MOSCOW, September 12. /TASS/. A yet another cloud of solar plasma is almost certain to reach the Earth on Thursday evening, triggering a geomagnetic storm, the Solar Astronomy Lab of the Space Research Institute of the Russian Academy of Sciences said on its website.

"According to results of a simulation <…> it will reach the planet with the likelihood of 99.9%," the Russian scientists said.

"Current calculations project the solar matter arrival <…> at around 10:00 p.m. Moscow time [7:00 p.m. GMT] on Thursday. The geomagnetic storm will reach its peak at around 3-4 a.m. [on Friday]," the statement says.

The scientists estimate the probability of a geomagnetic storm of G1 class (minor) or G2 class (moderate) at around 70%.

Solar flares are divided into five classes according to their X-ray strength: the smallest ones are A-class, followed by B, C, M and X. A0.0 class is equal to the radiation energy found in the Earth’s orbit, 10 nanowatts per square meter. Each letter stands for a 10-fold increase in energy output. As a rule, the flares, known as giant explosions on the sun, send solar plasma into space, and the clouds of these charged particles can bring about geomagnetic storms when reaching the Earth.