Telescopes from the Ground Up

A second look

Hale, defeated at every turn, went back to the first glass disk. The bubbles might not be close enough to the surface to affect it, he decided. Hale had the glass tested, and his researcher reported back that the bubbles might actually strengthen the glass.

Hale turned the disk over to telescope-maker and astronomer George W. Ritchey. Ritchey and his team, working in the same carefully controlled environment they relied on for the 60-inch telescope, took 5 years to turn the glass disk into a mirror.

Record setter

Get to the root of it

And what a mirror it was! Once it was installed, the entire telescope weighed 100 tons. The telescope could be adjusted, like the 60-inch, for both photography and spectroscopy. All motions of the telescope and its dome and shutters were electrically controlled by 30 motors. One of the drawbacks, however, of such a large mirror was that it took so long to adjust to observatory temperature. The changing temperature would make the glass expand and contract, causing the mirror to change shape and lose focus and image quality, which meant observations were difficult until it had settled down.

When it was completed in 1918, the telescope became the biggest in the world, a position that had been held for 75 years by Lord Rosse’s Leviathan.

The Hooker telescope, with the superior light-gathering power of its massive mirror, would reveal the true vastness of the universe for the first time.

Click here to see all avaliable eras.
Huge Reflectors


Image of Edwin Hubble examining a photographic plate.
Edwin Hubble
Using the Hooker telescope, Edwin Hubble discovered that "spiral nebulae" are galaxies outside the Milky Way.
Read about him