Explore the vast realm of galaxies in this comprehensive 2.5-hour lecture from the "Astronomy: Exploring Space and Time" course. Delve into topics such as the Milky Way, dark matter, galactic centers, galaxy collisions, and large-scale structures. Investigate the properties and distances of galaxies, learn about active galaxies and quasars, and examine cosmic expansion and dark energy. Gain insights into the formation of universal structures and the evidence supporting dark matter theories. This in-depth exploration of galactic astronomy is led by Professor Chris Impey from the University of Arizona and Steward Observatory.