The Sun is more active now than it has been for a millennium. The realisation, which comes from a reconstruction of sunspots stretching back 1150 years, comes just as the Sun has thrown a tantrum. Over the last week, giant plumes of material have burst out from our star's surface and streamed into space, causing geomagnetic storms on Earth.

The dark patches on the surface of the Sun that we call sunspots are a symptom of fierce magnetic activity inside. Ilya Usoskin, a geophysicist who worked with colleagues from the University of Oulu in Finland and the Max Planck Institute for Aeronomy in Katlenburg-Lindau, Germany, has found that there have been more sunspots since the 1940s than for the past 1150 years...