02/26/2025
A 1930s photo of physicist and engineer George V. McCauley inspecting the interior of the 200-inch mirror for the Hale Telescope.
Given the challenge of making a solid glass mirror of such immense size, Corning Glass Works' engineers devised an innovative honeycomb core structure to reduce weight while preserving strength.
They also selected Pyrex glass for its minimal thermal expansion, ensuring the mirror’s optical precision remained uncompromised.
After an initial casting failure in March 1934, McCauley’s team perfected the process, successfully recasting in December 1934 and allowing the mirror to cool over ten months before undertaking an extensive 11-year grinding and polishing process.
Installed at the Palomar Observatory in 1948, the Hale Telescope became the largest and most powerful optical telescope of its time. Its 200-inch mirror enabled astronomers to explore distant galaxies, nebulae, and quasars, leading to significant discoveries about the universe’s structure and expansion.
