A new era of discovery is unfolding in astronomy. The recently-launched James Webb Space Telescope has revealed observations of the earliest galaxies in the Universe, showing how galaxies evolved from clouds of gas to the vast stellar structures we see today. Meanwhile, the Legacy Survey of Space and Time is beginning a sweeping, weekly scan of the entire sky, delivering an unprecedented view of our own cosmic neighborhood. Galaxies in the present day span an astonishing range—from giant ellipticals filled with ancient stars to miniature galaxies orbiting much larger companions.

Our own Milky Way galaxy provides our cosmic environment--the stellar and gaseous surroundings within which the Sun and the Solar System were able to form and life on Earth evolved.  Understanding how it and other galaxies were shaped is, therefore, part of our origin story.  What drives the tremendous diversity of galaxies? Modern astronomy reveals that a galaxy’s story is shaped not just by its internal properties but also by the environment it grows up in and the interactions it has with other galaxies. In this talk, I will show how new observations in concert with cutting-edge simulations allow us to trace the life histories of galaxies--revealing how their surroundings, encounters, and mergers determine their evolution, their contents, and the stars they create.