The Day We Found the Universe - Marcia Bartusiak [52]
Pickering's first hire was his housekeeper, Williamina Fleming, who had displayed a keen intelligence in carrying out her duties. Frustrated one day by a male assistant's ineptitude, Pickering had declared that his maid could do a better job, and he found out she could. From the 1880s until Pickering's death in 1919, some forty women came to be employed in “Pickering's harem,” as it was jokingly known. One of his most brilliant choices was Henrietta Leavitt, who first began work at the Harvard Observatory as a volunteer.
Leavitt grew up in Massachusetts, within a big and supportive family (she was the oldest of five surviving children) that cherished education. Her father held a doctorate in divinity from the Andover Theological Seminary. The Leavitts moved to Cleveland when Henrietta was a teenager, where she eventually began her undergraduate studies at Oberlin College. In 1888, at the age of twenty, though, she returned to Massachusetts and entered the Society for the Collegiate Instruction of Women in Cambridge (what later became Radcliffe College). She primarily took courses in the arts and humanities but in her fourth year enrolled in an astronomy course. It must have been an inspiration, because after receiving her certificate in 1892, which stated that she had undertaken an education equivalent to a Harvard bachelor of arts degree, Leavitt remained in Cambridge to take some graduate courses and work as an unpaid helper at the college observatory.
According to those who knew her, she was a serious-minded woman, devoted to her family circle and to her friends. A photograph of her reveals a woman of quiet beauty with soulful eyes. “For light amusements, she appeared to care little,” said Harvard astronomer and colleague Solon Bailey. Yet, he went on, she was still “possessed of a nature so full of sunshine that, to her, all of life became beautiful and full of meaning.” Her good-natured disposition remained even after she experienced, sometime after her graduation, a serious illness that left her severely deaf.
As a volunteer she became an expert in stellar photometry, gauging the magnitude of a star by assessing the size of the spot it imprints upon a photographic plate. The brighter the star, the larger the spot made dark by the star's light upon the negative. In carrying out this work, she was also instructed to keep an eye out for variable stars, stars that regularly increase and decrease in brightness over a fixed span of time. These variables were found by comparing photographs of the same region of the sky taken at different times. Leavitt would place the negative of a photograph taken on one date directly over a positive photograph of the same region of the sky taken on another date. If the black and white images of a star did not exactly match, the star was likely changing its intensity and so was suspected to be a variable.
Henrietta Leavitt at her Harvard College Observatory desk
(AIP Emilio Segrè Visual Archives)
After writing up a draft of her initial research, Leavitt left Harvard in 1896 for a while, first traveling through Europe for two years and then moving to Wisconsin, where her father had a new ministry. But in 1902 she wrote Pickering for information on new job opportunities, at either Harvard or elsewhere. She obviously wanted to get back into astronomy and must have been overjoyed when Pickering made her an offer within three days for full-time employment. “For this I should be willing to pay thirty cents an hour in view of the quality of your work, although our usual price, in such cases, is twenty five cents an hour,” he wrote her. She replied that it was a “very liberal offer,” what today (taking inflation into account) would be a little over the U.S. minimum wage. A man would have gotten nearly twice that.
Not until the spring of 1904, though, did variable stars come back into her life in full force.