Lamp · table · mirror — her eclipse model, c. 1790s
Wang Zhenyi
王貞儀
1768 — 1797
A table, a lamp, a mirror — and the moon's darkening explained. She was not yet twenty-five.
In a garden pavilion in Jiangning — the city we now call Nanjing — a young woman set a round table in the middle of the floor. From the ceiling beam she hung a crystal lamp on a cord. On one side of the table she stood a round mirror. Then she walked the three objects through their true motions, sun and earth and moon, until the shadow fell exactly where it should. Wang Zhenyi was reasoning out, from first principles and a room's worth of furniture, why the moon goes dark — and her account of it matches what astronomers say today.
She was almost entirely self-taught, in a subject Qing China thought unfit for women to study at all: calendrical astronomy, the mathematics of the heavens. She read her dead grandfather's library beyond the Great Wall, learned archery from a general's wife, argued that Chinese, Islamic and European methods should be judged by accuracy rather than origin, and refuted the ancient picture of a flat earth under a round sky. She lived twenty-nine years. Dying of malaria, she went through her own manuscripts and destroyed most of them, keeping only the fraction she judged worth surviving her. About ten of her scientific essays remain. They were enough.
Twenty-nine years
The lifeline
1768
Born in Jiangning (Nanjing). Grandfather teaches her astronomy; grandmother, poetry; father, medicine and mathematics
1782
Her grandfather Wang Zhefu dies. The family travels beyond the Great Wall to mourn — and she reads his book collection for four years
1784
At sixteen she crosses south of the Yangtze with her father; travels through Beijing, Shaanxi, Hubei, Guangdong, Anhui
1786
At eighteen, back in Jiangning among women scholars, she turns to astronomy and mathematics — self-taught
1793
Marries Zhan Mei of Xuancheng, Anhui, at twenty-five; keeps writing, and takes on male students
1797
Dies at twenty-nine after a relapse of malaria, having destroyed most of her own papers
By the numbers
The measure of her
29
Years she lived — 1768 to 1797, and no children to keep her name
13
Volumes of poems, prose, prefaces and postscripts she left behind
~25%
Of her own writings she kept while dying — 20–30 per cent; the rest she destroyed
1994
The year the IAU named a crater on Venus for her — 197 years after her death
What she worked out
The work
c. 1790s
Explanation of Lunar Eclipses. The table-lamp-mirror model, plus a synthesis of astronomers from Yu Xi to Guo Shoujing set against Islamic, European and contemporary calendars. Her explanation of the cause of eclipses holds up.
c. 1790s
Dispute of the Procession of the Equinoxes. How the equinoxes shift and how to compute the shift — with notes on the number of stars, the direction of travel of the sun, moon, Mercury, Venus, Mars, Jupiter and Saturn, and the relation between lunar and solar eclipses.
c. 1790s
Theory of the Earth's Roundness. She rejected the thousand-year-old flat-earth-under-round-heaven picture, treating up and down as relative to where the observer happens to stand.
1792
The Simple Principles of Calculation, written at twenty-four — after she had already rewritten Mei Wending's Principles of Calculation in plainer language, simplifying multiplication and division for beginners.
undated
The Explanation of the Pythagorean Theorem and Trigonometry, on foundational geometry — one of roughly ten of her scientific papers to survive at all.
Dismissed, then named in the sky
Recognition
In her lifetime
No post, academy or observatory in Qing China was open to a woman
Calendrical astronomy was held improper for women to study
Contemporaries — family members among them — questioned or dismissed her scientific work
Even the praise stung: the poet Yuan Mei said her verse had "the flavour of a great pen, not of a female poet"
She published little; most of her scientific writing is lost
Afterwards
Qian Yiji, who compiled her Simple Principles of Calculation, called her "the number one female scholar after Ban Zhao"
Her biography stands in the official history of the Qing dynasty
A crater on Venus carries her name — approved by the IAU in 1994
So does main-belt asteroid 43259 Wangzhenyi, found in 2000
The place that made her
Jiangning
Her family's roots were in Anhui; her grandfather moved the household to Jiangning, the great southern city of books. It was her grandfather's collection that taught her the sky, her grandmother's ear that taught her verse, and her father — who failed the imperial examinations, turned to medicine, and recorded his prescriptions in a four-volume collection — who taught her mathematics and geography. When she returned to Jiangning at eighteen she found other women scholars there, and began to write in earnest.
4 yrs
Spent beyond the Great Wall after 1782, reading her grandfather's books
5
Regions she travelled before twenty-five: Beijing, Shaanxi, Hubei, Guangdong, Anhui
18
Her age when she turned, back home, to astronomy and mathematics
"It's made to believe / Women are the same as Men; / Are you not convinced / Daughters can also be heroic?"
— Wang Zhenyi 始信須眉等巾幗，誰言兒女不英雄