Radioactive particles from huge solar storm found in Greenland

Discovery raises questions about emergency plans in place for severe space weather

Traces of an enormous solar storm that battered the atmosphere and showered Earth in radioactive particles more than 2,500 years ago have been discovered under the Greenland ice sheet.

Scientists studying ice nearly half a kilometre beneath the surface found a band of radioactive elements unleashed by a storm that struck the planet in 660BC.