Molecules in the Atmospheres of Giant Planets and Comets

Spect roscopic observations of planets and comets from Earth-based observatories and spaceborne observatories during the last 3 decades have produced a lo ng list of molecules, radicals, and ions.The molecules in the atmospheres of giant planets and in the comae of comets have been considered to have a clue to the chemical evolution of the solar system from local interstellar clouds to the current solar system.The detection chronology of these molecules, and gradual improvement of our understanding of the chemistry of the molecules in the atmospheres are presented. Recent findings of new molecules in bright comets Hale-Bopp(C/1995 O1)and Hyakutake(C/1996 B2)using infrared and radio telescopes are highlighted.Implications of the abundances of these molecules and isotopic ratios in the atmospheres are discussed.