In 1959, he emigrated to the United States and went to work at the California Institute of Technology. In the beginning, he worked on theories about the mass distribution and dynamics of galaxies. Of particular note from this period was his formulation of what has become known as the Schmidt law, which relates the density of interstellar gas to the rate of star formation occurring in that gas. He later began a study of the light spectra of radio sources. In 1963, using the famous 200-inch reflector telescope at the Palomar Observatory, Schmidt identified the visible object corresponding to one of these radio sources, known as 3C 273 and also studied its spectrum. While its star-like appearance suggested it was relatively nearby, the spectrum of 3C 273 proved to have what was at the time a high redshift of 0.158, showing that it lay far beyond the Milky Way, and thus possessed an extraordinarily high luminosity. Schmidt termed 3C 273 a "quasi-stellar" object or quasar; thousands have since been identified.