One hundred years ago, Carnegie Observatories’ founder George Ellery Hale convened The Great Debate, in which leading astronomers of the day argued whether spiral nebulae were inside the Milky Way or beyond it. The latter was confirmed by Carnegie astronomer Edwin Hubble, using his observations at Mt. Wilson to discover the universe as we now know it to be. Today, astronomy is enmeshed in many “great debates,” including the nature of dark matter and dark energy, the expansion rate of the universe, and the formation of planetary systems. Dr. Mulchaey will discuss current controversies in these areas, and will describe how research in the coming decade may finally resolve some of astronomy’s biggest mysteries.

Dr. John Mulchaey: Director and Crawford H. Greenewalt Chair, Carnegie Observatories, Carnegie Institution for Science