This spring, Director of the Carnegie Observatories Wendy Freedman spoke at the American Museum of Natural History’s Hayden Planetarium about astronomer Edwin Hubble’s discovery of the galaxies and the expansion of the universe, how astronomers measure vast distances, and how the Hubble Space Telescope is used to measure the size and age of the universe. Mike Shara, curator in the Department of Astrophysics, sat down with Freedman for an interview in the Hayden Planetarium to discuss the expansion of the universe, dark matter, and building the 25-meter telescope.