ヘール望遠鏡
By 1905, the largest telescope in the World was the Harvard 60-inch Reflector ( 1.524 m 60″) at Harvard College Observatory, USA. Then in 1908, Mount Wilson Observatory matched that size with a 60-inch reflector of their own, and throughout the 20th century, increasingly larger reflectors would be established, aided also by refinements to mirror technology vapor-deposited aluminum on low-thermal expansion glass, pioneered for the 200 inch (5 meter) Hale telescope of 1948.