The Day We Found the Universe - Marcia Bartusiak [51]
What Slipher and Curtis did not yet know was that a novel way to carry out such a celestial measurement had been budding even as they were beginning their researches on the spiral nebulae. It involved a gifted woman with a keen eye, who came upon some intriguing stars while examining photos of an alluring feature in the southern nighttime sky.
It Is Worthy of Notice
First-time travelers to the southern hemisphere might mistake the clouds for high cirrus formations, somehow made luminous in the dark of night. Ancient Persians called the biggest one Al Bakr, or the White Ox. Europeans were introduced to the “two clouds of mist” from accounts of the first circumnavigation of the globe by Ferdinand Magellan and his crew in the early sixteenth century. And so the hazy pair came to be named in honor of the Portuguese-born explorer. The Large and Small Magellanic Clouds are each a chaotic collection of stars, richly diffused with glowing gas.
Such novel and fascinating sights were a compelling reason for European and American astronomers to set up observatories in the southern hemisphere. The Harvard College Observatory did just that in the 1890s, when it established a southern station in the highlands of Peru, just above the town of Arequipa. Before this, for more than a decade, Harvard had been carrying out a formidable task: to catalog every star in the northern sky and accurately gauge its color and brightness. Presented with a sizable endowment for a program in spectroscopy, observatory director Edward C. Pickering resolved to photograph and classify the spectra of all the bright stars as well. The Peruvian observatory allowed Harvard to extend the reach and sweep of this endeavor to the southern sky. By doing this, Pickering was helping astronomy move beyond just tracking the motions of stars across the sky to figuring out their basic properties. Though tedious and wearying, such astronomical surveys can often reveal a few surprises along the way. The Harvard survey was no exception, but it took many photographs to get there.
The Small and Large Magellanic Clouds (top left, bottom left) as seen from
Cerro-Tololo Inter-American Observatory, in Chile. The Milky Way
is on the right. (Roger Smith/NOAO/AURA/NSF/WIYN)
With the huge number of photographic plates of the northern and southern skies stacking up at the observatory on Garden Street in Cambridge, Massachusetts, Pickering shrewdly recognized the value of smart young women yearning to make contributions in an era that generally denied them full access to scientific institutions. Here was a ready workforce, he noted in one annual observatory report, entirely “capable of doing as much and as good routine work as astronomers who would receive much larger salaries. Three or four times as many assistants can thus be employed, and the work done correspondingly increased for a given expenditure.”
Williamina Fleming (standing) directs her “computers” while
Harvard Observatory director Edward Pickering looks on
(Harvard College Observatory)
These women “computers,” as they were called, many with college degrees in science, were situated in two cozy workrooms, pleasantly decorated with flowered wallpaper and star charts. Working at ma hogany writing tables, crammed together, each woman through the day might peer through a magnifying glass at her selected plate or industriously record her findings in a notebook. Resembling assembly-line workers in a factory, with their plain, unadorned dresses, these dedicated women—swiftly, accurately, and cheaply—numbered each star on a given plate, determined the star's exact position, and assigned it either a spectral class or photographic magnitude. Annie Jump Cannon, who established the stellar classification system adopted internationally in the course of this work, praised Pickering's modern outlook. “He treated [the computers] as equals in the astronomical world,” she