An international team of scientists discovered that solar storms can be much more powerful and devastating than we know. By analyzing traces of solar storms in ice cores from Greenland and Antarctica, researchers concluded that Earth was hit by two extreme solar storms over a thousand years ago.

Solar storms are eruptions on the Sun which cause the emission of a huge amount of particles. If the emitted particles hit the Earth they engage in interaction with our planet's magnetic field. This interaction causes the particles to gather around Earth's poles therefore causing the northern or southern polar lights, the so-called auroras

Apart from this amazing and visually appealing phenomena, solar storms can also cause major power outages, and can lead to satellites and communication systems break downs. Several extreme solar storms have been observed in the last 40 years, which have led to power outages across major inhabited areas of the planet. One event of such strength was documented in March 1989 in Canada and in October 2003 in Sweden.

However, new discoveries made by a team of scientists from Sweden, Switzerland, Denmark and US suggest the solar storm events can be at least ten times larger than the ones we're familiar with so far, and our planet has faced at least two events of such violent force more than 1 000 years ago.

"If such enormous solar storms would hit Earth today, they could have devastating effects on our power supply, satellites and communication systems," says Raimund Muscheler at the Department of Geology, Lund University.

Traces of cosmic rays, such as low levels of radioactive carbon, from the Galaxy and the Sun can be found across the planet. The research team has analyzed traces of solar storms found in ice cores from Greenland and Antarctica and compared them with previously discovered traces of a rapid increase of radioactive carbon in tree rings dating to AD 774/775 and AD 993/994 the cause of which has been unconfirmed until now.

"In this study we have aimed to work systematically to find the cause for these events. We have now found corresponding increases for exactly the same periods in ice cores. With these new results it is possible to rule out all other suggested explanations, and thereby confirm extreme solar storms as the cause of these mysterious radiocarbon increases," said Raimund Muscheler.

New results also provide the first reliable assessment of the particle fluxes connected to solar storm events, which is extremely significant for the future planning of reliable electronic systems: "These solar storms by far exceeded any known events observed by instrumental measurements on Earth. The findings should lead to a reassessment of the risks associated with solar storms," concluded Raimund Muscheler.

Reference:

"Multiradionuclide evidence for the solar origin of the cosmic-ray events of AD 774/5 and 993/4" - Florian Mekhaldi, Raimund Muscheler, Florian Adolphi, Ala Aldahan, Jürg Beer, Joseph R. McConnell, Göran Possnert, Michael Sigl, Anders Svensson, Hans-Arno Synal, Kees C. Welten, Thomas E. Woodruff - Nature Communications (2015) - doi:10.1038/ncomms9611

Featured image: X Class Solar Flare sends 'shockwaves' on the Sun, March 7, 2012. Image credit: NASA Goddard Space Flight (Flickr-CC)