Chronicles the productive scientific career of Subrahmanyan Chandrasekhar, one of the 20th-century's distinguished astrophysicists. Among Chandrasekhar's many discoveries were the critical mass that makes a star too massive to become a white dwarf and the mathematical theory of black holes. In 1983 he shared the Nobel Prize for Physics for these and other achievements. Over the course of more than six decades of active research Chandrasekhar investigated a dizzying array of subjects. In this collection, ten eminent scientists evaluate Chandrasekhar's contributions to their own fields of specialization. Donald E. Osterbrock closes the volume with a historical discussion of Chandrasekhar's interactions with graduate students during his more than quarter century at Yerkes Observatory.