Dr Helen Mason explores what causes solar activity and what we are learning about the Sun from space observations in the ultraviolet and X-ray wavelength ranges. The Sun goes through an 11 year cycle of activity. For the past few years it has been very quiet, but now it is becoming active again, with huge explosions and solar flares which shoot very hot material into space at extremely high speeds. This hot gas can hit the Earth's atmosphere, and cause chaos with modern technology, knocking out satellites, affecting communications, even causing major electrical black-outs. Scientists are currently observing the Sun from space with several different spacecraft: Hinode, Stereo, the Solar and Heliospheric Observatory and the Solar Dynamics Observatory. The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter