Harvard College Observatory: Edward Pickering, 1

Edward Charles Pickering was born in Boston on July 19, 1846 into a patrician family. Upon graduating from the Lawrence Scientific School of Harvard University at the age of 19, and after a stint as a mathematics instructor at his alma mater, he was hired in 1867 by the Massachusetts Institute of Technology as a professor of physics. During the following decade, Pickering developed MIT’s Physical Laboratory, the first such establishment in the US.¹

The way the laboratory was set up and administered reflected Pickering’s credo: “There are no secrets in Science.” The laboratory was open not only to students and teachers of physics but also to the lay public wishing to carry out their research. In 1876, Pickering was appointed by Harvard President Charles Eliot as the fourth director of the Harvard College Observatory.

Pickering entered his duties at the observatory in 1877 with a plan to investigate the brightness of stars by photometry. In 1882, he extended traditional photometric techniques by launching a program in photographic astronomy. This innovation was based on dry photographic plates: glass plates coated with a gelatin emulsion of silver bromide that could be stored before exposure and developed at leisure after exposure.

In 1886, Pickering launched the Henry Draper Memorial project of spectrally resolved photographic mapping of both the northern and southern skies. The telescopes used entailed a dispersive element, an ocular prism in this case, in order to spectrally resolve the star images, recorded as structured smudges on the photographic glass plates. Pickering’s predilection for spectroscopy likely originated in his training as a physicist. The spectrally resolved astrophotography enabled an unprecedented accumulation of empirical data intended to prepare the soil for a better understanding of the nature of stars.

Moreover, given that the astrophotographs were taken at known times—the exposures lasted minutes to tens of minutes—a set of subsequent astrophotographs contained information about the variation in time of the stars’ brightness and spectra. As a result, the study of variable stars became a major preoccupation of the astrophysical community. Enhanced sensitivity to time variation was achieved by the technique of superposing a negative and a positive taken at different times, leading to the discovery of almost 3,500 variables at the observatory during Pickering’s tenure.

References

1. Edward C. Pickering, “Plan of the Physical Laboratory of the Massachusetts Institute of Technology,” (A. A. Kingman, 1869), Museum of the Boston Society of Natural History.
2. Annie J. Cannon, “Edward Charles Pickering,” Popular Astronomy, 27, 1919, 177–182.

Cite this resource

Bretislav Friedrich and Maria McEachern, “Edward Pickering, 1,” Harvard College Observatory history guide, American Institute of Physics, 2026,

Note that this material was originally developed in concert with the Williamina Fleming history guide as part of the Women in the History of Quantum Physics collection.