A sudden geomagnetic storm, the strongest in the past 18 months, was caused by the Sun.

The geomagnetic storm that began on April 5 still continues, although it is subsiding. The maximum strength is most likely over. The storm has reached geomagnetic K-index 7 out of 10, the strongest in the past 540 days, since October 2008.

According to a warning issued by Russian scientists on the website of the space observatory Tesis, the storm of such strength may “affect global power systems requiring voltage correction and cause false security systems alarms.” Spacecrafts may be damaged, as well as communication systems and satellite navigation systems. Northern Lights will be observed even in midlatitudes. Acute cardiovascular diseases are not ruled out.

It is hard to say how exactly the planet was damaged. Exceptionally bright Northern Lights were observed from the orbit by astronauts working at the ISS. Japanese member of the team Soiti Noguti even took a picture of this bright sight. In the picture, the station looks like it is floating in outbursts of fire.

The scientists were surprised that there were no precursors for this strong geomagnetic storm. It was caused by certain processes on rather quiet Sun. For instance, on April 3 there was an outburst on the Sun, but it was so weak that it was not even paid much attention to. Yet, the outburst did not subside quickly as it usually happens but lasted for over seven hours. It was catastrophically long and it was not considered in the forecasts.

Scientists stated that “a huge energy that was to be released during the outburst was underestimated. In general, the incident shows that the connection between outbursts on the Sun and emissions of solar matter that causes geomagnetic storms cannot be considered a solved issue of solar physics.”

The beginning of the storm was rather weak. Later the state of magnetosphere radically changed.

Geomagnetic K-index reflecting geomagnetic fluctuations has increased from 4 to 7 in 3 hours. According to the American classification, it was G3 storm, a strong one, of the last, red, level of danger.

It is hardly likely that the cataclysm will repeat, but it cannot be ruled out completely. Unpredictability of the Sun is scary. The shocking scenario described by specialists of the American Academy of Sciences does not look that unrealistic. In the report “ Severe Space Weather Events--Understanding Societal and Economic Impacts: A Workshop Report ” they predict maximum solar activity by 2012 and, respectively, strongest outbursts and geomagnetic storms. They envisage that fluctuations will damage high-voltage power lines and transformer substations, which will leave the planet without electricity.

Unfortunately, this is not that unrealistic. Similar damages, if not even worse ones (remember "2012" movie), can be caused by long stronger outbursts of 7 hours.