March 26, 1936: Successfully built the world's largest telescope

In 1936, the world's first 5m diameter glass lens was successfully built and shipped by train from Corning, New York to California for Hale telescope installation. Palomar close.

In the early twentieth century, the idea of ​​creating a 200-inch reflecting telescope was made by American astronomer George Ellery Hale in April 1928.

The project was funded by the Rockefeller Foundation for a total of $ 6 million (at the time of the time); including fabrication of glass, observatory and auxiliary equipment. The observatory is built at Mount Paloma, used by the California Institute of Technology.

According to the original design, the spherical mirror placed in the telescope is made of pure quartz material. However, at that time, manufacturing had cost nearly US $ 1 million but still could not produce a large enough quartz mirror. Therefore, George Ellery Hale had to come up with an agreement with Corning in New York to create a mirror from a new glass mixture of Pyrex .

Manufacturing began in December 1934. 20 tons of molten Pyrex glass at temperatures close to 1,500 degrees C are poured into the mold. After that, it was left for nearly a year to lower the temperature.

This lens weighs up to 20 tons, is capable of resisting deformation by temperature impact.

It took 4 years to shape and polish, then placed in an incubator and cooled gradually over a period of 1 year. The transport of this lens is also difficult, trains are only allowed to run at a speed of 40km / h in a special anti-collision device.