Palomar's 200-inch Hale telescope helped revolutionize modern astronomy -- and modern baking. Mirror makers spent nearly $1 million -- in 1934 dollars -- and still couldn't make a big enough quartz mirror. George Ellery Hale, who shepherded Palomar's creation as he had Mt. Wilson's, approached Corning Glass Works of upstate New York and asked for a 200-inch mirror made of a new glass blend called Pyrex. Changes in temperature make Pyrex expand and contract less than regular glass, so a Pyrex mirror is less prone to distortion problems, which had plagued Hale's 100-inch scope on Mt. Wilson.
After World War II-related delays, first light came Jan. 26, 1949. Edwin Hubble was the first to peer through the looking glass. A year later, a companion 48-inch scope began the first Palomar Observatory Sky Survey, which mapped the entire northern sky. The catalog would later become the basis for the Guide-Star Catalog used by the Hubble Space Telescope.
After three quarters of a century, Palomar is still making new discoveries. In 2007, scientists announced a new "adaptive optics" system to sharpen pictures taken from Palomar. The resolution exceeds the Hubble Space Telescope's by a factor of two.