Comet Hale-Bopp. Optical image of comet Hale-Bopp showing its gas and dust tails. The comet's gas or ion" tail (blue) consists of ionized glowing gas blown away from the comet head by the solar wind. The dust tail (white) consists of grains of dust pushed away from the comet head by the radiation of sunlight. A comet's tails always point away from the Sun and these tails may be millions of kilometres in length. Comet Hale-Bopp was discovered on 23 June 1995. At lower right is the pink North America nebula, with the bright star Deneb (Alpha Cygni) to its right. North is at top. Photographed on 8 March 1997 from Mount Pinos in California, USA."