Ele Willoughby, PhD

For Day 21 of @spacetober_challenge #spacetober_challenge prompt star: trailblazing US #astronomer Annie Jump Cannon (1863 – 1941), here with her stellar classification system which sorted stars based on spectral types, revealing their temperature from hot blue to cool red stars: O,B,A, F, G, K & M. Named the Harvard Classification after the university, her tremendous contribution was less visible. 🧵1/

#printmaking #womenInSTEM #histsci #DisabledInSTEM #linocut #mastoArt

Oct 21, 2025 at 11:24amWeb
Show threadEle Willoughby, PhDOct 21, 2025
Eldest of 3 daughters of Delaware shipbuilder/state senator Wilson Cannon & Mary Jump, Annie’s mom taught her the constellations & encouraged her to pursue her own interests. She studied physics with Sarah Frances Whiting, 1 of few US women #physicists at the time, at Wellesley & became valedictorian in 1884. She returned home, worked various jobs, & published her photos over next decade. She lost most of her hearing possibly due to scarlet fever. 🧵2/
Show threadEle Willoughby, PhDOct 21, 2025
When her mom died in 1894 she needed to escape her grief. She wrote Whiting & was hired as junior physics teacher, which allowed her to take grad #physics & #astronomy classes. Harvard astronomer Pickering hired her as assistant in 1896. Running a program to map & catalogue every visible star to photographic magnitude 9, he hired women (whom he could pay as little as 25 cents/hr for 7 hr/day, 6 days/week) known as Harvard Computers to work on data & catalogue photos. 🧵3/
Show threadEle Willoughby, PhDOct 21, 2025

In her first 3 years, she classified 1000 stars. By 1911 she was Curator of Astronomical Photographs & by 1913 she could accurately classify 200 stars/hour! She published her 1st star catalogue in 1901 & finished her MSc at Wellesley in 1907.

Antonia Maury insisted on a complex categorization scheme, to the dismay of manager Williamina Fleming. Cannon negotiated a compromise, dividing stars into spectral classes based on Balmer absorption lines of hydrogen. 🧵4/5

Show threadEle Willoughby, PhDOct 21, 2025

Nicknamed “Census Taker of the Sky,” she catalogued ~350,000 stars, more than anyone & discovered 300 variable stars, 5 novas & 1 spectroscopic binary.

In 1922, International Astronomical Union formally adopted Cannon’s classification system. She received many honours & awards before becoming William C. Bond Astronomer at Harvard in 1938.

https://minouette.etsy.com/listing/1670899819

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