George Hale: To Know the Stars and Sunbeams

Step by step, inch by inch, sometimes by luck, and often against great adversity, the human race has waded into the cosmos. 

Our collective adventure into the heavens—like a pioneering journey across a vast virgin ocean—is fraught with questions: How big is the universe? How many stars are there? Why do some “stars” seem to move away and some towards us? Why do some stars change how bright they are? How did they come to be? And, more ominously, will there be an end?

Despite centuries of looking up and asking, our questions continue. The key to finding answers has, so far, lain in the combination of man and machine. Having the right tools in the right hands makes it possible to check the questions off the list. But somehow the list never gets any shorter. The last century was an extraordinary time of cosmic exploration. In 1900, for instance, the Milky Way was the universe. But as the telescopes grew, so did everything else. Today we see even our galaxy as just a small stitch in the ever-expanding fabric of space and time.

George Hale’s contribution to our change in perspective was in building tools that have given us greater access to the universe. In an effort we may not ever see again from one man, he built the world’s largest telescope not just once, but four times. Then, placing his creations in the right hands, through his foundational work others were able to discover a new universe: larger and more complex than anyone had ever suspected. The great astronomers of the 20th century, Edwin Hubble, Harlow Shapley, Vesto Slipher, and Walter Baade made their observations at his instruments.

While the exploration continues (using even newer tools including space-based telescopes such as Hubble and the soon-to-be-launched James Webb Space Telescope, as well as other ground-based multi-mirror behemoths), it was Hale’s persistent curiosity and engineering talent that ignited the fires that have brought modern astronomy and cosmology up to warp speed.

Looking Up 

Born to William and Mary Hale during the summer of 1868, George was the oldest of three surviving children (two older siblings died in infancy). William Hale owned a successful Chicago business that manufactured and installed elevators. After the great fire of 1871, much of the Windy City was rebuilt and new high-rise constructions boosted the Hale elevator business.

George grew up in this time of reconstruction, new opportunity and new technology. His father understood the value of a good education and was generous with both his time and money, but—ever the businessman—expected some return for his outlay. Encouraged by his attentive parents, George, a sickly child who suffered from a variety of ailments, became very serious and driven preferring scientific instruments over toys. For instance, on a trip to London, George spent his allowance on an expensive spectroscope; his traveling buddy spent his on magic tricks.

Biographer Helen Wright notes young George’s character in regard to his serious nature:

Impelled by an insatiable curiosity, and stirred by the ‘divine discontent’ that would run through his entire life, his plans became bigger, his dreams of finer instruments for studying the natural world became greater.

To his father and mother, he scarcely seemed to have begun one project before another was on the way. ‘George always wanted things yesterday,’ his father said. And George Hale himself later acknowledged, ‘I was impatient to make rapid progress.’ While in time he learned to temper his impatience, these traits remained two of his outstanding characteristics. From his mother he had inherited a high-strung, nervous temperament, and often, as she watched him, she feared that, with his intensity and precocity, he would burn himself out early. Yet she soon learned that once he had set his heart on a particular object, there was little anyone could do to change it” (Explorer of the Universe).

These were general traits that served him well, but there is often a key moment in life that focuses one’s attention. In Hale’s case, it was his father’s gift of a small telescope, which was then mounted on the roof of their house. Although Hale enjoyed his view of the moon and planets, his defining moment came when he attached a homemade spectroscope to his little telescope. He saw then for the first time the spectrum of our nearest star, the sun. Of that moment Wright records Hale as saying, “[I was] completely carried off my feet. From that moment my fate was sealed.”

While most people prefer to simply look at the magnified image from the telescope, Hale was intrigued by the colored bands and their mysterious dark spectral gaps created by the spectroscope; his mind teased him with endless questions. These rainbow-like features result when sunlight is passed through a prism or diffraction grating attached where the eyepiece would normally be. In these lines Hale could look at the chemical makeup of the sun. In making this connection between how tools and physics reveal the nature of objects untouchable, Hale found his future: applying physical sciences to astronomical objects. He was 13 years old.

Before he graduated from the Massachusetts Institute of Technology in 1892, he had invented a new scientific instrument—the spectroheliograph: its purpose was to photograph the sun’s spectroscopic structure in minute detail. Now he just needed the right telescope to attach it to.

Kenwood Observatory 

After college, Hale built his own observatory at the family home in Chicago. Calling it Kenwood Observatory for the suburb they lived in, Hale moved up from his earlier 4-inch refracting telescope to a 12-inch reflector. There are two main types of telescopes: refractors, where the starlight passes through a lens at the end of the telescope, and reflectors, where the light reflects off a large mirror at the base of the telescope. Galileo’s first telescope was a refractor; Isaac Newton’s a reflector. All modern large telescopes are mirror-using reflectors; most of these use many smaller computer-controlled mirrors to make up one large reflecting surface.

Thus, in the microcosm of his own back yard, George Hale began down the path that he would follow across the country and for the rest of his life: building larger and larger telescopes.

Because larger telescopes catch more light, their images are not only brighter, they also contain more information. This is because a factor called resolution also increases with size. That is to say, larger instruments can show more detail much as a camera with a higher megapixel count can capture more image information. It was this increased resolution that Hale was looking for when he began his first studies of the sun.

His new spectroheliograph required both light and resolution. This was something that the telescope in his private childhood observatory could no longer provide. The upgrade to the 12-inch telescope allowed Hale to reach further into the sun’s spectrum and thus reveal more of its composition, but there was always more to see. Hale well understood the advantages of larger telescopes. To put it simply, they answered more questions. Hale’s unquenchable thirst for more and more physical facts about the cosmos drove him toward larger instruments. Like the spectroheliograph, if they did not yet exist, he would get them built.

Yerkes Observatory 

In 1892 Hale learned of two 40-inch lens blanks that had been cast, but not configured into shape. The telescope they were destined for had run out of funding. Combining his thirst for cosmic answers and his well-to-do connections, Hale was able to gather the funds to construct the first of his “world’s largest telescopes,” thus succeeding where those before him had floundered. His next task was to put all the elements together. Because the glass blanks had already been poured, George “simply” needed to polish the blanks, build a telescope to carry them, design and build a mount to hold the telescope skyward and track the stars, and create a building to keep the weather off them.

Although the lens-maker informed Hale it would take almost three years to grind the glass blanks into the world’s largest lens, he wasted no time in starting the planning from the ground up. This was not to be like most other observatories of the day, which were not built to be stand-alone institutions.

The largest telescope before the 40-inch Yerkes was the 36-inch Lick refractor, located on the 4200-foot peak of Mount Hamilton in the Diablo Ranges south of San Francisco. It was housed in a classic dome and was the first observatory built on a mountain top. The facilities at this time consisted of the dome housing the telescope and housing for the staff. Very little in the way of workshops were included on the observatory grounds.

Hale’s plan was taken from his teenage years at his home observatory. He wanted to build not just a new telescope, but also a better way of doing astronomy—a facility that could support many people working in different roles on the same site to add value to the science collected by the telescope. The facility would include machine shops and optics rooms where the astronomers themselves could assemble new instruments to investigate whatever particular questions came to mind.

This concept of an entire observatory as a physical laboratory was revolutionary,” notes Wright. “In contrast, the original plan for the Lick Observatory, completed in 1889, had no provision for a darkroom or for a spectroscopic laboratory.”

Located in Williams Bay, Wisconsin, the resulting Yerkes 40-inch refractor, a long, cannon-like affair, looked more akin to something to shoot the moon rather than gather in light. Nevertheless, to this day, the Yerkes remains the world’s largest refracting telescope, and the observatory workshops are still used for construction of state-of-the-art instruments for other telescopes.

This new type of observatory, the first of the four, really did come together smoothly under Hale’s direction. Perhaps the only glitch was that the complicated observatory floor—designed to be raised and lowered to allow the astronomer easy access to the eyepiece, totally collapsed just before the observatory opened for regular use. Of course, it was successfully rebuilt.

In 1895 Hale originated another institution that is still in place today: the Astrophysical Journal. This important publication brought the world’s best minds together in one place to share their collective knowledge of the physical sciences of astronomical objects. To this day, the Astrophysical Journal is still printed three times a month.

Coming West 

In 1902 Andrew Carnegie made a grant of 10 million dollars to establish an institution to further scientific research. Hale made an appeal for a portion of the funds to be used for a new observatory with a large reflector telescope for stellar observations as well as a solar observatory. Although it soon became clear that his plans would not be funded immediately, Hale, with typical courage and hope, set off with his family to settle for a time in California. He had long heard of the clear skies and good weather in Southern California. 

Arriving in Pasadena, his plan to establish a solar observatory gradually lifted his gaze to the summit of Mount Wilson overlooking the Los Angeles basin. There he hoped to gather the necessary data to convince the Carnegie Institution that his plan was sound. Due to a unique mix of geographical features, Mount Wilson had some of the steadiest skies in the United States. Steady seeing, as it is called, is greatly sought—even coveted—by astronomers; such locations offer a good mix of high altitude and a laminar or smooth flow of air that keeps the starlight from dancing around on its way through the atmosphere to the telescope. The result is a sharper, less distorted image. It was this sharp image that Hale was seeking to increase the information that he could tease out of the sun’s spectrum. 

In the meantime, he also became instrumental in establishing Southern California as a scientific hotbed through his participation in the founding of the California Institute of Technology. Hale’s influence is still seen but often overlooked even in the design of city buildings such as Pasadena’s domed City Hall. He also persuaded Henry E. Huntington to endow the Huntington Library and Art Gallery. The Huntington Library remains an important landmark and historical institution. Edwin Hubble’s papers, for instance, are housed therein. 

Back on the mountain top, Hale was very active both mentally and physically in the building of the Mount Wilson solar observatory. Working with his assistant George D. Jones during the winter of 1903, it was not uncommon for Hale to walk the two-feet-wide, nine-mile-long path down from the mountain, ride a bicycle from the base into Pasadena, pick up the needed supplies and then return carrying them on his back. In April 1904, he headed down the mountain with new solar photographs and a train ticket for Washington D.C. to attend the meeting of the National Academy of Sciences. 

Hale parlayed his photos into a $10,000 Carnegie grant and garnered permission to relocate the solar telescope from Yerkes to complete the Mt. Wilson project. The following few months were hard work, but he reveled in the isolation of the mountain; the pioneering spirit of the small group of astronomers that gathered on the summit enlivened the exhausting work. 

With the solar telescope in use almost every day, Hale became unhappy with the fact that good results could only be obtained the first few hours of each morning. After that, the sun’s heat on the ground would cause the light to shimmy and distort the images. This led Hale to conceive the solar tower. A mirror on the top of a tower would reflect the sun’s rays down a vertical tube. Because the mirror is high up, the heating of the ground did not affect the light. Hale also found that the vertical light tube was less affected by turbulence than a horizontal one. The first solar tower, some 60 feet in height, was built in 1908. The improvement in results, even in the middle of the day, meant that this new telescope became the instrument of choice for the researchers on the summit of Mount Wilson.

Hale had been fascinated in sun spots since viewing them from his small rooftop observatory as a teenager. Now, with the increased stability and resolution of the solar tower, he was able to put many of his different studies together and, in June of 1908, prove a most important discovery. The sun had a magnetic field. 

But Hale, always straining to gather more data from the heavens, needed still more light. With the lessons learned from building the 40-inch Yerkes telescope fresh in his mind, he turned to building a large reflecting telescope. George Hale would soon be the driving force behind the next “world’s largest telescope,” to be pressed into service on the summit of Mount Wilson.