Solar prominence. Optical photograph showing a loop prominence above the limb of the Sun. Loops are a class of active prominences, a variety of cloud- and flame-like structures which rise above the chromosphere or 'surface' of the Sun. The prominence is made of matter thrown from the surface by flares associated with sunspots, and drawn into a loop shape by powerful magnetic fields. Active prominences have lifetimes of a few hours, and can extend thousands of kilometres above the surface. They may also be the means for energy to travel from the chromosphere to the corona. Photographed on 15 August 1989.