ASTR 104
The Milky Way Galaxy and the Universe Beyond Spring 2026
Division III

How, when, and why was the Universe created? How has it evolved to its state? And what is our place in the Universe? Over the course of history, humanity has offered ever-evolving answers to these questions. In the 16th century, Copernicus posited that the Earth is not, in fact, the center of the Universe. In the 17th century, Galileo noticed that stars are not spread randomly across the night sky but are instead concentrated in a disk–what we now call the Milky Way. A century ago, Edwin Hubble discovered not only that the Universe contains a multitude of other such galaxies, but that the Universe itself is expanding (and thus must have had a beginning). Our understanding of the Universe continues to evolve to this day, and the past decades have yielded a multitude of new ideas and unsettling discoveries: from the invisible and intangible “dark matter” that makes up the majority of our Universe, to the Universe’s accelerating expansion driven by a mysterious “dark energy,” to the hypothesis that the Universe almost instantaneously exploded into existence via a period of rapid “inflation.” In this course, we will study these and other phenomena, exploring the central observations, astronomers, and physical principles that guide our modern understanding of the cosmos.