522: Miss Leavitt’s Stars by George Johnson
522.0904: Johnson, George. Miss Leavitt’s Stars: The Untold Story of the Forgotten Woman Who Discovered How to Measure the Universe. New York: Atlas, Books, 2005. 130 pp. ISBN 0-393-05128-5.
- 500: Science
- 520: Astronomy and allied sciences
- 522: Techniques, procedures, apparatus, equipment, and materials
- +0904: 20th Century
In the early days of the 20th century, astronomy was tedious and manual. To understand what was out in the heavens, scientists used photographic plates attached to telescopes, exposed them to the night sky, and then pored over the resulting images to catalog new stars and nebulae. The sadder part of this endeavor is that the cataloging of celestial bodies on photo plates was seen as menial labor and left for groups of “human computers” to do. These groups usually consisted of brilliant women who were terrific at mathematics and physics, but were hired for dimes on the dollar simply because of their gender. George Johnson’s Miss Leavitt’s Stars is the tale of one computer who went on make a revolutionary discovery that changed the way we view the universe.
Henrietta Swan Leavitt was born on Independence Day, 1868. She was most likely a precocious child, and went on to attend Oberlin College and later Radcliffe to get her degree. She became interested in astronomy and went to work for Edward Pickering at the Harvard College Observatory to study variable stars. The stars were called variable for the simple reason that their brightness changed over time. After fifteen years and working through the images for over 1,700 stars, she made a simple but startling discovery. The intensity of a star’s brightness was directly related to how long the star stayed bright. Using this information about variable stars, or Cepheids, she was able to determine their distance from Earth, and from there, the distance of other galaxies from Earth. These measurements lead directly to the discovery that the universe is expanding from a some central point that wasn’t the Milky Way, giving credence to what we now call the Big Bang Theory.
Johnson’s little book on such a big discovery was fun and enlightening (if you’ll pardon the pun). There’s not a lot of background information on Leavitt, so the biography here is thin. Johnson supplements that with the history of astronomical photography, the story of Edward Pickering (and his harem of human computers), and the ramifications of Leavitt’s discovery. It’s one of the great shames of history that she died before she could be formally nominated for the Nobel Prize that she so richly deserved, but those that benefitted from her research were always keen to credit her work accordingly. A quick and informative read.