The Glass Universe: : How the Ladies of the Harvard Observatory Took the Measure of the Stars
By Dava Sobel, Viking, 336 pages, $30
Astronomy has always had a labour shortage: so many stars, so few people to observe them. And so little time: what is a puny human lifetime compared with that of the universe, or even of a mere planet? It takes generations of diligent observers to detect the regularities that unfold over millennia — for example, the precession of the equinoxes: it takes nearly 26,000 years for the constellations to appear to rotate around the Earth. As with spotting rarely visible phenomena, such as supernovae, it also requires techniques of record keeping and transmission that transcend the longevity of civilisations and the durability of most materials. Nasa’s “Five Millennium Canon of Lunar Eclipses” (2000BC-AD3000) includes observations originally recorded on cuneiform clay tablets by ancient Mesopotamian astronomers. (Compare the average physical lifetime of a CD, about 30 years.) Civilisations rise, civilisations fall, but astronomy endures.
The invention of astrophotography in the mid-19th century intensified both the labour and archival challenges that had always confronted astronomers. Suddenly it became possible, with comparatively little effort, to capture millions more stars: whole swaths of the sky (including in the southern hemisphere, thanks to new observatories in colonial outposts such as South Africa and Australia) could be covered systematically; stars too faint to be seen even with the best optical telescopes could be coaxed into visibility by increasing the exposure time and emulsion sensitivity of photographic plates. Even more miraculously, the photographs could, with the use of diffraction gratings, yield stellar spectra striated by those characteristic dark lines that are the signatures of various elements.
In gleeful defiance of naysayers such as the French philosopher Auguste Comte, who only a few decades before had proclaimed the impossibility of astrophysics, astronomers set out to investigate what the stars were made of. Enterprising observatory directors all over the world launched grand astrophotographic initiatives to create new star maps, catalogues and spectroscopic classifications. In Paris, Potsdam, Oxford, Algiers, Helsinki, Melbourne and Cambridge, Massachusetts tonnes of glass plates dotted with the imprint of millions of stars and their spectra piled up — and with them an urgent demand for highly skilled, conscientious and cheap labour to analyse them. These archives of glass plates are the “glass universe” of Dava Sobel’s title; the solution to the labour problem provides her subtitle. Focusing on the Harvard Observatory, she describes how two open-minded and pragmatic directors, Edward Pickering (from 1877 to 1919) and Harlow Shapley (1921-52), recruited scores of women at cut-rate wages to calculate, measure, classify and make sense of the glass universe produced by astrophotography. These men gave such women as Williamina Paton Stevens Fleming, Antonia Maury, Henrietta Swan Leavitt, Annie Jump Cannon and Cecilia Payne a chance to support themselves (barely) with work they could dedicate themselves to day and night. They were to leave their mark on astronomy with still widely accepted classifications of stellar spectra, the discovery of the period-luminosity relationship among variable stars, and the earliest estimates of stellar composition that pointed to the predominance of hydrogen and helium. These women spent most of their lives at the Harvard Observatory; a great many others stayed for a shorter time, leaving for better career prospects, marriage, or both.
It’s a familiar story to historians of science (and to most astronomers), but Sobel tells it with brio and sympathy, making excellent use of the rich archival materials preserved mostly at Harvard. Her narrative is driven by personalities, and it is undeniable that Fleming’s true grit, Maury’s perfectionism, Cannon’s preternaturally sharp eye for patterns, as well as Payne’s brilliance and enthusiasm were personal qualities essential to their contributions — just as Pickering’s business sense and Shapley’s dynamism (rather than either’s seminal scientific achievements) helped establish the upstart Harvard Observatory as a world leader in the new field of astrophysics.
But other, more structural factors were also at work: where did all those well-educated, scientifically proficient women come from? Who supplied the money for the new telescopes, additional salaries, publication series, and later dedicated fellowships for women astronomers? Newly founded women’s colleges, especially the Seven Sisters (their very name an allusion to the constellation Pleiades), including Vassar, Smith, Wellesley, Bryn Mawr and Radcliffe, quickly instituted strong traditions in astronomy. Holding aloft the example of Maria Mitchell, discoverer of a comet and professor of astronomy at Vassar, these colleges trained students and provided professorial positions in the subject.
The women employed by the Harvard Observatory increasingly came from such colleges and sometimes returned to them as faculty members. The alumnae of these institutions were loyal, resolute, well-connected and often rich. A succession of wealthy, strong-willed female donors parades across Sobel’s pages, from Anna Palmer Draper, widow of the pioneer stellar spectroscopist and real estate heiress, to New York philanthropist Catherine Wolfe Bruce, to Lydia Hinchman and her fellow members of the Nantucket Maria Mitchell Association. If Harvard’s first doctorate ever in astronomy went to a woman (Payne, a graduate of Newnham College, Cambridge), it was for the simple reason that other women had endowed dedicated research fellowships in astronomy for female college graduates. It is in this sense a very American story, in which money and organisation gave at least some women clout in a society that enshrined both advantages in the booming decades around 1900.
Yet the involvement of women behind the scenes is also a fragment of a much larger and longer story about labour in the astronomical observatory, one somewhat obscured by Sobel’s Harvard focus. Astronomy, like most science before its late 19th-century professionalisation, was a family business. Not only sons (and sons-in-law) but also wives, sisters and daughters were mobilised to help with the tasks of observing, timekeeping, recording, measuring and calculating. Because eyes must remain dark-adapted to observe, but light was required to note exact times and write down sightings, even by the 16th century solitary observation was a romantic myth. Wealthier astronomers such as the Danish nobleman Tycho Brahe could afford to hire assistants (including Johannes Kepler) to monitor the clock and record the values he called out from his perch at the great mural quadrant, but most observatories, including royal ones at Greenwich and Paris, were run as family fiefdoms. Elisabeth Hevelius (wife of the 17th-century Danzig astronomer Johannes Hevelius) and Caroline Herschel (sister of William Herschel and aunt of John Herschel, two of Britain’s most eminent male astronomers) are only the best known of the many women helpmates who made systematic observational astronomy possible from the 16th through the 19th centuries.
Sobel’s book contains many traces (largely unremarked) of the familial blueprint for observatory life, starting with the fact that the director’s personal quarters were on the premises, blurring the boundary between public and private, staff and family. Observatories routinely hired the kith and kin of the director, on both paid and unpaid basis: Selina Cranch Bond, impoverished daughter of Harvard Observatory’s first director (the second was his son), was employed by Pickering as a part-time calculator; William Pickering continued to be employed by his brother as an observer despite his increasingly erratic reports of life on the Moon. Small wonder that the women employed by Harvard Observatory to calculate, measure and classify instinctively reached for family metaphors to describe their community: families, real and ersatz, had long kept astronomy ticking at odd hours, on isolated mountain peaks, and across generations.
Did all this sentimental talk of family mask what was essentially an exploitative situation, in which women were paid wages way below what men with only a fraction of their training and accomplishments would have received? Sobel is defensive here, pointing out that Pickering and Shapley were by the standards of their time champions of women’s achievements in astronomy. These men gave women work, acknowledged their contributions in print, and occasionally advanced their academic careers. But they rarely seem to have granted pay rises, much less a promotion. To be fair, this was not just about sexism: other observatories, such as Oxford and Greenwich, solved their labour problems by hiring schoolboys at similarly low wages, albeit with greater prospect of advancement. The astronomical appetite for cheap labour was insatiable.
It still is. Even in the age of mechanised computation and algorithmic analysis, astrophysicists recruit legions of citizen scientists to help classify the avalanche of data now generated by radio and space telescopes. The motivations of these volunteers are diverse, but not a few echo the views of the women at the Harvard Observatory, who wanted to be part of something much bigger than themselves.
–Guardian News & Media Ltd
