Caltech is a world-renowned science and engineering institute that marshals some of the world's brightest minds and most innovative tools to address fundamental scientific questions and pressing societal challenges. The Institute manages JPL for NASA, sending probes to explore the planets of our solar system and quantify changes on our home planet. Caltech also owns and operates large-scale research facilities such as the Seismological Laboratory and a global network of astronomical observatories, including the Palomar and W. M. Keck Observatories; and cofounded and comanages LIGO. Caltech is an independent, privately supported institution with a 124-acre campus located in Pasadena, California. In September 1891, Pasadena philanthropist Amos Throop rented the Wooster Block building in Pasadena for the purpose of establishing Throop University, a forerunner to Caltech. In November of that year, Throop University opened its doors with 31 students and a six-member faculty. Throop might have remained simply a good local school had it not been for the arrival in Pasadena of astronomer George Ellery Hale. The first director of the Mount Wilson Observatory, Hale became a member of Throop's board of trustees in 1907 and began molding the school into a first-class institution for engineering and scientific research and education. By 1921, Hale had been joined by chemist Arthur A. Noyes and physicist Robert A. Millikan. These three men set the school, which by then had been renamed the California Institute of Technology, firmly on its new course. Millikan and his successors (Lee DuBridge, Harold Brown, Marvin Goldberger, Thomas Everhart, David Baltimore, Jean-Lou Chameau, and now Thomas F. Rosenbaum) have led the Institute to its current academic and scientific preeminence.