One of Harvard College Observatory's photographic plates. [Image credit: Jenny Woodman]

Edward Charles Pickering was a leading light of 19th century astronomy, his modern approach to astronomy earning Harvard College Observatory an international reputation. Pickering's honors included twice receiving the Gold Medal of the Royal Astronomical Society of Britain.

Learner and teacher
Edward Pickering was born in Boston on July 19, 1846 to a prominent New England family. He had a younger brother William who also an astronomer.

Pickering graduated from Harvard, aged 19, with highest honors. Following a time as an instructor at Harvard, he taught physics at the Massachusetts Institute of Technology (MIT). In 1868 he was appointed MIT's Thayer Professor of Physics. MIT's founder William Barton Rogers had wanted a physics teaching laboratory, and Pickering was the one who made it happen. It was the first of its kind in the USA, and Pickering's involving students in experimental work revolutionized physics teaching.

Wellesley College's physics professor Sarah Whiting was allowed to attend Pickering's lectures, and he invited her to observe spectroscopy and other new techniques in astronomy. Whiting then set up an instructional physics lab at Wellesley, and established a course in practical astronomy.

In 1877, aged 31, Pickering was made director of Harvard College Observatory – a controversial appointment since he wasn't an astronomer. However he was a physicist, and had shown himself to be a first-class administrator.

Astrophysics
Pickering's appointment was part of a new astronomy that emphasized astrophysics, the science behind astronomy. Although traditionalists opposed it, from the start Pickering was keen to use photography, especially to record the spectra of stars.

Dedicated to the pursuit of science, Pickering had a vision for the observatory. It was to pursue research that wasn't being done elsewhere. Photometry – the measurement of light – was a neglected area, but one in which Pickering already had expertise. Estimating the brightness of stars by eye meant that there was no measurable standard scale. He set out to devise a standard and to compare the magnitudes of stars to it.

From 1879-1882 he measured over four thousand stars using a photometer that he had designed. In 1886 the Royal Astronomical Society awarded him their Gold Medal for this work.

Williamina Fleming
Legend has it that when Pickering got fed up with his assistant, he announced that his housekeeper could do better. This seems somewhat unlikely from a man described as a “true Victorian gentleman”. Nonetheless in 1881 Pickering did hire Williamina Fleming to work in the observatory. Despite lacking a background in science or math, she obviously impressed her employer with her general competence and intelligence.

The Draper legacy
In 1882 the death of Henry Draper, physician and astrophotographer, was a sad event. Yet it turned out to be key to the success of Harvard College Observatory and a step forward for women in astronomy.

Draper had begun a catalog of stellar spectra, but his early death seemed likely to end the project. However in 1885 his widow Anna decided the catalog should be completed. She offered his telescopes and funding to Harvard for Pickering to do the work.

Fleming took charge of the Henry Draper project, and in 1890 the Draper Catalogue of Stellar Spectra was published. Primarily Fleming's work, it included the spectral classifications of over ten thousand stars. When Pickering wanted to extend the work by adding the spectra of southern hemisphere stars, Anna Draper agreed to fund the establishment of a telescope in Peru.

The Draper project would outlive Anna Draper and Edward Pickering and Williamina Fleming. Annie Cannon, Sarah Whiting's former student, joined the team in 1896, and she classified over a quarter of a million spectra from the southern telescope. After Pickering's death in 1919, she oversaw the continued publication of the Henry Draper Catalogue which remains a useful resource. Many stars are still known by their HD numbers.

The computers
In the days before electronics, computers were people that did an observatory's calculations and data processing. Traditionally, they were men. But Edward Pickering realized two things: (1) women were competent; and (2) women were cheaper.

When the Draper Project came along, many more computers were needed. They were responsible for cataloging, indexing, examining and caring for the new photographic plates, identifying the stars on them and then calculating their positions. The work was demanding and repetitive, and women's pay was half that of men. In Pickering's utilitarian view, he needed computers and if he could get twice as many for the price, he was going to do it.

On the one hand, Pickering could be criticized for exploiting the women. Yet he did hire women, which wasn't the case elsewhere. Pickering treated his staff with respect, while others referred to the women computers, derisively, as “Pickering's harem”, even when Annie Cannon, Henrietta Leavitt and others were known for their original work.

A job well done
Harvard College Observatory built a reference collection of stellar spectra that was a resource for astronomers worldwide. Pickering's hard work and organizational skills led the way to the data sets and big projects of modern science. He was also active in promoting astronomy to the public.

Pickering died in Cambridge on February 3, 1919. Although now he's scarcely known except for hiring the women computers, in his day, his work was lauded internationally. The Astronomical Society of the Pacific gave him the prestigious Bruce Medal for lifetime achievement in astronomy. Learned academies in the USA and France, as well as the German government, bestowed honors on him.