1. He was a college dropout.
Galileo, whose father was a lute player and music theorist, was born in Pisa, Italy. Although his father was from a noble family, they weren’t wealthy. As a preteen, Galileo began studying at a monastery near Florence and considered becoming a monk; however, his father wasn’t in favor of his son pursuing a religious life and eventually removed him from the school. When he was 16, Galileo enrolled at the University of Pisa to study medicine, at his father’s urging. Instead, though, he became interested in mathematics and shifted his focus to that subject. Galileo left the school in 1585 without earning a degree. He continued his mathematics studies on his own and earned money by giving private lessons before returning to the University of Pisa in 1589 to teach math.
2. He didn’t invent the telescope.
Galileo didn’t invent the telescope—Dutch eyeglass maker Hans Lippershey is generally credited with its creation—but he was the first person to use the optical instrument to systematically study the heavens. Lippershey’s patent application for the device in 1608 is the earliest on record; however, because the Dutch government decided the telescope was too easy to copy and because another Dutch instrument-maker had tried to patent the device a short time after Lippershey, no patent was granted. In 1609, Galileo learned about the device and developed one of his own, significantly improving its design. That fall, he pointed it at the moon and discovered it had craters and mountains, debunking the common belief that the moon’s surface was smooth.
Galileo soon went on to make other findings with his telescope, including that there were four moons orbiting Jupiter and that Venus went through a complete set of phases (indicating the planet traveled around the sun). Galileo’s discoveries brought him acclaim and in 1610 he was named the chief mathematician and philosopher to the grand duke of Tuscany as well as chief mathematician at the University of Pisa. More significantly, Galileo’s observations would lead him to support the theory, laid out in 1543 by Polish mathematician and astronomer Nicolaus Copernicus, that the sun is the center of the universe and the Earth and other planets revolve around it.
3. His daughters were nuns.
Galileo had three children with a woman named Marina Gamba, who he never married. In 1613, he placed his two daughters, Virginia, born in 1600, and Livia, born in 1601, in a convent near Florence, where they remained for the rest of their lives, despite their father’s eventual troubles with the Catholic Church. Galileo maintained close ties with his older daughter, who became known as Sister Maria Celeste. From inside the convent, she baked and sewed for him, among other tasks. He in turn gave food and supplies to the impoverished convent. Galileo’s son, Vincenzo, born in 1606, studied medicine at the University of Pisa, married well and resided in Florence as an adult.
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4. Galileo was sentenced to life in prison by the Roman Inquisition.
Copernicus’ heliocentric theory about the way the universe works challenged the widely accepted belief, espoused by the astronomer Ptolemy in the second century, that put the Earth at the center of the solar system. In 1616, the Catholic Church declared Copernican theory heretical because it was viewed as contradicting certain Bible verses. Galileo received permission from the Church to continue investigating Copernicus’ ideas, as long as he didn’t hold or defend them. In 1632, he published “Dialogue of the Two Principal Systems of the World,” and although it was presented as a discussion between friends about the ideas of Ptolemy and Copernicus, the book was seen as supporting the Copernican model of the universe. As a result, the following year Galileo was ordered to stand trial before the Inquisition in Rome. After being found guilty of heresy, Galileo was forced to publicly repent and sentenced to life in prison.
5. He spent his final years under house arrest.
Although Galileo was given life behind bars, his sentence soon was changed to house arrest. He lived out his final years at Villa Il Gioiello (“the Jewel”), his home in the town of Arcetri, near Florence. Barred from seeing friends or publishing books, he nonetheless received visitors from around Europe, including philosopher Thomas Hobbes and poet John Milton. Additionally, he managed to smuggle out the manuscript for a new work, “Discourses and Mathematical Demonstrations Concerning Two New Sciences,” about physics and mechanics. The book, Galileo’s last, was published in Holland in 1638. That same year, Galileo went totally blind. He died on January 8, 1642, at age 77.
6. His middle finger is on display in a museum.
After Galileo died, he was buried in a side chapel at the church of Santa Croce in Florence. Nearly a century later, in 1737, as the scientist’s remains were being transferred to a burial place of honor in the Santa Croce basilica three of his fingers, along with a vertebra and a tooth, were removed from his corpse. Two of Galileo’s fingers, along with his tooth, were kept by one of his admirers and handed down through generations of his relatives. The items were thought to be lost sometime in the early 1900s. However, in 2009, the two fingers and tooth appeared at an auction and were snapped up by a private collector; using historical documentation, experts later concluded the items were Galileo’s. Meanwhile, the third finger taken from Galileo’s remains—the middle finger of his right hand—has been housed at various museums in Italy since at least the first half of the 1800s. The purloined vertebra ended up at the University of Padua, where Galileo taught from 1592 to 1610.
7. NASA named a spacecraft for him.
In 1989, NASA and a team from Germany launched a spacecraft bearing Galileo’s name from the cargo bay of space shuttle Atlantis. After arriving at Jupiter in 1995, the Galileo spacecraft became the first to study the planet and its moons for an extended time. The spacecraft found evidence of saltwater below the surface of three of Jupiter’s moons, Europa, Callisto and Ganymede, and provided information about volcanic activity on another one of the planet’s moons, Io. (The four moons were discovered by the real-life Galileo in 1610 with a telescope.) In 2003, the mission came to an end when NASA intentionally crashed the spacecraft into Jupiter (the solar system’s largest planet) in order to eliminate the risk of Galileo colliding with Europa and contaminating any potential life there.
8. The Vatican didn’t admit Galileo was right until 1992.
In 1979, Pope John Paul II initiated an investigation into the Catholic Church’s condemnation of Galileo. Thirteen years later, and 359 years after Galileo was tried by the Inquisition, the pope officially closed the investigation and issued a formal apology in the case, acknowledging that errors were made by the judges during the trial.