A Parhelion (plural Parhelia, from "beside the sun", also called a 'Mock Sun') is an atmospheric phenomenon that creates bright spots of light in the sky, often on a luminous ring or halo on either side of the sun.

Parhelia are formed by plate shaped hexagonal ice crystals in high and cold cirrus clouds or - during very cold weather - by ice crystals called diamond dust drifting in the air at low level.

A realtime performance piece made for Electrovision Cinema, The Roxy Screen, London, September 2009.