Galileo's Daughter

Galileo’s Daughter: A Historical Memoir of Science, Faith, and Love is a 1999 nonfiction book by Dava Sobel. It details the relationship between Renaissance scientist Galileo and his daughter Suor Maria Celeste, a nun. Sobel, a well-known science writer, based the book on Maria Celeste’s 124 surviving letters; Galileo’s are lost to history. His daughter’s letters, and the book, display her sharp mind, hard work, and love for her publicly disgraced father. Her letters also offer a glimpse of who Galileo was on a personal level.

Sobel offers necessary context on Maria Celeste. Born Virginia Galilei in 1600, she and her siblings were all illegitimate. As such, the girls’ marriage prospects were poor, and so Virginia and her sister joined the San Matteo convent in Arcetri, Italy, in their adolescence. Virginia took the veil and became a nun at age 16, and adopted the name Suor Maria Celeste at that time. Her letters were her only means of contact with her father from within the convent. She spent the rest of her life living simply and in seclusion.

Maria Celeste’s letters are written fondly, using elaborate and flattering titles to address her father that show her love for him. The letters were not only a means of keeping in touch with him, but for learning news of the outside world and the scientific discoveries—and upheavals—her father was making. He had already begun his experiments during Maria Celeste’s early years. In 1609, he performed one of his first experiments with his telescope from a garden in Padua. In 1610, he was granted an appointment as the chief mathematician and philosopher to the Grand Duke of Tuscany. But in 1616, the same year Maria Celeste took her vows, a Cardinal Inquisitor and the Pope himself formally rebuked Galileo and warned him to stop studying the heavens. His discoveries, they said, were close to becoming heretical.



Sobel backtracks to discuss Galileo’s career and history of scientific experimentation. Sometime around 1591, he conducted his famous Leaning Tower of Pisa experiment, intended to disprove Aristotle’s theory that two objects of different weights would reach the ground at different times if dropped from a height. He discovered that the two disparate objects he dropped from the tower fell at the same rate of speed, despite their different weights, disproving the idea that heavier objects fall faster than lighter ones.

Galileo’s earlier career highlights include the invention of a geometric compass and tutoring Cosimo Medici, son of Grand Duke Ferdinand, in math. He developed a strong friendship with Cosimo that lasted throughout both their lives. He continued to teach in Padua, inventing his first version of the telescope there. He shared his inventions in travels across Italy so that others might glimpse a clearer view of the night sky and its stars and planets. At first, he enjoyed honors and accolades for his work, garnering an invitation to the prestigious Lyncean Academy, the first scientific society. He established a strong reputation and fame as a scientist.

But soon, as Sobel writes, that fame turned to infamy. His studies and observations in astronomy led him towards a Copernican view of the universe: one in which the Sun, not the Earth, is the center of the solar system, and that Earth revolves around the Sun rather than the other way around. This was counter to Aristotle and Ptolemy’s understanding of the solar system, and against the Church’s official stance on the matter.
Galileo wanted to publish a book, Dialogue of the Chief World Systems, describing his observations and new understanding of the solar system, but to do so he needed a literal stamp of approval from a religious authority. Sobel explains that this approval was required for all books published in Italy during the time period. He did get the book published, but its contents were denounced by the Roman Inquisition soon afterwards. Galileo faced Inquisitorial hearings for his work, and in the end the Inquisition condemned the book for violating the conditions required to publish and for insisting that the heliocentric Copernican model of the universe was fact rather than hypothesis. The Inquisition called heliocentrism “foolish and absurd,” as well as a contradiction of Holy Scripture.



The Inquisition found Galileo himself “suspect of heresy” and forced him to recant his theories. He was placed under house arrest for the rest of his life and ordered never to study or teach his astronomical theories again. He obeyed the letter of this order, but did continue to research matters indirectly related to his previous theories. In another few decades, the Ptolemaic model lost its credibility, and astronomers began to look for alternative ways to understand the solar system and the universe as a whole.

Only a year after the publication of Galileo’s work, Mary Celeste died in the convent. Galileo outlived her for another eight years, leaving a strong scientific legacy behind. Sobel describes his other scientific achievements, including the discovery of sunspots and his post-house arrest studies that set the stage for Isaac Newton’s three laws of motion developed in the late 17th century. He also helped to develop the scientific method of conducting research, paving the way for centuries of scientific experiments and discoveries ahead.

The book documents Galileo through his daughter’s eyes. She demonstrated a great interest in her father’s work and did not hesitate to offer her own opinions on his work. The letters also offer a glimpse into the famous astronomer on a personal level, discussing the everyday details of his life.



The book received positive reviews upon release for Sobel’s work in translating Maria Celeste’s letters into English for the first time. It received a starred review from Publisher’s Weekly, which noted the deft way Sobel used the letters to flesh out her narrative, including an element of “faith and piety often missing in other retellings of Galileo’s story.” Galileo’s Daughter was nominated for the 2000 Pulitzer Prize for Biography or Autobiography.