Professor Yung’s research interest consists of six major overlapping areas: planetary atmospheres, planetary evolution, atmospheric chemistry, atmospheric radiation, astrobiology and global change, with a strong emphasis on interaction and synergy among modeling, laboratory experiments and field observations, often in collaboration with colleagues at Caltech and the Jet Propulsion Laboratory (JPL).

        Planetary scientists study the earth, planets in our solar system and extra-solar planets, as a matter of intellectual curiosity, as a window on the origin and evolution of the solar system, and also as laboratories in which theories and models of our own atmosphere can be tested.  Professors Yung’s research has covered the planets Mars, Venus, Jupiter, Uranus and Neptune, the moons Io (Jupiter), Ganymede (Jupiter), Callisto (Jupiter), Titan (Saturn) and Triton (Neptune), as well as extra-solar planets such as HD209458b.  He has studied a wide variety of gases in these atmospheres, including H₂, O₂, O₃, N₂, N₂O, H₂O, HDO, CO, CO₂, halogens, methane and higher hydrocarbons, ammonia, sulfur compounds and aerosols.

        In his work on planetary observations, Professor Yung collaborates with spacecraft teams. He is a co-investigator on the Ultraviolet Imaging Spectrometer (UVIS) Experiment on the Cassini mission to Saturn (1987-present), the Orbital Carbon Observatory-2 (OCO-2), a project to map CO₂ concentrations for the Earth (launch 2013) and the Mars Atmospheric Trace Molecule Occultation Spectrometer (MATMOS, launch 2016).  He is an Interdisciplinary Scientist for Venus Express, an European Space Agency mission (launched in 2005). 

        Professor Yung is the co-author of two important books: Atmospheric Radiation: Theoretical Basis with R.M. Goody (Oxford University Press 1989) and Photochemistry of Planetary Atmospheres with W. B. DeMore (Oxford University Press 1999).  He is the author or co-author of over 250 peer-reviewed scientific articles.