Unforgotten sisters: The woman who bested Kepler


In the second of a three-part series, Italian science writer Gabriella Bernardi profiles seventeenth century astronomer Maria Cunitz. 


A memorial to Maria Cunitz, 18th century female astronomer and author of Urania propitia, in front of entrance to Early Commerce Museum in Ratusz, Poland.
A memorial to Maria Cunitz, 18th century female astronomer and author of Urania propitia, in front of entrance to Early Commerce Museum in Ratusz, Poland.
Wikimedia Commons

She was able to hold a conversation in seven languages: German, Italian, French, Polish, Latin, Greek and Hebrew. She was also a skilled musician and painter and enjoyed astronomical problems – a talent which drove the French astronomer Jean-Baptiste Delambre to compare her to Hypatia, the famous Alexandrine philosopher of antiquity.

The name of this extraordinary woman was Maria Cunitz. Unfortunately, we have no portrait of her, but she left us a book, Urania Propitia, the first astronomical book signed by a woman in the modern era, written when women were denied access to university in any form.

She was born in 1610, in Schweidnitz or, according to some more recent sources, in Wohlau, and died at Pitschen, 54 years later. All of these cities are located in Silesia, a region of central Europe that today is almost entirely in Poland, just above the Czech Republic. At that time, however, it was under the domain of the German mercantile Augsburg dynasty.

Maria was the eldest daughter of Heinrich Cunitz, a wealthy doctor and landowner of the region, an open-minded person who educated his offspring in many subjects, including languages, painting, music, poetry, mathematics, medicine and history. At the age of 13 Maria got married for the first time. Today that seems like a very young age, but it was not unusual at the time.

Her husband died three years later, and in 1630 she married Elie de Loewn. It was a decisive event, because her new husband was a physician, but also an amateur astronomer who encouraged her astronomical studies. Even since before their marriage they had shared a passion for the subject. For example, together they observed Venus in December 1627 and Jupiter in April 1628, but de Loewn, much older than Maria, proved particularly important for introducing her to professionals in the field.

She corresponded with prominent scientists, including the famous astronomer Johannes Hevelius of Danzig, and Pierre Gassendi, secretary to the Queen of Poland. She always wrote in her husband’s name, and received the replies addressed to him. The conventions of the time made it inappropriate for a woman to exchange letters with a scholar.

Her career was also influenced by her means. Indeed, Maria was certainly able to carry on a program of astronomical observations, but she could not afford the instruments needed to become competitive in this field. So, she concentrated on mathematical calculations. In particular, Maria knew of German astronomer Johannes Kepler’s research results, including his Tabulae Rudolphinae – the calculations of planetary positions, or ephemerides, performed by Kepler from Tycho Brahe’s observations. Eventually she decided to prepare her own version.

The importance of this resolution should not be underestimated. Kepler’s work, published in 1628, outlined the heliocentric theory. This, plus his proposed new laws based on the elliptical shape of planetary orbits, comprised two of the most innovative scientific topics of the seventeenth century. Maria Cunitz, thus, was riding the wave at the forefront of modern astronomy, along with many other scientists of that period.

At the same time, her work distinguished her from the others because she attempted to obtain comparable results using algorithms that were considerably simpler, and easier to calculate, than the ones Kepler deployed. In an epoch when no computational aid was available, this constituted a true and original research program about one of the most advanced scientific topics.

The fact that this job was conducted among the difficulties of the Thirty Years War, which raged from 1618 to 1648, lends even more prestige to her work. Because of the war, Maria and her family took refuge in a Cistercian convent. She was finally able to publish her results in 1650.

It was printed at her own expense, with the quite long Latin title: URANIA PROPITIA SIVE Tabulae Astronomicae mirè faciles, vim hypothesium physicarum à Kepplero proditarum complexae; facillimo calculandi compendio, sine ulla Logarithmorum mentione, phaenomenis satisfacientes. Quarum usum pro tempore praesente, exacto, & futuro, (accedente insuper facillimá Superiorum SATURN & JOVIS ad exactiorem & coelo satis consonam rationem, reductione) duplici idiomate, Latino & vernaculo succinctè praescriptum cum Artis Cultoribus communicat MARIA CUNITIA. She dedicated the book to Emperor Ferdinand III, but the publication has another remarkable trait. It is written both in Latin and in German, and today is credited as contributing to the development of modern scientific German language.

Maria’s work was not exempt from criticism, but that was probably unavoidable. Admittedly, she made some computational errors, and others had been introduced by her simplified algorithms. On the other hand, none of the contemporary tables from other scientists were void of errors, and she also corrected several made by Kepler in his work. In the end, the accuracy of her ephemerides was in many cases better than the ones offered by Kepler.

Nowadays, with just nine copies left in the world, Urania Propitia is considered a rare text. One of these was recently purchased for the library of the University of Florida, in the US. The university justified the acquisition because as “an important addition to the libraries because it celebrates the university’s commitments to women’s studies, history of science, astronomy, and the printed word as the prime means of communication for more than five hundred years.”

It is curious to note that somebody turned Maria Cunitz’s remarkable achievements into a point of criticism. In 1727 Johan Kaspar Elberti, in giving details of her life in his book Educated Silesian Women and Female Poets, wrote: “[Maria Cunitz] was so deeply engaged in astronomical speculation that she neglected her household. The daylight hours she spent, for the most part, in bed (concerning which all manner of ridiculous events have been reported) because she had tired herself from watching the stars at night.”


Gabriella Bernardi is a science journalist and author based in Turin, Italy. Her two most recent books are Giovanni Domenico Cassini: A Modern Astronomer in the 17th Century (Springer, 2017), and The Unforgotten Sisters: Female Astronomers and Scientists before Caroline Herschel (Springer, 2016), on which this story is based.

Gabriella bernardi.jpg?ixlib=rails 2.1
Gabriella Bernardi is a science journalist and author based in Turin, Italy. Her two most recent books are Giovanni Domenico Cassini: A Modern Astronomer in the 17th Century (Springer, 2017), and The Unforgotten Sisters: Female Astronomers and Scientists before Caroline Herschel (Springer, 2016).
  1. https://www.britannica.com/biography/Jean-Baptiste-Joseph-Delambre
  2. https://www.smithsonianmag.com/history/hypatia-ancient-alexandrias-great-female-scholar-10942888/
  3. https://en.wikipedia.org/wiki/Johannes_Hevelius
  4. https://plato.stanford.edu/entries/gassendi/
  5. https://cosmosmagazine.com/space/johannes-kepler-s-obsession-with-mars
  6. http://www.springer.com/it/book/9783319634678
  7. http://www.springer.com/it/book/9783319261256
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