The Michelson - Pease centennial

On the Monday evening of December 13, 1920, the first interferometric measurement of a stellar angular diameter was made. This talk commemorates the centennial of that landmark of observational astrophysics. It resulted from the collaboration of Albert Michelson, America’s first science Nobel laureate, and Francis Pease, the brilliant engineer-turned astronomer who designed the Mount Wilson 100-inch telescope and much of its instrumentation. This paper is a brief overview of how that measurement came to be made with a focus on the founding pioneers of interferometry and the small group of Mount Wilson astronomers who, in the 1920s, launched optical interferometry on the trajectory toward today’s facilities employing multiple-telescope, optical/infrared interferometric arrays.