Hale Telescope, Reflecting telescope at Palomar Observatory, San Diego County, California, United States
The Hale Telescope is a reflecting telescope at Palomar Mountain Observatory in California, featuring a 200-inch (5.1-meter) primary mirror made of borosilicate glass. The movable structure weighs 500 tons and rests on hydrostatic bearings that allow precise tracking motions.
George Ellery Hale secured a $6 million Rockefeller Foundation grant in 1928, and construction of the observatory and dome began in 1936. The 200-inch Pyrex mirror was cast at Corning Glass Works in 1934, after a first pour failed when mold blocks broke loose. World War II interrupted work, and the telescope was dedicated in 1948, seeing first light on January 26, 1949, under Edwin Hubble.
The name honors astronomer George Ellery Hale, who spent his career building large telescopes and started this project. Observers worked inside a capsule in the beam path to measure starlight without extra mirror losses.
A small motor of only one-twelfth horsepower moves the entire structure, enabling precise alignments needed for astronomical observations. The dome offers guided tours where visitors can see the telescope up close without disturbing measurement programs.
The facility identified quasars for the first time through spectral analysis, expanding understanding of distant cosmic objects. Researchers could position themselves at prime focus inside a capsule to measure directly without extra optical elements.
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