Hale completed the Snow telescope in 1903, but quickly realized he had some problems: The quivering air currents, shifting as temperatures changed, blurred the images, and the Sun’s heat was warping the mirrors.
King of the hill
Hale thought he knew how to solve the visibility problem. He would move the telescope to a new location — a mountaintop, where the air would be thinner and the air temperature would change less often and less drastically. With some effort, he convinced Helen Snow to let him move the telescope to Mount Wilson in California. In 1904, mules helped drag the telescope and other building materials up the narrow, winding path to the top of the mountain.
The thinner air did lead to less blurriness, and the images improved. But the mirrors were still reacting badly to the heat. Hale decided to restrict viewing to morning and evening, shield the mirrors the rest of the time, and use fans and heaters to try to keep the mirror’s temperature steady.
Despite the effort involved, the Snow telescope taught astronomers much about the Sun. Mount Wilson now has two other solar telescopes. And Hale was so impressed with the viewing conditions on the mountain that he had many of his other telescopes built there as well.
