Examines the properties of galaxies, large-scale structure in the universe, and cosmological models. The basic aspects of galaxies are explained, orbital theory, spiral arms, the missing mass in galaxies, galaxy evolution, and the starburst phenomenon. The clustering of galaxies, the hot intracluster medium and the dynamical evolution of clusters. Expansion of the universe, the cosmic microwave background, the inflationary universe, Big Bang nucleosynthesis, and the origin and growth of structure in the universe.