Three-dimensional reconnection on the Sun

A brief review is given of the theory of magnetic reconnection in three dim ensions. The key elements of a three-dimensional null point are its spine a nd its fan, which consist, respectively, of a field line and a surface of f ield lines that pass through the null, The fans of two nulls intersect in g eneral in a field line called a separator that joins the nulls. Several dif ferent types of reconnection have been proposed. namely: spine reconnection , fan reconnection, separator reconnection and quasi-separatrix layer recon nection. In addition, a new exact solution for reconnective annihilation ha s been recently discovered. A summary is also given of the impressive evide nce of reconnection at work on the Sun provided by a range of observations from the Yohkoh and SOHO satellites, both of solar flares and of coronal he ating events.