The Glass Universe
Page 29
Some of the former employees of the observatory were willing to come back to work after the war at their former low salaries. One of these, Ellen Dorrit Hoffleit, returned in 1948 for the love of astronomy, at half her army pay. Dr. Hoffleit, a 1928 graduate of Radcliffe, had moved into the observatory straight out of college. She started on variable stars, but soon switched to meteors and later to the determination of stellar brightness by the widths of spectral lines. Her wartime work had taken her from the MIT Radiation Laboratory to the Ballistic Research Laboratory of the army’s Aberdeen Proving Ground in Maryland, to the White Sands Missile Range in New Mexico. She had computed everything from firing tables for navy cannons to the velocities of captured V-2 rockets. Now that she was once again sighting objects native to the sky, she availed herself of help from rented IBM computing equipment in analyzing data on stellar distribution. The days of the human computer were numbered—by zeros and ones.
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FORMER PICKERING FELLOW Helen Sawyer Hogg took the news of her Annie Jump Cannon Prize not exactly in stride. Pleasure jostled with anxiety and the lethargy that had come over her in the past few months. “All Spring I have felt very doleful,” she told Shapley in a letter dated July 25, 1949. She had seen him just recently at the June gathering of the American Astronomical Society, in Ontario, where she now lived. “I left the Ottawa meetings more depressed than when I went; and the night observing which I have been tackling systematically since my return has served only to convince me once more that I cannot fit in night work with my heavy family responsibilities. In other words, I seem to have reached the end of my tether.” Helen and her husband, Frank, a native Canadian, had moved to Victoria, British Columbia, in 1931 to work at the Dominion Astrophysical Observatory. Only Frank had a job there, but Helen also worked full-time as a volunteer. She was the first woman allowed to use the 72-inch reflector. When the Hoggs’ daughter, Sally, was born in 1932, Helen continued her observing runs with Sally in a basket beside her. Sympathetic observatory director John Stanley Plaskett got Mrs. Hogg a $200 grant, so she could hire a housekeeper to mind the baby. In 1935 Frank was offered a professorship at his alma mater, the University of Toronto, and the family moved back East. Helen, too, was hired in Toronto. She became a research officer in the astronomy department and the university-affiliated David Dunlap Observatory in 1936, the year of David Hogg’s birth. The Hoggs had another boy, James, in 1937, and Helen published her “Catalogue of 1116 Variable Stars in Globular Clusters” in 1939. The outbreak of war gave her the opportunity, in 1941, to teach astronomy classes at the university, which she had continued ever since. “I have asked Frank to get me an indefinite leave of absence from my university position here, but he is very much upset at the thought.” The Annie Jump Cannon Prize seemed to add a new weight of obligation. “In my opinion, this award carries with it a certain amount of responsibility, when made to a person my age, that is. [She was forty-four.] In other words, it does not look so good to take the award and quit!” Conflicted, she had not yet responded to the AAS secretary, C. M. Huffer, regarding her expected acceptance. “It has probably not crossed his mind that circumstances might make it advisable for me to refuse the award.”
Shapley himself felt dispirited by his current distance from active research, but he was as capable as ever of heartening a former student, especially one who shared his long-term devotion to globular clusters. “There is little doubt but that you are undertaking too much in running a family at this critical stage,” he replied on July 29, 1949, “and doing everything else. A leave of absence from the University work is obviously a good idea; but a study, with astronomical literature in it, and some photographs of clusters and the computing machine—that should not be given up, even if it must be established in one corner of some room at home. And also probably there is some interesting and not too laborious writing about old books* that should be done, just to keep the finger in the game until strength and time are less expensive. About that award—don’t be silly, even if the weather is hot. The award is made for past accomplishments, and carries with it no responsibility for future activities. Suppose I should commence turning in medals because I have degenerated into being just a blank, blank director, personality smoother, instigator of labors by others. Let’s both cheer up. One particular reason for such a resolve is that after fifteen or twenty lectures on cosmogony in the Harvard Summer School I have convinced myself that this is unquestionably the best universe I know of.”
Shapley had introduced the graduate summer program in astronomy and astrophysics in 1935. It collapsed during the war, but roared back to life afterward, and currently enrolled more than a dozen students. Just as Pickering had made the observatory’s name synonymous with photometry and photography, Shapley tied it securely to graduate education. He had fostered a generation of Harvard astronomers.
Mrs. Hogg accepted her Annie Jump Cannon Prize at the June 1950 meeting of the AAS, held at the University of Indiana in Bloomington. Not long afterward, on New Year’s Day 1951, her husband, then the forty-six-year-old director of the David Dunlap Observatory, died of a heart attack. She assumed many of his professional duties, including the teaching of his courses and the writing of his weekly astronomy column for the Toronto Star, but not the directorship, which went to someone else.
In August 1951 Shapley gave notice that he would retire as director of the Harvard Observatory at the end of one more year, shortly before his sixty-seventh birthday. To his chagrin, the university hesitated to name a successor, either from within the ranks or from another institution. Months passed in which the staff grew increasingly insecure. At the same time, the lack of a designated new leader diminished the observatory’s standing in the eyes of prospective students and astronomers generally. In March 1952 President Conant appointed an ad hoc committee, chaired by his wartime colleague J. Robert Oppenheimer, to evaluate the entire Harvard astronomy program. As Shapley prepared to vacate his position that August, Donald Menzel of the Observatory Council was named temporary acting director.
Menzel shepherded the observatory through the ensuing period of upheaval. The next two years saw the demolition of the old wooden structures, the erection of brick office buildings alongside the Great Refractor, the eviction of the American Association of Variable Star Observers from the observatory grounds, and the abandonment of the Boyden Station in South Africa. Menzel was officially named the sixth director in January 1954, and in 1955 the Harvard College Observatory formed a beneficial new association with the Smithsonian Astrophysical Observatory, which moved from Washington, D.C., to Cambridge. At the Oak Ridge site, renamed the Agassiz Station in memory of patron George R. Agassiz, a large new telescope marked Harvard’s entry into the emerging science of radio astronomy. Where a 60-inch optical reflector had once been dominant, an antenna 60 feet in diameter now collected faint radio signals from deep space.
Cecilia Payne-Gaposchkin became a full professor in 1956, the first woman at Harvard to be promoted to that level. She sent handwritten invitations to all the female astronomy students to join her for a celebration in the observatory library, where she pulled herself up to her full height, squared her broad shoulders, and said with a twinkle, “I find myself cast in the unlikely role of a thin wedge.”
As full professor, she was eligible to become department chairman, which title was thrust on her the following fall. Although she had long craved the prestige of that position, the cares of office alternately bored her and strained her nerves. What was worse, they took time away from her research.
In 1958 the Harvard Corporation under President Nathan M. Pusey at last elected Cecilia Payne-Gaposchkin the Phillips Professor of Astronomy. Even then her salary of $14,000 a year, while higher than her husband’s, remained far below that of her male peers.
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CATHERINE WOLFE BRUCE’S investment in astronomy came too late in life to answer her questions about the universe. The medal she endowed
, however, continues today to attach her name to every significant advance in her adopted science. Among the more than one hundred Bruce gold medalists who have been celebrated for their lifetime achievements, Arthur Stanley Eddington deciphered the internal structure of the stars, realizing that their mass at the time of their birth determines their ultimate fate; Henry Norris Russell charted the course of stellar evolution, showing that stars do change from one color to another as they age; and Hans Bethe explicated the process of nuclear fusion by which stars generate their heat and light. In addition to Edward Pickering, Harvard College Observatory winners of the Bruce Medal include Harlow Shapley, Bart Bok, and Fred Whipple, who propounded the “dirty snowball” model of comet construction.
To date, only four women have received the Bruce Medal. The first, in 1982, was Margaret Peachey Burbidge, a native of England who studied the spectra of galaxies and, in collaboration with her husband, Geoffrey, and their colleagues William Fowler and Fred Hoyle, showed that all heavy elements are produced in the interiors of stars. In 1990 the Bruce Medal went to Charlotte Moore Sitterly. As Princeton computer Charlotte Moore in 1929, she took advantage of Henry Norris Russell’s absence on sabbatical to enroll at the University of California, Berkeley, where she earned her Ph.D. in 1931, doing research on the spectra of sunspots. After she returned to Princeton and married astronomer Bancroft Sitterly in 1937, she continued working, and later became manager of the program in atomic spectroscopy at the National Bureau of Standards. Vera Rubin, who attended Vassar College because of its historic association with Maria Mitchell, received the 2003 Bruce Medal for her measurements of galaxy rotation, which led to the discovery of dark matter. Sandra Moore Faber, the 2012 winner, did her graduate work at Harvard but has spent her career at the University of California Observatories, pursuing the formation, structure, and clustering of galaxies. In 2013 she was one of twelve recipients of the National Medal of Science.
The telescope named for Miss Bruce, which Shapley praised as “the great galaxy hunter of the Southern Hemisphere,” was decommissioned in 1950. It gave up its mount at Bloemfontein to a new 30-inch instrument that promised to provide even better photographs in shorter exposure times. The intact Bruce lens and tube stood idle for several years in Africa before being shipped back to the States, for continued idleness at Oak Ridge. The Bruce’s old dome in Arequipa was converted to a chapel.
Miss Bruce herself lies buried, as she prearranged, at Green-Wood Cemetery in Brooklyn, New York, the final resting place of the city’s wealthiest, most prominent citizens of her day. Dr. and Mrs. Henry Draper are also buried there, together, under a joint pentagonal marker with a carved facsimile of the congressional medal commending Dr. Draper’s part in the 1874 transit of Venus.
The Draper Medal, like the Bruce Medal, continues to acknowledge astronomers for lifelong accomplishments. Those researchers who have won both the Draper and the Bruce include Edward Pickering, George Ellery Hale, Arthur Stanley Eddington, Harlow Shapley, and Hans Bethe. No women have ever taken both prizes. In the years since Miss Cannon was awarded the Draper Medal, only one other woman has received it—radio astronomer Martha P. Haynes of Cornell University, who shared the 1989 honor with Riccardo Giovanelli for their joint mapping of the large-scale distribution of galaxies.
The Annie Jump Cannon Prize likewise endures. It was awarded to Miss Cannon’s former recorder, Margaret Walton Mayall, in 1958, and to Nantucket observatory director Margaret Harwood in 1961. The frequency of selection has increased since 2006, when the American Astronomical Society began choosing a new winner every year. The annual cash award now exceeds $1,000 (the amount originally contributed by Miss Cannon), but is no longer accompanied by a handmade pendant. In 2016 Laura A. Lopez of Ohio State University won the Cannon Prize for her studies in radio and X-ray astronomy regarding the life cycles of stars.
On Observatory Hill in Cambridge, Massachusetts, today, the Harvard-Smithsonian Center for Astrophysics stands as the successful union of the former Harvard and Smithsonian observatories. The CfA employs three hundred scientists engaged in university- and government-supported research covering every area of astronomy. Approximately one-third of the staff is female.
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THE MONUMENTAL WORK of stellar classification known as the Henry Draper Catalogue and Extension, begun under Williamina Fleming in the 1880s and continued through 1940 by Annie Jump Cannon, is still in regular use. Every astronomy student learns the temperature order of the stars by memorizing Oh, Be A Fine Girl/Guy, Kiss Me. A contest to come up with a cleverer, less sexist mnemonic was held for several years in Harvard’s introductory astronomy course, but the anonymous original retains its utility and pride of place. The thousands of Henry Draper identification numbers, assigned to the stars by the female computers, remain in effect as well. Star number HD 209458, for example, a variable in the constellation Pegasus, made news when modern detection methods located a planet in orbit around it.
Antonia Maury’s classification system, with its twenty-two spectral types and several subtypes, struck her contemporaries as too complex to gain traction. Some of its distinctions proved crucial, however, in discerning the different magnitudes and ages of stars that shared the same general categories. After Ejnar Hertzsprung first complimented Miss Maury’s acumen in 1908, the Draper classification made room for one of her notations in 1922, and in 1943 the MKK innovation incorporated additional Maury-type gradations. In 1978, some twenty-five years after her death, her system won further vindication when William Morgan published the Revised MK Spectral Atlas for Stars Earlier Than the Sun with new coauthors Helmut Abt and J. W. Tapscott. Morgan dedicated this volume “To Antonia C. Maury (1866–1952) Master Morphologist of Stellar Spectra.”
Henrietta Leavitt did not participate in the classification effort, but her pursuit of variable stars and her discovery of the relationship between period and brightness among the Cepheid variables has had an equal, if not greater, impact on progress in astronomy. Once calibrated and applied to the problem of measuring distances across space, Miss Leavitt’s period-luminosity relation allowed Harlow Shapley to extend the boundaries of the Milky Way. The same Cepheid stars, subjected to the same analytical techniques, enabled Edwin Hubble to appreciate the enormous distances to the spiral nebulae. Hubble used Cepheids in 1924 to show that the Milky Way was not the only galaxy in the universe, and later to demonstrate that the universe was expanding to ever vaster proportions, as evidenced by the speedy outbound flight of most external galaxies. The Cepheids, however, had still more to say about cosmic distances. During World War II, Walter Baade, a German immigrant who had been working at Mount Wilson since 1931, took advantage of dark skies made darker by area-wide blackouts. Baade’s detailed study of the stars of the Andromeda Galaxy split the Cepheids into two subgroups. He accordingly recalibrated the distance scale and arrived at an overall size of the universe that doubled Hubble’s estimate. Today, astronomers rely on the period-luminosity relation to measure the current expansion rate of the universe.
The relationship between redshift and distance that Hubble saw in the realm of the nebulae has come to be known as Hubble’s law. By the same token, some scientists argue, the relationship between period and brightness that provided the basis for Hubble’s discoveries should rightly be renamed the Leavitt law. Awareness of this proposed terminology has been spreading since January 2009, when the executive council of the American Astronomical Society unanimously passed a resolution in favor of the change. The occasion was the one-hundredth anniversary “of Henrietta Leavitt’s first presentation of the Cepheid Period-Luminosity relation, a seminal discovery in astronomy that continues to have great significance.” Although the councilors allowed that the AAS had “no authority to define astronomical nomenclature,” they said that they personally “would be very pleased” to see the designation “Leavitt Law” in wide use.
When the female computers of the Harvard College Observatory come
up in present-day conversation, they are often portrayed as underpaid, undervalued victims of a factory system. Pickering stands accused of giving them scut work that no man would stoop to do, yet this is far from true. Before astronomy morphed into astrophysics around the turn of the twentieth century, both men and the few women engaged in the science were willing slaves to routine. Arthur Searle, the acting director during the interregnum between Winlock and Pickering, tried to explain this reality to a journalist intent on chronicling the excitement of observatory life. “It is only fair to warn you,” Searle admonished Thomas Kirwan of the Boston Herald, “that your proposed article cannot be at once true and entertaining. The work of an astronomer is as dull as that of a book-keeper, which it closely resembles. Even the results reached by astronomical work, although they relate to more dignified subjects than the ordinary affairs of trade, are far less interesting than the result of book-keeping, at least to the general reader, unless they are so disguised by fancy as to have little to do with science.”
Pickering, though enthralled by the incremental gains he could make nightly at the controls of his photometer, ushered in a new era of photography and spectroscopy that transformed the observatory. Having found several female assistants already in place when he took charge, he brought in more of them and entrusted the stellar classification to their judgment. He also attracted assistance in variable star observation from alumnae and female professors of the women’s colleges. His treatment of women, widely perceived as more than fair, invited fellowship funding that further advanced women’s participation in astronomy. When Harlow Shapley came to Harvard, he was able to redirect the fellowship money into a program of graduate education that initially—and necessarily—favored women over men as applicants. Cecilia Payne’s attainment of the first astronomy Ph.D. at Harvard, in the course of which she challenged the very fabric of the universe, could be traced directly to Pickering’s “harem” and the observatory’s singular collection of glass plates.