This course is intended for anyone interested in learning about scientific theories of the universe, from ancient to modern. The course is organized around the question: What is science, and how does it differ from other human endeavors like philosophy, art, and religion? We will ponder this question by examining the shifting boundary between science and these other areas over the centuries, with a particular focus on the historical development of astronomy and cosmology. Along the way, we will explore how it became possible to estimate the distances to planets, stars, and the most distant galaxies, to map out the life-cycles of stars and galaxies, and to estimate the age of the Universe. We will also explore how we might search for life elsewhere. We will discuss the theories of relativity and quantum mechanics, along with black holes, time warps, wormholes, dark matter, dark energy, cosmic inflation, and other fascinating ideas.