Comet Hale-Bopp, C1995 O1, sports two tails here: a blue ion tail and a white dust tail. Both are formed by material ejected from the nucleus, which is mostly water ice and dust. The ice is heated by the comet's approach to the sun, going directly from a solid to a gas, bypassing the liquid form. As the material from the nucleus is ejected it forms a gigantic cloud around the nucleus which we see as the coma. It then separates into the blue ion gas tail and the dust tail.