Palomar Mountain Observatory, Astronomical observatory in San Diego County, United States
Palomar Mountain Observatory is an astronomical research facility in San Diego County, sitting at 5,600 feet (1,712 meters) elevation in the Palomar Mountains. The complex includes several telescope domes and scientific buildings spread across a forested mountain plateau.
Construction began in 1936 following funding from the Rockefeller Foundation, and the California Institute of Technology opened the completed facility in 1949. The main telescope was the largest optical instrument of its kind worldwide until the mid-1970s.
The name Palomar comes from the Luiseño word for 'place of the pigeons,' referring to the wild birds that once nested in the mountain area. Today the site operates as an active research center where astronomers from multiple institutions analyze light from distant galaxies and stars.
The observatory sits at the end of a winding mountain road that may close in winter during snow or ice conditions. Visitors should bring warm clothing, as temperatures at this elevation remain cooler than in the valley even during summer months.
The main mirror of the Hale Telescope was cast from a special heat-resistant glass that took almost a year to cool after pouring. The finished mirror element weighs about 14.5 tons and was transported by rail across the United States to the mountain.
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