Solar filaments. Composite Solar Dynamics Observatory (SDO) image showing solar filaments forming an arrow shape (pointing to the right) on the surface of the Sun. Filaments are cooler clouds of solar material suspended above the sun's surface by powerful magnetic forces. They can float for days without much change, though they can also erupt, releasing solar material in a shower that either rains back down or escapes out into space, becoming a moving cloud known as a coronal mass ejection (CME). If straightened out, these filaments would be around 1 million miles long, about the same as the Sun's diameter. Imaged using combined wavelengths of extreme ultraviolet (UV), on 28th May 2015.