X_class solar flare, 15th February 2011. This series of images, taken by NASA磗 Solar Dynamics Observatory, shows the powerful eruption from the bright sunspot 1158 centre. The extreme ultraviolet EUV image is surrounded by a SOHO spacecraft view of the solar corona orange at the same time. Solar flares are caused by the sudden release of magnetic energy stored in the Sun磗 atmosphere, which can lead to a coronal mass ejection, the release of a huge number of charged particles. Flares are categorised by the energy released, with X_class flares the most powerful. When they are directed at Earth, as this one was, the massive stream of charged particles can trigger blackouts, damage satellites and cause spectacular displays of aurora.