Powerful solar storms may be more common than previously thought, according to a study that found two massive storms hit Earth 219 years apart. They were several times stronger than previously recorded ones. Such storms could wreak havoc on technology. After studying ancient ice cores from Greenland and Antarctica, researchers at Lund University in Sweden found that the two solar storms hit Earth more than 1,000 years ago – the “red crucifix” storm in AD 774/775 and another in AD 993/994.

The study follows the work of researchers in 2012, when they found traces of a rapid increase of radioactive carbon in tree rings from those time periods. The 774/775 event corresponded with a text in an ancient Anglo-Saxon Chronicle, which referred to a “red crucifix” appearing in the heavens after a sunset.However, the causes for the increases in radioactive carbon were previously debated, with some believing the red crucifix was caused by a supernova, and others saying it was because a giant comet hit the sun. FULL REPORT