Lecture, three hours; discussion, one hour. Designed for senior Astrophysics and Physics majors. Properties of star clusters and galaxies, with particular emphasis on Milky Way galaxy. Clusters and superclusters of galaxies. Extragalactic distance scale. Quasars and active galaxies. Topics in cosmology, including expansion of universe, microwave background, galaxy formation from primordial fluctuations, and observational constraints on Big Bang. P/NP or letter grading.