N The sky over Bulgaria was illuminated by the aurora borealis on Sunday. The unusual sight of the red-tinted sky has sparked interest and many questions, as well as numerous posts on social media.
Unique: Aurora Borealis captured over Bulgaria (PHOTOS/VIDEO)
“From Bulgaria, such a phenomenon can only be seen in rare cases, after a powerful coronal mass ejection from the Sun, and if the eruption was in the direction in which the Earth is currently located”, said physicist Pencho Markishki from the Institute of Astronomy with NAO at the Bulgarian Academy of Sciences and from the Department of Astronomy at the Faculty of Physics of Sofia University “St. Kliment Ohridski”.
After the stream of charged particles travels the distance between the Sun and the Earth, it bombards the Earth’s magnetosphere and even bends it on its dayside. A geomagnetic storm is brewing that could disrupt radio communications, Markishki added.
Particles of solar plasma that enter the upper layers of the Earth’s atmosphere give rise to the auroras. In rare cases, when the process is very intense, the auroras can also be observed from lower latitudes, the physicist said.
A fiery phenomenon punched a hole in Earth’s magnetic field and produced a red glow
He explained that the intensity of the flow of charged particles, i.e. of the corpuscular radiation from the Sun, is estimated by the geomagnetic effect it causes, through the so-called planetary Kp index. It is a balometric (logarithmic) quantity that can have values from 0 to 9 and is determined by numerous ground-based geomagnetic stations located in the northern and southern hemispheres of the Earth.
Between 16:45 and 18:45 on Sunday, the Kp index reached and slightly exceeded a value of 8, after which it began to decline. This can be seen on the website of the National Institute of Geophysics, Geodesy and Geography at the BAS, Markishki specified. He pointed out that six-hour forecasts for this index can also be followed on the institute’s website.
According to physics, these phenomena are not harmless and deserve to be followed with special attention. Geomagnetic storms cause problems with radio communications, possible breakdowns in power systems and cable telecommunications networks. The reason is that additional voltage is induced in the wires of the power transmission networks, which can disable important facilities, Markishki said. The harmful effect is stronger the greater the total length of power lines in a country’s energy ring.
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Markishki recalled that in 1859, during a magnetic storm, the telegraph lines in the USA and in Europe went out of order. Also in 1972, a magnetic storm knocked out telephone lines in the US state of Illinois. In 1989, six million people in the Canadian province of Quebec were left without heating and lighting after a power outage, again due to a powerful magnetic storm.
While modern electronics and communications are becoming more and more complex and efficient, they are also becoming more vulnerable, and humanity already relies on them for literally everything, the specialist noted and explained that this shows why it is important to predict such phenomena.
“As in meteorology, for geomagnetic storms the forecasts are more certain up to two or three days ahead. Longer-term forecasts are based on periods of almost two weeks during which an active region on the solar surface, which is the source of the solar wind, is visible from Earth. This is in view of the 27-day synodic period of the Sun’s orbital rotation, that is, taking into account the movement of the Earth along its orbit around it. It also matters how long the given area will remain active on the Sun.”Pencho Markishki also said.
Source: Antoineta Markova/BTA