But a few auspicious encounters revised this vainglorious plan. Lick had once spent a few days with a visiting amateur astronomer and lecturer, George Madeira, who captivated him with talks about astronomy's latest discoveries. They met again a few years later for some telescope viewing when Madeira allegedly asserted, “If I had your wealth, Mr. Lick, I would construct the largest telescope possible to construct.” Around the same time Joseph Henry, then head of the National Academy of Sciences as well as the Smithsonian, was visiting San Francisco and arranged a meeting with Lick to discuss how wealthy men could use their money to cultivate science. The following year, 1872, the Harvard naturalist Louis Agassiz gave a widely reported lecture at the California Academy of Sciences, where Agassiz echoed Henry's refrain.
All these lessons struck a chord. Lick soon astonished the California Academy when he granted the institute, without prior notice, the gift of a downtown lot to build a museum and more expansive headquarters. Academy president George Davidson, a geodetic surveyor and astronomer, promptly called on Lick to thank him, initiating a friendship. When Lick was later felled by a stroke and confined to a two-room suite at his hotel for nearly a year, Davidson regularly visited, engaging Lick with chats about the rings of Saturn, the belts of Jupiter, and other astronomical topics. Lick soon abandoned his scheme to build a pyramid and decided instead to erect a telescope “superior to and more powerful than any telescope yet made,” right on his favored city spot, the corner of Fourth and Market.
An in-town telescope was never built (fortunately), largely due to Davidson's intervention. As both an amateur astronomer and a geodeist, a profession that took him to towering mountain sites, he had long been convinced that astronomy would best be served by taking its instruments to the highest elevations possible, where a telescope's resolution would improve immensely in the clear, more rarefied atmosphere. Isaac Newton first pointed this out in the eighteenth century. “For the Air through which we look upon the Stars, is in a perpetual Tremor,” he wrote in his Opticks. “… The only remedy is a most serene and quiet Air, such as may perhaps be found on the tops of the highest Mountains above the grosser Clouds.” And preferably in a region with a dry season, free of rain.
Over time Lick came to accept Davidson's compelling idea and in the fall of 1873 authorized the funds to construct a state-of-the-art observatory in the arid Sierra Nevada Mountain Range at an elevation of 10,000 feet. Caught up in the excitement of this novel venture, Lick pledged $1 million, a princely sum. No observatory had ever been established in such a remote and elevated locale. In that decisive shift, astronomy would soon change in a remarkable way, whisking the field away from its previous urban settings.
Over the next three years, Lick fiddled with the provisions of his trust, fired and hired assorted board trustees, reduced the price tag to a tightfisted $700,000, and changed his mind on the telescope's location. Once set for a spot near Lake Tahoe by the Nevada border, the site was eventually shifted to Mount Hamilton, a shorter peak (4,200 feet high) just to the east of San Jose, where Lick could look up and proudly view it from his property. Davidson, sorely disappointed by the lowered elevation and Lick's parsimonious ways, left the project and refused to speak to his former benefactor ever again.
Davidson's snub mattered little in the end, for Lick soon passed away. He died on October 1, 1876, at the age of eighty. Only then did construction of the mountaintop observatory, an arduous and unprecedented endeavor, truly get under way: Congress at last approved transfer of the public land, the local county built a road to the top, and the mountain peak was certified by an expert as exceptional for its atmospheric stability. Mount Hamilton's sharp, knife-edged profile causes minimal disturbance as air flows in from the west. Fulfilling Lick's decree, the largest refracting telescope in the world—one with lenses ten inches wider than the previous record holder at the U.S. Naval Observatory—was installed in a magnificent domed building, designed in the Italian Renaissance style and large enough to accommodate the scope's lengthy tube. Massive hydraulic cylinders allowed an astronomer to raise or lower the entire circular floor to keep him level with the telescopic eyepiece. The top thirty feet of the mountain had been blasted away to provide a level space for the rambling complex, which included housing, workshops, offices, and a library. The observatory operated as a small town, with families living on-site and supplies brought up daily by wagon from San Jose. A visitor dubbed it the “little Republic of Science.”
Lick became the new republic's patron saint, for his egotism never completely disappeared with his noble gift to astronomy, even after his death. In January 1887, as soon as the telescope base was complete, Lick's remains were brought up the mountain and reburied, his body resting directly under the grand instrument he funded, in the very base of the pier supporting the giant refractor. Tour groups still visit the tomb today. Davidson claimed credit (as did others) for the interment idea, first voiced when Lick was alive. He was surprised the old man agreed. At the time Davidson had suggested a cremation and burial of the ashes, to which the former carpenter quickly replied, “No sir! I intend to rot like a gentleman.”
The choice for director of the new Lick Observatory was Edward Holden, a graduate of West Point and an unaccomplished astronomer whose sole qualification seemed to be that his energy and initiative had once impressed Simon Newcomb, then America's most revered astronomer, while he was assisting Newcomb at the Naval Observatory. A proud and pompous man, Holden at least had a keen eye for talent. Aware of Keeler's outstanding work at Allegheny, Holden hired him in 1886 to get the new mountaintop observatory and its equipment up and running. Of all Holden's hires, James Keeler was by far the best trained. Bringing Keeler to the mountain was the best decision Holden ever made during his tumultuous directorship.
A Rather Remarkable Number of Nebulae
Keeler traveled to the Lick Observatory along a road that was a marvel of engineering in its day. Although Mount Hamilton is less than a mile high, the journey from its base to the top is more than twenty miles in length, with the roadway sinuously zigging and zagging as it gradually ascends. There are some 360 switchbacks in all, and some were even given special names, such as “the Tunnel,” “Crocodile Jaw,” and “Oh My Point,” branded by the oft-heard refrain as people sat atop the stagecoach and looked down in horror at the point's steep drop-off. The serpentine route was installed to maintain a gentle gradient, so that stagecoach horses in the nineteenth century never needed to break their stride.
Upon reaching the top, Keeler was immediately enamored of the breathtaking scenery. “The view from the observatory peak is a very beautiful one, particularly in the spring, when the surrounding hills are covered with bright green verdure, and the eye looks down upon acres of wild flowers,” he later wrote in a pamphlet for visitors. “To the west lies the lovely Santa Clara valley, shut in from the ocean by mountains somewhat lower than the Mt. Hamilton range. Sometimes the entire valley is filled with clouds, rolling onward under a clear sky and bright sun like a river of snow… The surrounding mountain tops project out of the fog like black islands.” Often the ocean fog arrives at sunset, rolling in from the Pacific at the Golden Gate, to the north, and Monterey Bay, to the south.
Not everyone on the mountain was enthusiastic about Keeler's arrival. The observatory's superintendent, Thomas Fraser, was initially wary of the newcomer. “If he has the right ring all will be right,” said Fraser, “but if Stubern [sic] then things will go wrong and he will have to leave that is all there is to it.” It didn't take long, though, for Fraser to be won over by the exceptional skill Keeler displayed as the telescope was being prepared for operation.
Its great lenses were finally installed on New Year's Eve 1887, but due to severe weather the staff could not test the telescope out until a few days later. Often in the wintertime, storms would sweep over the mountain with winds gusting more than 60 miles per hour, which would drift the snow about the dwellings more than ten feet high. Once the staff got back to th
e telescope, the trial run did not go well. To their horror the astronomers discovered that Alvan Clark, the telescope maker, had misstated the instrument's required length. Much like the Hubble Space Telescope's initial mishap a century later, they couldn't get it into focus. The telescope's tube should have extended fifty-six feet, but instead was six inches too long, forcing them to get out their tools and spend valuable days cutting the tube down to size. Clark's son, a partner in the telescope firm, was there for the trial, “a terrible old blow and grumbler,” Keeler told Holden. While Clark insisted that his firm's glass was superb and the eyepieces “triumphs of art,” he declared the dome “worthless.”
With its tube shortened, the telescope was at last tried out on January 7, 1888, a cloudless night that was piercingly cold. With the dome frozen solid that evening, the handful of staff members and guests present could only passively observe the objects that happened to pass by the dome's slit, open toward the southeast. Yet, “no inconvenience was felt beyond the necessity of a little waiting,” recalled Keeler. He was pleased to find the clock running smoothly and the mounting working well. The group first observed Rigel, a blue-white double star, followed by the Orion nebula, its great streamers making it one of the most spellbinding sights through a telescope. “Here the great light-gathering power of the object glass was strikingly apparent,” Keeler noted. Then, just after midnight, Saturn came into view. Keeler reported that the planet was “beyond doubt the greatest telescopic spectacle ever beheld by man. The giant planet, with its wonderful rings, its belts, its satellites, shone with a splendor and distinctness of detail never before equaled.” Everyone in the party took a look. Afterward Keeler spent some time studying Saturn more carefully, which led to Lick Observatory's first discovery. He spied a fine, dark line in Saturn's outer ring, “a mere spider's thread,” as he described it. It was a breach (now best known for historic reasons as the Encke Gap, after an early-nineteenth-century German astronomer) that had never before been clearly seen. A superb drawing Keeler made of Saturn, based on his sketch of the planet that night, was displayed at the 1893 Chicago World's Fair.
James Keeler
(Mary Lea Shane Archives of the Lick Observatory, University
Library, University of California-Santa Cruz)
Six feet tall with fair wavy hair, Keeler cut a fine figure. Despite his isolated upbringing in rural Florida, he became a keen judge of human nature and was often called upon to handle personnel and scientific crises at the observatory, which he carried out with the calm discretion of an international diplomat. “He was tolerant, amused and unwilling to take sides,” said Keeler's biographer Donald Osterbrock. “He always sought to put the best construction he could on anyone's activities, to emphasize the positive, and never to criticize unless absolutely necessary. It was perhaps not the most courageous philosophy in the world, but it [took] him far.”
And as an astronomer, Keeler was outstanding, studying a range of subjects from solar eclipses to planetary features. Photography was still in its infancy, so Keeler continued to make drawings that were praised by his colleagues as marvelous reproductions. “Beautiful and accurate,” reported fellow Lick astronomer Edward E. Barnard in a notice to the Royal Astronomical Society. “… [Keeler] has a real artistic ability such as very few observers possess.” Keeler's real forte, however, was in using a spectroscope, which was a relatively recent addition to astronomy's instrumental arsenal. The scientific basis for it was established in the seventeenth century.
A young Isaac Newton, sitting in a darkened room in 1666, let a small stream of sunlight enter through a hole in his window shutter. He then passed it through a triangular prism of glass. Beholding a rainbow of colors on the wall behind him, an enchanting phenomenon observed with pieces of glass since antiquity, Newton clearly demonstrated that white light was a mixture of many hues: On one end was a band of red, followed by orange, yellow, green, and blue, until it reached a deep violet on the other end. He dubbed this multicolored display a spectrum, a word previously used to denote an apparition or phantom. By the early nineteenth century Joseph von Fraunhofer, a master Bavarian optician, cleverly combined a slit, a prism, and a small telescope—what came to be called a spectroscope—to examine the spectrum of the Sun more closely. Peering through the eyepiece, he was surprised to discern hundreds of dark lines in the spectrum, as if a series of black threads had been sewn across a rainbow. They resembled the ubiquitous bar codes now found on consumer products. But unfortunately, Fraunhofer died before he could pursue the origin of those mysterious dark slashes.
Answers arrived from the creative experiments being conducted in chemistry laboratories. Even before Fraunhofer's spectral tests, chemists had noticed that metals or salts, when heated to incandescence, emit certain colors. Salts containing sodium, for example, burn an intense yellow-orange when heated by a hot flame. When looking at the heated material through a spectroscope, the chemists saw that its spectrum was composed of discrete lines of color, resembling a picket fence with colorful posts. Whereas the solar spectrum was a continuous rainbow riddled with dark lines, these laboratory spectra were the exact opposite: thin bright lines of colorful emissions set against a dark background.
By 1859 the physicist Gustav Kirchhoff and the chemist Robert Bunsen (creator of the legendary lab burner) at last revealed the meaning behind these bright and dark lines. With the clear hot flame of Bunsen's improved instrument, free of the deceptive contamination that plagued earlier researchers, the two German colleagues were able to conclusively prove that each chemical element produces a characteristic pattern of colored lines when heated and viewed through a spectroscope. The elements weren't emitting an entire rainbow but rather just a few select colors. More consequential, the patterns were as unique and distinguishing as a fingerprint. Each element on the periodic table had its own personal set of emissions. Using their spectroscope one evening to peer at a distant fire in the port city of Mannheim, visible across the Rhine plain from their laboratory window, Kirchhoff and Bunsen were thrilled to detect the spectral signatures of barium and strontium in the roaring blaze. It didn't take long for them to fathom that they could analyze the Sun and stars in a similar fashion, as light knows no distance in the voids of space. Light can be sent through a spectroscope whether it originates from a distance of one foot, ten miles, or a billion light-years away. Before this revelation, astronomers only knew that a star shines, that it occupies a certain position on the celestial sphere, and in some cases moves. But now they were acquiring the means to determine a star's composition and temperature, information once thought impossible to glean.
When an element is hot and glowing, it radiates its distinctive pattern of spectral colors. But at other times it can absorb those same wavelengths, which explains the origin of the dark lines that Fraunhofer found in the solar spectrum. Each element in the Sun's cooler outer atmosphere absorbs its designated colors, robbing the sunshine of those selected wavelengths before they arrive on Earth. The bright lines are simply the reverse of this process—the elements emitting those very same wavelengths of light as they fiercely burn. Either way—dark or bright—the pattern of lines indicates the presence of the element. Not until the early twentieth century, with the advent of atomic physics, did scientists come to understand this behavior as arising from the electrons in an atom jumping from one energy level to another, the atoms emitting bursts of light when they lose energy and gaining energy when they absorb the photons.
Astronomers quickly realized that, along with revealing a star's composition, a stellar spectrum could also tell them how the star was moving. In the 1840s the Austrian physicist Christian Doppler had surmised that the frequency of a wave, such as the tone of a sound wave or the color of a light wave, would be altered whenever the source of the wave moved. We've all heard the pitch of a siren rise to a higher tone as a police car or ambulance races toward us. This is the very effect that Doppler spoke of: The sound waves emitted by the screeching siren crowd together as
they approach us, shortening their length and likewise raising the pitch. Conversely, as the police car pulls away, the sound waves stretch out, producing a lower pitch. In an analogous fashion, a light wave's length is shortened (gets “bluer”) when the source of the light approaches and is lengthened (gets “redder”) when the source moves away.
Astronomers, though, don't assess the overall color of a star or galaxy to measure its speed. That would be too difficult. They can more easily examine how the bright and dark lines in a celestial spectrum shift from their well-known laboratory positions. Depending on the object's motion, the lines can shift toward either the blue or red end of the spectrum. If a star or nebula, for example, is headed for us, its spectral lines move over toward the blue—that is, the lines get “blueshifted.” If moving away, the lines swing over toward the red and hence become “red-shifted.” The exact velocity is pegged from the amount of shift in the spectral bands. Blueshifts and redshifts are nothing less than the speedometers of the universe.
Keeler had the eye of a hawk in measuring how the celestial light entering his spectroscope was separated into its component wavelengths, with each spectral line offering enticing clues. He was America's leading practitioner of this new technique, with some of his best work being done on measuring the speeds of nebulae within the Milky Way. In Latin, nebulae is the word for “clouds” or “mist,” exactly what these extended objects look like through a telescope. Some are roundish and were dubbed “planetary nebulae” in the eighteenth century by British astronomer William Herschel, who thought they resembled planets through his telescope. Today, astronomers know that such circular nebulae are the result of aging stars casting off their outer envelopes. Other nebulae, such as the renowned Orion nebula, are more irregular and diffuse, made luminous by the new stars being born within these great cosmic oceans of gas.
The Day We Found the Universe Page 3