Exciting and Productive
The Yerkes Observatory 40-inch telescope represented the limit of refractor applications and Hale directed his considerable energy to the next stepa 60-inch reflector telescope. This time Hale's much larger campaign involved financing by the Carnegie Institution of Washington and the Hale family moved to Pasadena, close to Wilson's Peak, an ideal observation area. The independent observatory opened at Mount Wilson in 1904 with the largest telescope in the world. Hale resigned from the University of Chicago and his solar research was undertaken by scientists who moved over from the Yerkes Observatory. In the same year the International Union for Cooperation in Solar Research was created.
The work begun at Mount Wilson was exciting and productive. Matching astronomy and physics to build instruments, gather data, and test conclusions in the laboratory made research advance quickly. During this time Hale was able to experimentally verify his greatest discovery: spectral displacement in sunspots is caused by the Sun's magnetic field.
The civic-minded George Hale also devoted time to the progress in the city of Pasadena, serving on boards and commissions as the city rapidly expanded. As a 1907 trustee of the multi-purpose Throop Polytechnic Institute, he led its reorganization into a post-secondary science and engineering school which became the world-renowned California Institute of Technology with its emphasis on fundamental research.