The Glass Universe

by Dava Sobel

  “On the other hand,” Pickering conceded, “Dr. Stewart would doubtless feel aggrieved if after all the labor especially in following the Bruce plates, he is not allowed to examine them. The delay might also prevent the early discovery of a new star or other object of special interest.”

  Bailey, for his part, sympathized with Mrs. Fleming’s vexation, but thought it unfair to deny credit for producing “first class plates,” while publicly recognizing “the mere picking up of new objects by certain well known characteristics.” Here Pickering had to agree, and he promised to change observatory policy accordingly. From now on, individual assistants who demonstrated special skill or care in photography would indeed receive proper acknowledgment in Harvard announcements.

  • • •

  MISS MAURY HAD OFTEN FEARED she might not receive credit for the years of effort she invested in her classification system. But in 1897, when her “Spectra of Bright Stars” was published in the Annals of the Harvard College Observatory, “Antonia C. Maury” stood out in bold black and white, right on the title page, above the name of Edward C. Pickering, Director. It marked the first time that a woman had authored any part of the Annals. In 1890, in contrast, the contributions of “Mrs. M. Fleming” to “The Draper Catalogue of Stellar Spectra” had been described and gratefully acknowledged only in the director’s introductory remarks.

  Pickering’s preface to the new volume noted that Miss Maury had been assigned in 1888 to study the spectra of the bright northern stars as part of the Henry Draper Memorial, “and she is alone responsible for the classification.” Given that her investigations had been made several years prior, he said, they predated “the recent discoveries respecting the spectrum of helium.” Rather than rewrite the lengthy treatise in the light of helium, Miss Maury had appended a discussion and some new thoughts in six pages of “Supplementary Notes.”

  After her return from Europe in 1895, Miss Maury retreated to the old Draper homestead in Hastings-on-Hudson, where her mother had grown up. The domes of her uncle Henry’s telescopes now stood empty at the top of the hill, but the several cottages on the property still belonged to her elderly great-aunt, Dorothy Catherine Draper. Miss Maury found work in nearby Tarrytown-on-Hudson, teaching chemistry and physics at Miss C. E. Mason’s Suburban School for Girls.

  Nostalgia carried Miss Maury back to Vassar, also nearby in Poughkeepsie, for the astronomy department’s annual dome party. In her college days she had studied under Maria Mitchell, the first lady of American astronomy, who instituted the dome parties and the practice of asking all the student guests to write poems on scraps of paper. Miss Maury felt inspired to revive that tradition. Her 1896 “Verses to the Vassar Dome” began, “A low-built tower and olden, / Dingy but dear to the sight, / And they that dwell therein are wont / To watch the stars at night.”

  The late Professor Mitchell had been just under thirty when she attained world fame and a gold medal from the king of Denmark for her 1847 discovery of “Miss Mitchell’s Comet.” Miss Maury had herself only recently turned thirty, but her career seemed to be veering away from astronomy. Perhaps her publication in the Annals would steer it back in the direction she intended years earlier, when “with searching glass I scanned / Those far deep lanes of night, / Where stars well up through endlessness, / In springs of living light.”

  Pickering invited Miss Maury briefly back to Harvard in mid-August 1898, to speak about her early research at a collegial meeting of distinguished astronomers intent on forming a national professional society. Everyone came, from Simon Newcomb, the elder statesman of the science, to thirty-year-old George Ellery Hale. Hale, who so successfully organized the country’s first astronomy meeting in Chicago in the summer of 1893, had hosted another one in 1897, at the dedication of the grand new Yerkes Observatory in Williams Bay, Wisconsin, where he was now director. His arrival in Cambridge in 1898 coincided with a severe heat wave that lasted throughout the three-day gathering. Pickering’s welcome proved equally warm. As the attendees were too numerous to be accommodated en masse in the observatory, the director ushered all hundred-plus of them into the parlor of his home.

  “The spacious mansion of Professor Pickering formed an ideal place for the meeting of a convention,” writer Harriet Richardson Donaghe reported in Popular Astronomy, “while the gracious dignity of the director and the hospitality of his stately wife, who received their guests with a cordial greeting, gave the serious purpose of the assemblage a touch of festivity and saved even the non-scientist from feeling out of his element.” Miss Donaghe herself was one of the few nonscientists present. The situation called to her mind Walt Whitman’s poem about the “Learn’d Astronomer,” and she quoted part of a line from it in her article: “‘Charts and diagrams, to add, divide and measure,’ gave evidence of the heavy work laid out for the savants, but behind them gleamed the snowy outlines of the bust of some honored ancestor, the rich coloring of a family portrait, or the sparkle of a jewelled miniature, in the artistic setting of a private drawing room.”

  Members of Harvard’s own observatory staff peopled the roster of speakers, beginning with Professor Searle, who delivered a talk on the “personal equation,” or the way an individual observer’s visual acuity, eye-hand coordination, and speed of reaction affected his perceptions. Mrs. Fleming prepared an announcement of the numerous new variables with bright hydrogen lines found on Bruce and Bache telescope plates from Arequipa. The director read her paper aloud at the podium, adding a coda of his own. As Miss Donaghe reported, “In conclusion Professor Pickering said that Mrs. Fleming had omitted to mention that of these seventy-nine stars nearly all had been discovered by herself, whereupon Mrs. Fleming was compelled by a spontaneous burst of applause to come forward and supplement the paper by responding to the questions elicited by it.” Later Solon Bailey, only recently returned from his five-year tour of duty in Peru, discussed his pet subject, “Variable Stars in Clusters,” and at the end Miss Maury held forth “On the K Lines of Beta Aurigae.”

  A coterie of participants, including Newcomb and Hale, met privately with Pickering to define the national astronomical society and draft its constitution. They did all that in a single day, though they could not settle on a name.

  By the time the members of the nascent organization dispersed to their home institutions, the entire astronomy community knew that an important new solar system body had come to light in Europe. Gustav Witt of the Urania Observatory in Berlin and Auguste Charlois at Nice were both out hunting asteroids with telescope and camera when they picked up the object’s trail on the night of August 13, 1898. Max Wolf’s detection of Brucia in 1891 had proven the superiority of photography for such pursuits: On a plate exposed for two hours or more, a fast-moving asteroid would stand out as a very short line against the backdrop of the distant point-like stars. Upon developing their plates, both Witt and Charlois detected the same small streak of evidence, but Witt filed the first claim, with the result that other astronomers joining the chase in the following days referred to the quarry as “Witt’s planet.” The newfound body quickly distinguished itself as the speediest of its kind, and therefore bound to pass nearer to Earth than any of the others.

  Seth Carlo Chandler, a specialist in defining the orbits of comets and asteroids, rushed to determine the true path of Witt’s planet. Once he had worked out a preliminary ephemeris, or table of its predicted positions, from the current spate of sightings, he estimated that the object, now barely discernible at eleventh magnitude, probably had whistled close by Earth in 1894. No one noticed it then, but Chandler hoped a trace of its passage might be preserved on one or more photographic plates in the unique astronomical archive of the Harvard College Observatory. He would need to smooth over his earlier dispute with the director over the Harvard Photometry to gain access to the glass universe.

  “I deem it my duty, in the interest of science,” Chandler wrote to Pickering on November 3, 1898, “to send you the encl
osed ephemeris of the planet . . . which all astronomers will be interested in, in common, for the recovery of any previous observations of this most important body.” Pickering of course assented, and directed Mrs. Fleming to search through the plate stacks. With Chandler’s rough map in hand, she selected the likeliest photographs among the hundred thousand in storage, and spent months combing through them for signs of Witt’s planet. In early January 1899, on plates dated 1893, she finally found the elongated blob that she took to be the asteroid, and measured its positions. Chandler then incorporated the additional data into a corrected orbit, which he sent back to her. Armed with the improved map, Mrs. Fleming once again located the object, which had been named Eros in the interim, on plates from 1894 and 1896.

  “I thought the asteroids were always feminine,” Miss Bruce exclaimed when she heard the news. And it was true that all 432 previous discoveries (beginning with the first one, Ceres, in 1801) had been given women’s names. “Fortunately poor dear little Eros is so far from the rest,” she added, “or his life might be made miserable among all those old maids. It is pleasant that you photographed him so long ago while he was yet happy—unknown to fame.”

  Mrs. Draper wrote to say she was glad the ever-growing trove of photographs had cornered Eros, noting “the small god himself could scarcely have been more troublesome.” Chandler agreed. He thought Pluto a more suitable name than Eros for the asteroid, “for malignity alone.”

  As Chandler redefined Eros’s orbit around the Sun, he predicted the asteroid would come to pass very near Earth in the autumn of 1900. At that close range, Eros might be pressed to answer the oldest riddle in astronomy: What is the distance between Earth and the Sun?

  The remoteness of the heavenly bodies made their distances all but impossible to gauge. The most the ancients could say was that the planets must be closer than the stars, since the planets, or “wanderers,” could be seen moving with respect to the stars, while the constellations ever maintained their same configurations. In the third century BC, Aristarchus of Samos judged the relative remove of the Sun and the Moon by geometry, concluding that the Sun was probably twenty times farther away than the Moon.

  In the 1500s, when Copernicus proposed the planets circled the Sun and not Earth, he estimated the relative distances between these bodies. Jupiter, for example, must lie 5.2 times farther than Earth from the Sun, and Venus only a fraction (0.72) of Earth’s solar distance. But Copernicus still had no idea how far away to place the stars. Nor could Kepler, who derived the laws of planetary motion in the early 1600s, offer more than relative proportions for the distances separating the members of the solar system. Determining the true width of a single interplanetary gap would define all the others at a stroke. And a firm figure for the Earth-Sun distance would constitute a crucial milestone en route to the stars.

  An opportunity to define the much desired Earth-Sun distance, or astronomical unit, arose late in the eighteenth century, on the occasion of the 1761 transit of Venus. Twice in about a hundred years, the orbits of Earth and Venus allow the sister planet to be seen crossing the face of the Sun over a period of several hours. English astronomer royal Edmond Halley foresaw the phenomenon’s potential for resolving the distance dilemma. He imagined observers venturing far to the north and south of the globe to watch the transit and record the exact times of its various stages. The wide geographical separation between the observing parties would cause each to see Venus transit the Sun at a slightly different solar latitude. Later, by comparing their notes and triangulating, they could deduce the distance to Venus and extrapolate the Earth-Sun distance. “I wish them luck,” Halley said in laying out his scheme, “and pray above all that they are not robbed of the hoped-for spectacle by the untimely gloom of a cloudy sky.”

  Clouds indeed intervened in some places to foil the observations. Even where clear weather prevailed, the hundreds of astronomers who heeded Halley’s call failed to achieve precise measurements, so that neither the 1761 transit nor the next one in 1769 yielded the desired result. The great effort and expense did succeed, however, in narrowing the Earth-Sun distance to a range of possibilities somewhere between ninety and one hundred million miles.

  When the transits predicted for 1874 and 1882 again united scientists in the quest for a conclusive determination, Simon Newcomb took charge of American expeditionary preparations. In the run-up to the events, he commissioned the firm of Alvan Clark to build instruments and invited Dr. Henry Draper to Washington to teach the several teams how to photograph the Sun. In the aftermath, in the 1890s, Newcomb asked Miss Bruce to pay salaries for a staff of computers to reduce the accumulated observations. This process was still in progress when Eros entered the scene, promising to shave many thousands of miles of uncertainty off the long-sought figure.

  Planning the Eros campaign of 1900–1901 mobilized the world’s astronomers, though not in the mounting of expeditions. No one needed to go anywhere. Unlike an eclipse or a transit, which transpired in a matter of minutes or hours, the autumn visit of Eros would occupy several months’ worth of nights. Observatories throughout Europe, Africa, and across America were already ideally situated, and already outfitted with the large telescopes required for sighting a dim, tiny asteroid against a starry backdrop. An international consortium of cooperating astronomers would monitor Eros’s changing position in relation to large numbers of reference stars. In the United States, only the Harvard College Observatory was equipped to track Eros by means of photography.

  The escalating enthusiasm for Eros made Miss Bruce wish that her own asteroid, Brucia, “would show herself again.” But the time was not right. Miss Bruce’s namesake hid far out of sight. Miss Bruce also withdrew. She fell ill again and died at her home in New York on March 13, 1900.

  “It is no easy thing to choose fitting words to refer to the close of any life on Earth,” Popular Astronomy editor William W. Payne wrote in his obituary notice, “much more is it difficult to offer a right and worthy tribute to the memory of one like Miss Catherine Wolfe Bruce, who, for noble cause, the world of science has learned to love for what she was and for what she did.” Payne, whose own Goodsell Observatory at Carleton College in Northfield, Minnesota, had once received aid from Miss Bruce, praised “her intelligent generosity,” which “knew no limits of race or country, and so science the world over mourns a common loss. Her kind and thoughtful care lightened many a burden in her own land, awakened new zeal in needful research, and helped to finish many a task when patience and other resources were nearly gone.” In closing his brief sketch of her life, Payne itemized the long list of her gifts to astronomy. They totaled more than $175,000—the equivalent of a royal ransom.

  PART TWO

  Oh, Be A Fine Girl, Kiss Me!

  It was almost as if the distant stars had really acquired speech, and were able to tell of their constitution and physical condition.

  —Annie Jump Cannon (1863–1941)

  Curator of Astronomical Photographs, Harvard College Observatory

  The fact that I was a girl never damaged my ambitions to be a pope or an emperor.

  —Willa Cather (1873–1947)

  Winner of the American Academy of Arts and Letters Gold Medal for Fiction

  CHAPTER SIX

  Mrs. Fleming’s Title

  MINA FLEMING’S STAR was on the ascendant. In 1899, at Pickering’s urging, the Harvard Corporation formally appointed her to a newly created position as curator of astronomical photographs. She thus became, at age forty-two, the first woman ever to hold a title at the observatory, or the college, or the university at large.

  At this same time, the turning of the century inspired the Harvard administration to assemble a time capsule of campus life, with photographs, publications, essays, and diaries solicited from students, faculty, and staff. Mrs. Fleming dutifully wrote out her contribution for the “Chest of 1900” over a period of six weeks.

  “In the Astrophotogra
phic building of the Observatory,” she began March 1, 1900, on a lined yellow notepad, “12 women, including myself, are engaged in the care of the photographs; identification, examination and measurement of them; reduction of these measurements, and preparation of results for the printer.” Every day they bent to their examination tasks in pairs, one with a microscope or magnifying glass poised over a glass plate in its frame, and the other holding a logbook propped open on a desktop or in her lap, recording the spoken observations of her partner. A hum of numbers and letters, like conversations in code, pervaded the computing room.

  “The measurements made with the meridian photometer,” Mrs. Fleming continued, “are also reduced and prepared for publication in this department of the Observatory.” Florence Cushman, who had previously worked for a business firm, received the sheaves of magnitude measurements made nightly with photometers in Cambridge and Peru. She and Amy Jackson McKay copied over the visual observers’ judgments, calculated the corrections, and checked and rechecked the figures before consigning them to the printer. The rest of the female computing staff, consisting of the sisters Anna and Louisa Winlock (daughters of the previous director) and the ladies who helped them process the data regarding star positions, remained in the west wing of the original observatory, as the Brick Building’s limited space could not accommodate everyone.

  “From day to day my duties at the Observatory are so nearly alike that there will be but little to describe outside ordinary routine work of measurement, examination of photographs, and work involved in the reduction of these observations.” If Mrs. Fleming’s days blended in sameness, as she claimed, they bore no resemblance to those of any other invited contributor to the Harvard time capsule. “My home life is necessarily different from that of other officers of the University since all housekeeping cares rest on me, in addition to those of providing the means to meet their expenses.” She had to plan and purchase all provisions, plus give instructions to Marie Hegarty, the Irish maid she retained to clean house and cook the evening meal six nights a week. Although Mrs. Fleming was contracted to work seven hours a day at the observatory, she rarely arrived past 9 a.m. or left before six in the evening. “My son Edward, now a junior in the Mass. Inst. of Technology, knows little or nothing of the value of money and, therefore, has the idea but that everything should be forthcoming on demand.” The frugal Mrs. Fleming minimized her expenses by inviting Annie Cannon to board with her on Upland Road. Miss Cannon proved companionable and came from a good family. Her father, Wilson Lee Cannon, was a bank director and former state senator in Delaware.