Hale Telescope

The Hale Telescope inside its dome at Palomar Observatory in Southern California, its open tube carried on a massive steel equatorial mount. At the bottom of that tube sits a 200-inch (5.1-meter) mirror, a Pyrex disk weighing 14.5 tons, cast after an earlier plan for a quartz mirror was dropped. Dedicated on June 3, 1948, before it was quite finished, it remained the largest effective telescope in the world until 1993, a 45-year run at the top.