Among his other accomplishments, Galileo Galilee had three children out of wedlock. His son was eventually "legitimized" by the Grand Duke of Tuscany; the daughters, probably unmarriageable due to their illegitimacy, became nuns in the convent of San Matteo in Arcetri, a town that was basically a suburb of Florence, Italy. Despite the situation, Galileo was a devoted father and kept in touch with his children, eventually living in a villa around the corner from San Matteo. His eldest daughter was called Virginia but changed to Maria Celeste when she took her vows. The name was a tribute to Galileo's celebrity as an astronomer. He had improved the telescope and used it to discover moons around Jupiter and spots on the sun. As his career took off, he corresponded with Maria, who wrote as often as twice a week. She was well-educated, hard-working, and intelligent. She ran the apothecary at the convent, so she was able to make pills and other medicines for the nuns and for Galileo's various aliments. She also managed his Arcetri home when he was out of town.
He was out of town for quite a long time because he ran afoul of the the Holy Office. He published his Dialogue Concerning the Two Chief World Systems, which the pope found offensive. The dialogue represents the pope's position with the naive Simplicio, who comes off rather badly. The controversy is covered in detail with the typical modern bias in favor of Galileo, though the author is more even-handed than many contemporary pro-Galileo accounts. The book focuses on the relationship with Maria Celeste, providing some insight into convent life in the 1600s, which isn't as cut off from the world as one might expect. Unfortunately, after Maria Celeste died the mother superior was concerned about controversy and destroyed Galileo's letters, so the book quotes only the letters Galileo received from his daughter. The author has plenty of other sources to draw upon, so the story is not half-missing.
The book is entertainingly written and gives a very human face to both Galileo and his daughter. The book tells Galileo's life story with a special emphasis on his relationship with his daughter. As such, those opposed to Galileo are often given short shrift, which I found a bit unsatisfying. I'd be interested in reading a book that gives both sides of the controversy their due. This isn't that book but is still well worth reading.