The Day We Found the Universe (32 page)

Observations with the 100-inch did not really get going until the war was over and necessary personnel had finally returned from their military duties. Its first images—of the Moon, of nebulae—surpassed the promises that Hale had made to Hooker years earlier when a telescope of such a tremendous size was only a far-off aspiration. “In such an embarrassment of riches the chief difficulty is to withstand the temptation toward scattering of effort, and to form an observing programme directed toward the solution of crucial problems rather than the accumulation of vast stores of miscellaneous data,” said Hale.

High on Hale's list of priorities was determining once and for all the true size and nature of the universe, a job that Hubble took on with single-minded devotion.

Hubble's first night of observing on the mountain was on October 18, 1919. It took about an hour then to make the journey in a motorcar. Via the single stretch of telephone wire that ran to the top of Mount Wilson, the tollhouse keeper at the bottom alerted the observatory that a car was on its way, as the road was only wide enough for one car. Away from active observing for more than two years due to the war, Hubble initially freshened up his telescopic skills that autumn evening by using a 10-inch refractor called the Cooke lens. Though small, the telescope's wide-angle view enabled him to explore the sky quite handily. He took photos of the North America nebula (a diffuse cloud in the Cygnus constellation) and then directed the telescope to a nebulous loop of gas near the “belt” of Orion. He was getting back his sea legs, perusing familiar celestial territory, and mulling over his observing strategy for the coming months.

Seven days later Hubble tried out the 60-inch telescope. He took a photograph of the nebula NGC 1333, a rich star-forming region in Perseus, and later checked out how his beloved variable nebula, the one he first noticed as a graduate student at Yerkes, was doing. He noted that “striking changes have happened [in it] since 1916,” which was the last time he had taken a look.

Milton Humason, who became Hubble's devoted observing partner a decade later, first met the young astronomer during these opening runs at the observatory. “He was photographing at the Newtonian focus of the 60-inch, standing while he did his guiding,” recalled Humason, many years later. “His tall, vigorous figure, pipe in mouth, was clearly outlined against the sky. A brisk wind whipped his military trench coat around his body and occasionally blew sparks from his pipe into the darkness of the dome. ‘Seeing’ that night was rated extremely poor on our Mount Wilson scale, but when Hubble came back from developing his plate in the dark room he was jubilant. ‘If this is a sample of poor seeing conditions,’ he said, ‘I shall always be able to get usable photographs with the Mount Wilson instruments.’…He was sure of himself—of what he wanted to do, and of how to do it.”

Hubble got his first crack at the 100-inch telescope, what he called his “magic mirror,” on Christmas Eve. So immense was its light-gathering power that it could spot a candle from five thousand miles away. Hubble couldn't have asked for a more fitting holiday present; the atmosphere was almost at its best at the start of the evening, and it was also dark-sky time, a waxing crescent Moon having just set in the west. That was the prime opportunity to seek out the sky's faintest objects. He first photographed a hazy star near the Pleiades cluster. With a sixty-minute exposure, its nebulosity showed up fairly well. Afterward, he perused two more objects, a wispy planetary nebula and (again) his variable nebula NGC 2261. After Hubble aimed the giant scope at this target, he was able to obtain his best photo of the night. The variable nebula soon became his observational “mascot.”

At the end of his observing runs, if he was particularly eager to see his results, Hubble would go right to the dark room and develop his plates. Once dry, each was entered into his official Observing Book and put away in a numbered envelope. For marking his plates, Hubble used a special code: H 31 H, for example, stood for the hundred-inch telescope, plate number 31, taken by Hubble.

One of Hubble's first tasks on Mount Wilson was working with Frederick Seares to determine the color of “nebulous stars,” stars surrounded by diffuse clouds of luminous matter, such as the ones in the Pleiades. For that project he primarily worked with the 60-inch and got a paper published fairly quickly in the
Astrophysical Journal
. It was a warm-up session for Hubble's main purpose for being at Mount Wilson. He was going to finish what he started in his doctoral dissertation—figure out exactly what those faint spiral nebulae truly were. As he later told Slipher, he was committed to one issue and one issue only: “to determine the relation of nebulae to the universe.”

Henry Norris Russell was getting nervous about the spirals around this time. There were so many conflicting observations. The novae occasionally discovered within the spiraling clouds suggested they were far-off stellar systems. But then van Maanen was seeing them rotate, at an impossible rate if they were truly distant. “We are on the brink of a big discovery—or maybe a big paradox, until someone gets the right clue,” ventured Russell.

The dawn of the 1920s seemed the right time to break the impasse. With the war over, pent-up energies were fueling a plethora of inventions and clever ideas. Heber Curtis, now settled at the Allegheny Observatory, was particularly enamored of a newfangled entertainment medium. “I have just gone into the lecture room, pressed a button, and heard records by Galli-Curci and Rachmaninoff sent out by wireless telephony from East Pittsburgh, ten or twelve miles away,” he wrote his former Lick boss, Campbell. “As soon as the Westinghouse people start a broadcasting station at San Francisco, the mountain would enjoy one of these receiving and amplifying sets. They send out music, stock market reports, news bulletins, speeches, etc… We have one of their experimental models here on loan (hope they will eventually give it to us). It is called ‘the Aeriola Grand’; is the size of a small phonograph such as you have; is simplicity itself; has only one button and one dial,—no adjustments; about 75 feet of a single wire forms our aerial. Sermons on Sunday, with no collection possible!”

At Mount Wilson Albert A. Michelson and Francis Pease mounted a special instrument called an interferometer on the front of the 100-inch telescope and made the first successful measurement of a star's diameter. Betelgeuse, in the constellation Orion, was their target. They learned that if the red giant star on Orion's right shoulder were placed inside our solar system, it would engulf the planets out to Jupiter. And, of course, Harlow Shapley at this time was also on the mountain resizing the Milky Way.

Hubble's and Shapley's employment at Mount Wilson overlapped for about a year and a half, until Shapley moved to Harvard. Their relationship over that brief period, though, could hardly be called collegial. Both were from the heartland of America, but they might as well have been born continents apart. Hubble cultivated an air of sophistication and restraint around his colleagues. The cold and standoffish persona of his youth never went away. Hubble kept his distance and maintained a regal air. With his ever-present pipe, he would occasionally blow smoke rings out into the room or flip his lighted match and catch it, still alight, as it came down. As other astronomers put it, he was a “stuffed shirt,” who couldn't “write an inter-office memo without it sounding like the Preamble to the Constitution.” Shapley, on the other hand, retained his brassy and chummy country ways. Hubble's affectation for wearing jodhpurs, leather puttees, and a beret while observing or going around and saying “Bah Jove” was simply too much for Shapley to bear. An unadorned “Missourian tongue” was good enough for him. The fact that Shapley was a close friend of Adriaan van Maanen's made it even more difficult for the two midwesterners to cozy up. “Hubble disliked van Maanen from the time he himself arrived on Mount Wilson; he scorned him,” claimed Shapley years later. It may have been because van Maanen, more senior than Hubble, openly displayed his jealousy at having to share time on the 100-inch. To Shapley, though, “Hubble just didn't like people. He didn't associate with them, didn't care to work with them.”

Edwin Hubble wearing his knickers on Mount Wilson
(Courtesy of the Archives, California Institute of Technology)

Part of the coolness and tension between Hubble and Shapley had to do with their differing experiences during the war. Hubble had immediately volunteered, putting his professional life on hold and taking the risk that his research would be taken up by others. Shapley, who hated war, remained at Mount Wilson—the “conscientious slacker”—weakly suggesting that Hale convinced him to stay and taking on work that Hubble had hoped to tackle, such as the globular clusters. But, fortunately for Hubble, analyzing the mysterious nebulae was still a wide-open field when he returned from overseas. And once Shapley left for Harvard, Hubble at last had the chance to step out of the formidable shadow Shapley, then the golden boy of astronomy, had been casting on Mount Wilson.

Hubble first carried out an extensive study of the diffuse nebulae within the Milky Way, identifying the various types and describing the sources of their luminosity. But he also kept track of the “nongalactic nebulae” that he came across as he carried out this research. Hubble's sympathies certainly leaned toward the island-universe theory. When he was a graduate student at Yerkes he especially noted that the high velocities of the spiral nebulae “lend some color to the hypothesis that the spirals are stellar systems at distances to be measured often in millions of lightyears.” But he became more circumspect once he became a staff member at Mount Wilson, at least in print. Caution became his byword. He emphasized in a 1922
Astrophysical Journal
paper that the term
nongalactic
didn't mean the spirals were necessarily “outside our galaxy” but that these nebulae tended to avoid the galactic plane. At this point, Hubble's publications no longer contained grand references to island universes or other galaxies, as those of Heber Curtis and Vesto Slipher were doing. Hubble started to keep his words fairly neutral, adopting the guarded language that came to be a trademark of his research reporting. He was now consciously hiding his biases to avoid criticism.

Hubble was far more vocal and forthright, though, about his observational plans. In February 1922 he sent a lengthy, typewritten letter to Slipher, a member of the Committee on Nebulae for the International Astronomical Union, on his long-term strategy for studying the nebulae. It was going to be an all-out attack. Hubble planned to determine their structure, peg their distribution across the heavens, and measure their dimensions. And as a stealth advocate of the island-universe theory, Hubble wanted to obtain undeniable proof that stars—vast collections of stars—resided in the spiral nebulae. He knew that finding novae were crucial in doing this and urged the IAU that “half a dozen of the largest spirals in addition to Andromeda should be followed carefully for novae.” Major Hubble was now applying his lessons on military tactics to conquering his astronomical targets.

“I must confess that I am rather dazed by [Hubble's] letter,” said Lick astronomer William H. Wright, who had also received a copy of Hubble's agenda. “One can see that the nebulae will have no private life when he has his way. Hubble is a great lad, and I only hope that he will have the strength and energy to carry out a fraction of the work he would like to see done.”

Hubble, who had just gained a seat on the committee, was particularly fired up about a nebula classification scheme he wanted the IAU to adopt. To Hubble, properly categorizing the nebulae was an essential first step in determining their physical nature. By 1923 he had divided the nongalactic nebulae into two categories: the ellipticals and the spirals. An elliptical was an amorphous blob shaped somewhat like an egg. The spirals, of course, were the stunning pinwheels. If the bright center of the spiraling disk was a round bulge, he called it a “normal spiral;” if elongated, a “barred spiral.” The nongalactic nebulae that didn't fit either class, like those resembling the chaotic Magellanic Clouds, were tagged “irregulars.” But the IAU committee dragged its feet on Hubble's naming system and desired some changes, a rebuke that may have had long-term effects. At one point in the long wait, Knut Lundmark published a similar scheme, which enraged Hubble. He accused the Swedish astronomer of plagiarism. Afterward, Hubble was never keen to work on committees, attend general astronomy meetings, or share in collaborations. With a few exceptions, he tended to work alone. There might have been another reason for this as well. Though displaying a commanding public presence, Hubble was actually “pathologically shy around colleagues with whom he had little… contact,” contends Allan Sandage, who knew Hubble in his later years. Hubble proceeded to classify the nebulae in his own way and over time his arrangement was eventually accepted by the astronomical community.

Throughout 1923, over a total of forty-seven nights on the mountain, Hubble used both the 60-inch and 100-inch telescopes to survey a variety of nebulae around the celestial sky. He was on a reconnaissance mission. Though scarcely any nebulae were repeated, he did pay special attention to NGC 6822, a nebula in Sagittarius first discovered in 1884 by his former Yerkes colleague E. E. Barnard. The nebula stood out from the pack because it looked strikingly similar to the Magellanic Clouds in the southern celestial hemisphere.