Obama to Shine Light on Unsung Hero of Astronomy

Henrietta Swan Leavitt at Harvard College Observatory
Henrietta Swan Leavitt working at her desk in the Harvard College Observatory. (Image credit: Public domain)

Dig deep in the annals of astronomy and you'd be hard-pressed to find the name of Henrietta Swan Leavitt, a 19th-century astronomer whose ground-breaking insights about a special kind of star led to a cosmic yardstick for measuring the universe.

In 1923, Edwin Hubble used Leavitt's research to discover that a faint, fuzzy patch of light known as Andromeda was not part of the Milky Way, as scientists believed at the time, but instead was a separate galaxy. The universe suddenly became a much bigger place.

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Hubble had found a type of star know as a Cepheid variable, which brightens and fades in a predictable pattern, much like a lighthouse beacon.

But it was Leavitt, toiling away at the Harvard College Observatory more than a decade before Hubble, who realized that a Cepheid's cycle was related to its intrinsic brightness. That insight gave scientists a reliable tool to measure cosmic distances since a Cepheid, like a 100-watt light bulb, would appear to be dimmer the farther away it is.

Leavitt made her discovery from photographs of the Small Magellanic Clouds, though her work was published under the name of her boss, Edward Pickering, a paper presented at a 2004 American Astronomical Society meeting shows.

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"Her assignment at the time was to catalogue stars, not to investigate them. She made this famous and extremely valuable discovery on her own initiative," wrote Pangratios Papacosta, a physics professor at Columbia College in Chicago.

"Hubble's underwhelming acknowledgment of Henrietta Leavitt is an example of the ongoing denial and lack of the professional and public recognition that Henrietta Leavitt suffers from, despite her landmark discovery," Papacosta added

"The vision of the cosmos was dramatically enhanced thanks largely to her discovery, yet no space telescope bears the name Leavitt and no USA postage stamp has been issued to honor her," he wrote.

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More than a century after her ground-breaking work, Leavitt will be acknowledged by the highest office in the United States. President Obama will conclude his week-long stint as guest presenter on Science Presents DNews at 9pm ET/PT by talking about Leavitt's contributions.

Originally published on Discovery News.

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Irene Klotz
Contributing Writer

Irene Klotz is a founding member and long-time contributor to Space.com. She concurrently spent 25 years as a wire service reporter and freelance writer, specializing in space exploration, planetary science, astronomy and the search for life beyond Earth. A graduate of Northwestern University, Irene currently serves as Space Editor for Aviation Week & Space Technology.