocked out» of these neutrons, said in an article published in the journal Nature.

«We were the first to capture the birth of these high-energy electrons at the inner edge of the van Allen belts. We were able to solve the mystery over which physicists have puzzled for almost six decades,» said Singling Lee (Xinlin Li) from the University of Colorado at boulder (USA).

The earth, unlike Venus and other planets in the Solar system, has its own magnetic field, which is generated by the movement of the liquid streams of metal in its core. This magnetic field plays the role of a «shield», which reflects cosmic rays, charged particles of high energies, and protects the Earth from solar wind and coronal mass ejections on the Sun.

Traces of its existence are the so-called van Allen belts — two regions at altitudes of about 6 thousand and 60 thousand kilometers from the Earth’s surface, where there are a large number of protons and electrons of high energies, «caught» the Earth’s magnetic field and moving in a kind of a magnetic trap. Their interaction with the atmosphere produces beautiful polar lights, and, in times of solar flares, caused radio interference and other technical problems.

One of the main mysteries of the van Allen belts since their discovery in 1958, is where are the electrons and protons of high energies that inhabit the radiation shield of the earth and generates a flash at the poles of the planet. As Lee notes, scientists have long suspected that their source is cosmic rays, colliding with atoms in the atmosphere, however, unequivocal evidence they had.

An additional problem is that cosmic rays generated by supernova explosions and active pulsars, bombard the Earth with approximately equal frequency, whereas the number and properties of electrons in the van Allen belts can change dramatically very fast. This leads many researchers to doubt that these electrons arise from the decay of neutrons which cosmic rays «knock out» from atoms of nitrogen and oxygen.

To test these ideas, Li and his students have collected microsatellite CSSWE, equipped with miniature counterparts of the detectors of electrons and protons that have been developed at the University of Colorado for probes RBSP, launched by NASA in August 2012 to investigate the structure of the van Allen belts.

This satellite was launched to a lower orbit and he have not studied the inner layers of the van Allen belts, and the lower edge of the first part, where, as scientists suggested, should be born electrons and protons during the collisions of gas molecules and «visitors from outer space».

Such as collision, as the scientists explain, should lead to the birth of protons and electrons in very narrow energy ranges, making them easy to count, how often cosmic rays collide with atmospheric atoms, and to understand the role they play in filling the van Allen belts and how they get there.

As shown by these measurements, these electrons do occur in large quantities at a height approximately equal to the radius of the Earth, and the speed of their formation and their properties remained constant in all regions and at all altitudes. This speaks in favor of the fact that they do produce cosmic rays.

Moreover, this is evidenced by the number of electrons recorded by CSSWE, as scholars have noted, almost perfectly corresponds to how many neutrons would produce cosmic rays. All this, accordingly, suggests that almost all electrons involved in the birth of the Aurora are really «cosmic» origin.

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