Butterfly nebula (IC 1318). Composite optical image of the emission cloud IC 1318, a giant HII region (a region of ionised interstellar atomic hydrogen) and one of the brightest of all the emission clouds in the Cygnus complex. The region seen here spans over 100 light years and the bright star seen at its centre is a class F8 star known as Sadr, or Gamma Cygni. Gamma Cygni lies only 750 light years from Earth, whereas IC1318 is much more distant at 5000 light years. Image based on data obtained by the Oschin Schmidt Telescope, Palomar Mountain, USA, and the UK Schmidt Telescope, Siding Spring Observatory, Australia, for the Digitized Sky Survey.