Palomar (and Mount Wilson) Observatory: Hale, Refraction, and Reflection (Part 7)

To start at the beginning of our series on Palomar Observatory and the man called Hale, click HERE.

The supposed deathbed words of the German writer Johann Wolfgang von Goethe, author of Faust, were supposedly, “More light!” In German, Mehr Licht! For many, these final words have been a cry for inspiration and a reflection of Goethe’s lifelong fascination with light (Goethe also authored a natural science tract, Theory of Colours). A few quick Internet searches easily reveal that the story of Goethe’s final words is probably less about intellectual inspiration and more about a darkened bedroom.

George Ellery Hale
George Ellery Hale

That same cry—More light!—could also be seen as one of the driving impulses for the career of astronomer George Ellery Hale. Hale spent the middle part of the 1890s getting the Yerkes Observatory up and running. Before Yerkes and its world-record 40-inch refracting telescope were completed (the telescope gathered first light in the summer of 1897 and the observatory was dedicated that fall), Hale was already fully engaged in developed a larger telescope, one that would emphatically gather “More light!”

At the same time that Yerkes was being constructed, a technical debate was occurring in astronomy over whether refracting or reflecting telescopes were the field’s future tools. The fundamental difference between the two types of telescopes rests upon how they gather and focus light. Refracting telescopes use lenses. Reflecting telescopes use mirrors. Refracting telescopes suffer from what is known as chromatic aberration, wherein the lenses of the telescope are unable to bring all of the wavelengths of light into focus at the same spot. Though many scientists, inventors, and tinkerers were working in the same area, the mathematician Isaac Newton is generally credited with developing reflecting telescopes. In her biography of Hale, Explorer of the Universe, author Helen Wright says

In a reflector, the light is not weakened by passage through glass; after reflection from the silver surface, all the rays, independent of color, are united in a common focus. In other words, a reflector is completely achromatic; it can make use of all available light.

Ritchey Telescope
Ritchey Telescope

In 1896, Hale took delivery of a 60-inch mirror blank with which he intended to build a reflecting telescope at Yerkes. As was always the case with Hale, he intended the new telescope to be the world’s largest. The 60-inch mirror blank’s arrival—it had been poured at the venerable Saint-Gobain foundry in France and paid for by Hale’s father—coincided with the Yerkes’ arrival of optician George W. Ritchey.  Ritchey built his own 24-inch reflecting telescope at Yerkes. Ritchey and Hale would collaborate on a number of reflecting telescopes, and in early puttering around with Ritchey’s telescope, Hale convinced himself that for certain kinds of astronomy, particularly for producing photographs, reflecting telescopes were the future.

The 60-inch mirror sat in the observatory’s basement for a number of years as Hale worked with the University of Chicago’s president William Rainey Harper to find the funds to build the telescope at Yerkes. It was never to be, in large part because Hale had been taken with the clear air and dark night skies of California since his trip to the Lick Observatory. In 1903, the stars aligned, and Hale moved to California. Using a $10,000 grant from Carnegie Institution, Hale began work on would eventually become the Mount Wilson Solar Observatory.

Hale was an intellectually curious man, with pursuits that included architecture, urban planning, and even Italian poetry. As a young man, he had been fascinated by the stories of ascetics living in monasteries in the Levant. Hale had long wanted to put this fascination into practice by creating a monastery for astronomers. In her book, Wright says:

He had dreamed of building such a monastery, where the male astronomers could live while observing on the mountain. (He had not forgotten the difficulties at Yerkes, or his resolve made then that, if he should ever found another observatory, the astronomers and their families would not live on the observatory grounds.)

Our Copy? Or the monastery’s?

Hale got his wish on the top of Mount Wilson, and in one of those delicious moments of serendipity that we love so much at Lofty Ambitions, the copy of Wright’s book that we have been reading was actually once a part of the monastery library’s collection.

Like the Columbian Exposition fire that nearly destroyed the telescope mounting for the Yerkes 40-inch, Hale’s 60-inch telescope was also beset by outside forces. He’d contracted with a San Francisco ship builder, Union Iron works, to build the massive steel structures need to support and aim the 60-inch mirror. The Great 1906 San Francisco earthquake destroyed a part of the Union Iron works, but just as in the fire in Chicago, Hale’s machines were miraculously undamaged.

Eventually, in 1908, Hale completed the observatory and his 60-inch telescope on Mount Wilson. The new instrument would go on to profoundly change our understanding of the universe. Mount Wilson astronomer Harlow Shapley, whom we’ve written about before, used the telescope to redefine the size of the Milky Way galaxy.

Today, the 60-inch is largest telescope in the world that is available for use by the public. Ultimately, the Mount Wilson 60-inch telescope was exceeded by Hale’s next telescope. This Friday, December 13th, 2013, is the 105th anniversary of the telescope gathering first light. Hale would be proud of that event.

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