The History of Palomar Observatory in San Diego California

Palomar Observatory is located 5,570 feet above sea level in the Palomar Mountains of San Diego County, California. It is operated by the California Institute of Technology.

The 200 inch Hale telescope took twenty years to build. It was slowly built from 1928 to1948. It was named after the astronomer and philanthropist George Hale. He was awarded a grant of 6 million dollars from the United States government. The grant was based on the importance of the discoveries in astronomy and cosmology that would be made with the telescope.

Hale thought that it would take “only” six years to complete the building of the 200 inch telescope. But about one year after the project had started in October 1929, the stock market crashed. During the years of the Great Depression caused by the Great Crash several important decisions about the building of the telescope were made.

One of the features planned for the telescope was a push button mechanism that could direct the telescope to find and follow a star, planet, comet, etc. There was also a built in mechanism for the automatic correcting of the position of the telescope.

Palomar Mountain was chosen by Hale using information about the telescope capabilities of the area found by J.W. Hussey of the Lick Observatory. The building of the telescope was started in March 1934. A mountain road to the Palomar Observatory mountain site was built by workers of the Civilian Conservation Corps located in Doane Valley .

A 200 inch mirror disc made of Pyrex was cast in Corning, New York in 1934. It was the largest telescope ever built. 20 tons of glass were poured into a mold to make the largest glass casting and costliest scientific instrument ever made. It gave hope to many people of the depression. But there were technical difficulties at the end of the casting. A few months later a new glass mold was made. 

The gigantic mirror had to be moved from Corning, New York to the Caltech Optics Laboratory in Pasadena, California. It took four railroad companies to move the 17 feet high disc on three cars. The trains moved at a speed of 25 miles per hour during the day, but were stopped and placed under guard during the night.

The first telescope at the Palomar Observatory was the Schmidt camera in 1936. It found 100 supernovae and discovered the Shoemaker-Levy comet in 1993. A 60 inch telescope was built to take some of the load off of the Hale telescope in 1970. A 24 inch robotic telescope was built in 2006. From 2003 to 2008 the Palomar Planet Search Telescope searched for planets orbiting nearby stars.