R. Paul Butler, ’77

Dr. R. Paul Butler designed and built the iodine absorption cell system at Lick Observatory, leading to the discovery of five of the first six known extrasolar planets and setting a standard for precision Doppler studies worldwide. His work extended to building similar systems for major observatories like Keck, Anglo-Australian, and Magellan, with the original iodine cell destined for the Smithsonian Institution. Over 25 years, Butler and his collaborators have discovered hundreds of exoplanets, including the first transiting planet and the first terrestrial-mass planet, with their findings featured in major media outlets. His research has advanced Doppler velocity measurement precision from 300 meters per second in the 1980s to 1 meter per second in the 2010s, driving the search for Earth-like planets.