... What are Comet Tails Made Of? ... Credit Copyright: Jim Martin, Huntsville AL, Courtesy " Night of the Comet " ( NASA / Ames ) Explanation: The tail of comet Hyakutake , visible in this recent color image , is composed of dust and gas driven off the icy comet nucleus by the Sun's heat and blown away by the solar wind. ... Typical comet gas tail constituents are simple combinations of hydrogen, carbon, nitrogen, and oxygen - for example, H20 (water), CO (carbon monoxide), and CN (cyanogen) are common...