Although at first fleeting look the sun seems always the same, their activity is actually some activity cycles of about 11 years, discovered in 1843 Samuel Heinrich Schwabe, after 17 years of observations of sunspots.
It is often said that last eleven years have actually seen cycles of nine and fourteen others.
Right now we are approaching the maximum of solar cycle 24, which began on January 8, 2008, and whose peak is expected in mid 2013.
The X-Ray Sun Over 5.5 Years [Hinode / XRT] , the embedded video above, consists of images taken by the camera's X-ray observatory Hinode , shows how after a timid start -2009 was a year of very low solar activity- increasingly be seen more solar flares.
Thanks to the protection of the Earth's magnetosphere the effect of these usually is confined to spectacular auroras, although there may be cases where they cause failure, usually temporary satellites and spacecraft into orbit, or even problems in terrestrial communications systems or even electrical distribution networks.