The largest telescope in the world from 1948 through the 1970s, the Hale reflector, is located at the Palomar Mountain Observatory near Pasadena, CA. Operated by the California Institute of Technology, Palomar also has a 60-inch photometric reflector and a 48-inch Schmidt telescope. Among the work done at Palomar was confirmation that nebulae outside the Milky Way are galaxies like our own. Ongoing work at the observatory includes studies of the rate of expansion of the universe and the mean density of the universe, the history of star formation in the Milky Way, and interstellar matter.