The Glass Universe

by Dava Sobel

  The transfer and enlargement of southern operations looked to be the observatory’s most outstanding material achievement in thirty years. Overseeing the project from afar sapped Shapley’s energy, but did not derail his other activities. Together with Miss Sawyer, the current Pickering Fellow, he was developing a classification scheme for the hundred-odd globular clusters encircling the Milky Way. With Miss Ames, he was looking beyond the clusters to the more distant spirals, now recognized as external galaxies, or “island universes” outside the Milky Way, and taking a census of them. Shapley was also hosting foreign visitors attracted to Harvard by the cache of glass plates: one moment he was saying good-bye to Ejnar Hertzsprung, who spent seven months in residence between 1926 and 1927, and in the next moment welcoming the new guest researcher, Boris Gerasimovič from Russia. Simultaneously, as the observatory’s spokesman and chief fund-raiser, Shapley kept up a heavy schedule of public talks and also a series of popular radio broadcasts, which he was collating and editing for publication—all while writing his own Harvard Monograph about star clusters.

  The director’s obvious exhaustion made George Agassiz uneasy. “You are that enviable and rara avis, the right man in the right place,” Agassiz reminded Shapley on May 20, 1927. “Don’t injure your machinery by running it at too high speed. The traveler who keeps well within his reserve power will make a longer and more fruitful journey than he who tries to crowd into each day more than it will hold. Delegate your authority, or if that is not possible, cut down the product. Don’t burn yourself out, you are too valuable a man.” Shapley promised he would arrange a family vacation toward summer’s end.

  In July the Parases reached South Africa’s Orange Free State and sited the new permanent facility fourteen miles northeast of Bloemfontein, at Maselspoort. The altitude of the low hill, or kopje, where they settled was 4,500 feet, only about half the height of an Andes peak. But the seeing, which was everything, was better than at Arequipa. The Boyden Station born on “Mount Harvard” now commanded the view over “Harvard Kopje.” The city of Bloemfontein, opening its arms to the new scientific center, extended water pipes to Maselspoort at government expense, along with power and telephone lines. Within a few weeks the Parases were able to resume their sky patrol of the southern latitudes.

  Summarizing the highlights of the year in his September report to President Lowell, Shapley outlined more than forty projects in progress, without trying to describe the research in non-astronomer’s terms. He declined to list the previous twelve months’ worth of observatory publications by title and author, as had been the practice in past reports, on the grounds that there were too many of them; a full bibliography would take up too much space. Shortly after he submitted the report, the director and first lady of the observatory announced the birth of their fifth child, Carl Betz Shapley, on October 11, 1927.

  In November Lydia Hinchman, beneficent founder of the Nantucket Maria Mitchell Association, endowed yet another special fellowship for women at the Harvard Observatory. “This gift comes just at the right time,” Shapley said in his note of thanks. “The day before its arrival Miss Helen Sawyer, one of the Radcliffe graduate students at the observatory, talked over with me the possibility of going on in her study for a doctor’s degree in astronomy.” Miss Sawyer, who had entered Mount Holyoke as a chemistry major, switched to astronomy in her junior year under the influence of Professor Anne Sewell Young. One event in particular had swayed her: “For the total solar eclipse of January 24, 1925, Miss Young was able to get a special train to take all the college people to a golf links in Connecticut, inside the path of totality. There the glory of the spectacle seems to have tied me to astronomy for life, despite my horribly cold feet as we stood almost knee deep in snow.”

  While still at Mount Holyoke, Miss Sawyer had developed “a particular fondness for globular clusters as my favorite celestial objects.” At Harvard she worked with the world’s authority on these objects, even entering her observations in the same record book that Shapley used. Miss Sawyer was also pleased to meet Solon Bailey, the clusters’ first champion, and to immerse herself in the very plates he had taken with the Bruce telescope in Peru. Using these and other images, she helped Shapley divide the stellar conglomerations into several subclasses according to the concentration of stars at their centers. The differences hinted at various evolutionary stages of cluster development. Under Shapley’s guidance Miss Sawyer also redetermined the apparent photographic magnitudes of all the clusters, in an effort to confirm the distance of each.

  Miss Sawyer was poised to receive her master’s degree from Radcliffe in June 1928, when Mr. Hogg would be granted his from Harvard. Together they looked forward to still higher academic distinction, and to much else besides. Frank thought he could complete the doctoral degree requirements in just one more year, but Helen needed at least another two, possibly three. Radcliffe insisted that she master the German language, and Mount Holyoke had given her insufficient grounding in mathematics and atomic physics. Indeed, when she attended her first Harvard colloquium to hear Miss Payne speak “On the Lifetime of an Excited Hydrogen Atom,” she innocently mistook the title of the talk for an attempt at humor.

  • • •

  MISS PAYNE MADE THE TRANSITION from postdoctoral fellow to full-fledged astronomer in 1927, drawing a salary from the observatory of $175 a month. As part of her new duties, she took over the editing of all in-house publications—annals, bulletins, circulars, and monographs. She edited with relish, professing a real love for “the hurly-burly of the University Printing Office, the look and smell of the fresh galleys, the detail of proofreading, the craftsmanship of makeup.” She also drew diagrams for the other authors, and, in the case of foreign authors, rewrote their papers to improve their English if necessary.

  Although not a professor, Miss Payne instructed the graduate students and supervised Frank Hogg’s doctoral research. Shapley thought she deserved an academic position, and said so to President Lowell, who opposed the idea. Just as Lowell had once denied Miss Cannon a Harvard Corporation title as curator of the glass plates, he now refused to appoint Miss Payne to the university faculty. Moreover, Shapley reported, the president swore that Miss Payne should never ascend to a Harvard professorship while he was still alive.

  Miss Payne, though stymied in one direction, advanced along the avenues open to her. She took up Miss Leavitt’s work with photographic magnitudes, as Shapley had asked of her early on. Also at Shapley’s request, she began writing a new monograph—a follow-up to her Stellar Atmospheres—concerning stars of high luminosity.

  As Miss Payne pored over the spectra of the most luminous stars, she wondered whether their light might have been dimmed on its passage through space. Perhaps an unidentified absorbing medium, either fine dust or opaque gas, stole some of the luster from starlight. If so, then the bright O stars must be even brighter than they appeared, and therefore closer than imagined. Distance alone would dim them down by known proportions, as Newton’s inverse square law dictated: For two stars emitting equal light, the one twice as far from the observer shone one-quarter as brightly. Adding dust to the equation would make the farther star seem even farther removed.

  Others before Miss Payne had weighed the likelihood of “interstellar absorption” of light. The observatory’s own Edward King suspected a dimming effect, and had conducted photographic experiments over the years to detect it. Although King could not quantify the amount of light lost to space travel, he believed that some loss did occur. Shapley, on the other hand, argued confidently that no invisible interference dulled the glow of stars or spirals. In Shapley’s view, only the obvious patches of obscuring matter, such as the dark lanes contained within certain star clouds, could swallow light. Outside those zones, he was sure no obstruction occurred. All Shapley’s assessments of the distances to globular clusters, and of the Sun’s distance from the center of the Milky Way, assumed light’s unimpeded path through interstellar s
pace. Miss Payne thought it best not to contradict the D.D. on this point. In deference to him, she adopted his opinion, and also adduced evidence to support it.

  Shapley set as his goal the mapping of the whole Milky Way. He had made a good beginning when he removed the Sun from the galactic center, but that was only the first step toward a full picture. If one could see it from the outside, would the home galaxy assume a spiral form, with starry arms swirling about a bright central bulge? Or would it resemble one of the many blob-shaped, non-spiral galaxies? Or reveal a layout even more irregular? Shapley was counting on Cepheids and other variable stars to serve as waypoints on his quest. To that end he was seeking new assistants to identify new variables from the latest plates, and to track their changing magnitudes with Miss Payne’s new photometric standards. Charting the Milky Way from the inside out, Miss Payne opined, was a bit like limning all of London and its environs from a city street corner, through a heavy fog.

  • • •

  “JUST WHAT ARE YOUR PLANS NOW,” Shapley inquired of Priscilla Fairfield on May 26, 1928, “for the summer and for measuring proper motions of cluster type Cepheids and for spending some of your Gould Fund on a measuring girl at the Harvard Observatory?” He begged a quick reply, as he was en route to Europe for the general assembly of the International Astronomical Union, to be held in Leiden, and also the Heidelberg meeting of the Astronomische Gesellschaft: “I am leaving this side of the planet a week from tomorrow for two months.”

  Miss Fairfield wrote back on May 29 to say, “I have changed my plans and am going to the other side of the planet myself this summer. I hope this will only postpone and not prevent my measuring proper motions of cluster type Cepheids as I plan to return early in September.”

  July in Leiden saw the largest and most global gathering of astronomers ever united. For the first time the attendees, 243 in all, received star-shaped name badges to help them identify one another. New countries had signed on to the Union since its 1925 meeting, including Argentina, Egypt, and Romania. A new postwar spirit of rapprochement prevailed, enabling fourteen astronomers from Germany to participate freely in all discussions and activities—though they could not vote on policy, pending their government’s adherence to the Union. Willem de Sitter, president of the IAU and director of the Leiden Observatory, had personally invited them. De Sitter’s opening remarks recognized “the great German nation,” defining the country’s greatness in terms of “the number and importance of its contributions to astronomy.”

  The moment Miss Fairfield stepped off the train at the Leiden station, she attracted the attention of Dutch astronomy student Bartholomeus Jan Bok. He had been drafted by the local organizing committee as an official greeter of foreign delegates, particularly unaccompanied ladies such as the blond, petite Miss Fairfield and her Smith College superior, Harriet Bigelow. The genuine glow of his welcome only increased over the course of the week-long meeting. Everywhere Priscilla turned, “Bart” turned up beside her.

  In addition to Shapley and Miss Fairfield, the Harvard Observatory contingent at Leiden comprised Cecilia Payne, Margaret Harwood, Antonia Maury, and Adelaide Ames. At this, her first general assembly, Miss Ames was elected to IAU membership. Also, in recognition of her studies of spiral galaxies, she was duly appointed to the IAU Commission on Nebulae and Clusters. Shapley wrote to her parents in Massachusetts, to let them know how much she seemed to be enjoying herself.

  Miss Fairfield tried to fend off the amorous advances of her new suitor, who, at twenty-two, was a good ten years her junior. Bart Bok persisted, however, and at length overcame her misgivings.

  Bok made a different but equally favorable impression on Shapley. Having studied under Willem de Sitter and Ejnar Hertzsprung at Leiden, he had devoured Shapley’s papers about the Milky Way. Now pursuing a doctoral degree at the University of Groningen, Bok let Shapley know how earnestly he wished to work with him. Shapley, receptive as ever to the excitement of a young astronomer, thought that sounded like a fine idea.

  In the formal IAU sessions at Leiden, the world’s astronomers declared themselves still content with the Draper classification of the stars. Continued investigations had only confirmed its lasting practical value.

  The widely admired author of that system, meanwhile, remained at home in Cambridge. Miss Cannon tended to her increasingly infirm elder sister and examined additional faint stars for a new installment of the ongoing Henry Draper Extension. Helen Sawyer, who occupied the office next door to Miss Cannon’s, could hear her calling out the letter categories “day after day” to her recorder, Margaret Walton. Miss Cannon pronounced the classifications about as fast as Miss Walton could write them down. Jesse Greenstein, one of the Harvard underclassmen just starting his astronomy studies, once remarked that while the average person might judge from a distance whether a particular animal was an elephant or a bear, “Miss Cannon could separate the rogue from the good elephant, or the grizzly from the brown bear, at a glance.” Henry Norris Russell, on one of his regular visits to the observatory, suggested querying the aging Miss Cannon on her technique, but Miss Payne said it would be fruitless. She doubted Miss Cannon could explain her process, or even knew herself how she managed it. Her uncanny powers of instant recognition obeyed no conscious train of thought. She simply saw each star for what it was.

  Russell, on the other hand, relied more on logic. In the years since convincing Miss Payne to call her findings “almost certainly not real,” he had puzzled long and hard over the question of the hydrogen abundance. He gathered new data of his own during stays at Mount Wilson. More than once he concluded a series of calculations that suggested a predominance of hydrogen in the Sun and other stars. But each time this happened he rejected the results as spurious—until he could reject them no longer, and admitted the inescapable omnipresence of hydrogen. In a lengthy paper “On the Composition of the Sun’s Atmosphere,” which ran in the Astrophysical Journal in July 1929, Russell finally agreed with Miss Payne and cited her 1925 study. He made no mention of his earlier disbelief when he conceded, at the end of fifty pages, that “the great abundance of H [hydrogen] can hardly be doubted.”

  The constitution of the universe had inverted. The huge superabundance of hydrogen and helium, first intuited by Cecilia Payne, reduced all other cosmic components to chaff. What had long been presumed minimal was now proved plentiful by Russell’s deep analysis: the lightest, most immaterial elements reigned supreme.

  • • •

  “YOUR KIND OFFER OF THE Agassiz Research Fellowship made me very happy and I accept it with both hands,” Bart Bok wrote to Harlow Shapley on April 22, 1929. “Priscilla was delighted when she heard about the chance at Harvard. When it hadn’t come, she had promised to come to Groningen, but now that we have this wonderful opportunity, everything looks so much finer. I’ll never forget that you gave me a chance to work for the woman I love and I really shall do all I can, not to disappoint you.”

  The new graduate student arrived in the States on Saturday, September 7, married his betrothed on Monday at her brother’s house in Troy, New York, and a week later wrote to Shapley to say he was enjoying “a most wonderful and happy time” on honeymoon in the Berkshires.

  The stock market crash of October 1929 exerted no immediate ill effects on the observatory, where the mood remained expansive through December. Shapley, having proposed Cambridge as the venue for the semiannual meeting of the American Astronomical Society, invited the approximately one hundred members into the director’s residence for a New Year’s Eve party. The night’s entertainment cast the staff in a fully costumed and staged performance of The Observatory Pinafore. Book and lyrics for the operetta had been written fifty years earlier, in 1879, by former telescope assistant Winslow Upton, using music from the 1878 Gilbert and Sullivan hit about a Royal Navy ship named for a ladies’ apron. Upton apparently drew inspiration from the chorus of sisters, cousins, and aunts who boarded H.M.S. Pinafore,
and he turned them into a bevy of female computers for his purposes. In place of the two boy babies switched at birth, Upton twisted a zany new intrigue around a pair of prisms stolen from one of Pickering’s photometers.

  Upton’s libretto spoofed everything and everyone in the observatory. Since his stint there had overlapped Williamina Fleming’s clerkship prior to her son’s birth, he made sure to cite “our Scotch maid,” who “has unfortunately returned to her native land.”

  An early scene finds young Upton, who lived in a garret off the stairway to the Great Refractor, ruing the noisy activities that wake him in his off-hours. Arthur Searle hears him out and suggests he find a room off-site. Upton vows, “I shall when my salary is large enough,” to which Searle retorts, “I guess you’ll die of old age in that room if you wait for a large salary before giving it up.”

  For all that had changed at the observatory since Upton’s day, the wages of astronomy remained an evergreen theme. The point was driven further home in the lyrics: “An astronomer is a sorry soul, / As free as a caged bird; / His sympathetic ear should be always quick to hear / The directorial word. / He must open the dome and turn the wheel, / And watch the stars with untiring zeal, / He must toil at night though cold it be, / And he never should expect a decent salaree.”

  The current crew enjoyed reviving all the ghosts of New Years’ past, especially the gentlemanly Pickering, whose strongest oath when provoked to anger in the drama is, “Oh Polaris!”

  At an encore performance on Monday, January 13, for the monthly meeting of the Bond Astronomical Club, half again as many guests squeezed into the director’s residence. “After that night,” Shapley pledged with mock solemnity, “we resume our sober and methodical attempts to maintain the scientific standing of the Observatory.”

  Foreigners now looked on Harvard as “the meeting place of the astronomers of the world.” They deemed its multinational character unusual, even in the decidedly international science of astronomy. Shapley was happy to receive Svein Rosseland from Norway in 1930, and Ernst Öpik from Estonia, even though, as he half-joked to George Agassiz, it was difficult “finding places for our present staff and scientific visitors to sit down.” The workforce had about trebled in size over the course of his directorship.