Prof. King studies the dynamical structure and the population content of globular clusters. His current activities all involve images taken with the Hubble Space Telescope. One set of projects concerns measuring internal motions in globular clusters, using high-precision astrometric methods. Another activity is to follow the main sequences of globular clusters down to the lower limit of hydrogen burning. Past work dealt with dynamical modeling of star clusters (the "King models"), the structure and content of the Milky Way and other galaxies, and techniques of measurement and reduction of astronomical images.
Prof. King is a member of the National Academy of Sciences and a past President of the American Astronomical Society.