This image provided by NASA on March 7, 2012, combines observations made by NASA's Solar Dynamics Observatory in several extreme ultraviolet wavelengths, highlighting a bright X-class flare toward the upper left of the sun's disk on March 6. This flare was categorised as an X5.4, making it the second largest flare recorded - after an X6.9 on August 9, 2011. The full brunt of the storm is expected to hit Earth on Thursday and Friday, potentially disrupting power grids, GPS systems, satellites, and forcing planes to change their routes around the polar regions. Photo: NASA/AFP/Getty