The Smithsonian Astrophysical Observatory, a bureau of the Smithsonian Institution, has been teamed with the Harvard College Observatory for many years to run the Harvard-Smithsonian Center for Astrophysics, a research facility based in Cambridge, Massachusetts, with some three hundred scientists. The Lowell Observatory, based in Flagstaff, Arizona, was founded by Percival Lowell (1855–1916) a century ago to search for, among other astronomical phenomena, Planet X; today, it remains a major center for astronomical research. Perhaps the largest and most prestigious private observatory today is the Observatories of the Carnegie Institution of Washington. The wealthy industrialist Andrew Carnegie (1835–1919) founded the Carnegie Institution in 1902, and it has been a major force in astronomical research ever since. The Carnegie Observatories currently operate facilities in Pasadena, California, and Las Campanas, Chile, which is home to the twin Magellan Telescopes. The Carnegie Institution’s Washington offices are also home to the Department of Terrestrial Magnetism, which has had a very strong astronomical presence for nearly a century. Astrophysicists there have pioneered research on dark matter, astrobiology, and exoplanets.