Solar flare. Composite Solar Dynamics Observatory (SDO) image showing a solar flare and coronal mass ejection (CME, lower left) erupting from the surface of the Sun on 31 August 2012. The CME travelled at over 1400 kilometres per second. It did not travel directly towards Earth, but did connect with Earth's magnetic environment, or magnetosphere, causing aurora to appear on the night of 3 September 2012. This is a composite of the SDO images obtained at wavelengths of 304 and 171 angstroms.