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Galileo Galilei, sometimes misspelled as Galileo Galiley, was an Italian mathematician, physicist, philosopher, engineer, and astronomer. He is referred to as the “Father of Science” and the “Father of Modern Physics” for his extensive contributions to the 17th-century scientific revolution. He advocated for the heliocentric and Copernican views of the universe which led to his investigation, arrest, and trial by the 1615 Roman Inquisition.

Youth and Education

Galileo Galilei, not Galiley, was born in 1564 in Pisa and baptized in the Cathedral of Pisa.[1] He was the first born child of Vincenzo Galilei, a music theorist, composer, ad famous lutenist, and Giulia Ammannati. His father taught him the lute, the value of measurable experimentation, a love of rhythm and music, and a healthy suspicion of authority.[2] The family moved to Florence in 1574 and Galileo joined them two years later, after spending time with Jacopo Borghini.

Galileo then began studying at the Monastery of Santa Maria di Vallombrosa.[3] His experience made him consider joining the priesthood, but instead followed the advice of his father and enrolled in the medical program at the University of Pisa.[4] His love of physics won in the end and after geometry lecture, he convinced his father to let him study mathematics and natural philosophy.[5]

Biography of Galileo Galilei and His Scientific Career

In 1588, Galileo began teaching chiaroscuro and perspective in Florence at the Accademia delle Arti del Disegno.[6] The University of Pisa appointed him the Chair of Mathematics in 1589.

Galileo then became the sole caregiver for his younger brother Michelagnolo when his father died in 1591. He moved to the University of Padua in 1592 where he taught mechanics, astronomy, and geometry until 1610. He discovered many things, including kinematics of astronomy and motion and the beginnings of the telescope.[7]

The Assayer

Galileo Galilei’s explicit condemnation of so many Jesuits won him many enemies and may have contributed to his later arrest.

Galileo had a well-known argument over comets with Father Orazio Grassi, a mathematics professor from Jesuit College Romano, in 1916.[8] The original argument involved Galileo criticizing Father Grassi’s “An Astronomical Disputation on the Three Comets of the Year 1618” through an article published under the name of his lawyer called “Discourse on the Comets.”[9]

The article did not cite any solid scientific evidence but mostly insulted Christopher Scheiner, a Jesuit, and disparaged the professors at Collegio Romano.[10] Father Grassi wrote a retort called “The Astronomical and Philosophical Balance.” The Assayer was written in direct response to this in October 1623 and received immediate acclaim as a polemic literary masterpiece.[11]

Heliocentrism Controversy

The Christian world in Galileo’s time believed the sun and the universe revolved around the Earth, geocentrism. Biblical passages created opposition to heliocentrism, but Galileo defended it in his 1610, Starry Messenger.[12] Father Niccolo Lorini turned in Galileo’s heliocentrism writings to the Roman Inquisition in 1615.

On February 26, 1616, Pope Paul V ordered Galileo to withdraw his opinion and banned any works containing heliocentrism and he avoided controversy for a decade. In 1623, Cardinal Maffeo Barberini encouraged him to finish his book, Dialogue Concerning the Two Chief World Systems. He published it in 1632 after obtaining permission from the Pope and the Inquisition.[13]

The Pope requested that Galilei bring two sides to the heliocentrism argument without advocating for it, but the character he used to defend the geocentric view often came across as error-prone and foolish.[14] The Pope did not think this a mistake and he was called by the Inquisition to defend his work in September of 1632.[15]

Arrest and Death

In February 1633, Galileo Galilei faced inquisitor Vincenzo Maculani. He denied his Copernican views and their presence in his Dialogue, even in July 1633 when they threatened to torture him. He was convicted of heresy, sentenced to house arrest, and the court banned Dialogue and any further or future publications of his writing.[16] He first stayed with the Archbishop of Siena, Ascanio Piccolomini, and then returned to his home in Arcetri in 1634.

Galileo remained under house arrest for the rest of his life.

Despite his denials, Galileo Galilei never stopped believing heliocentrism to be correct.

He wrote Two New Sciences while confined and published it in Holland, where it received much admiration from Albert Einstein.[17]

By January 1638, Galileo was completely blind and he petitioned the Inquisition for freedom. They allowed him to move to his Florence house to be attended by physicians. [18] Galileo died on January 8, 1642, and was buried in the Basilica of Santa Croce.[19]

Children of Galilei

Galileo Galilei formed a romantic partnership with Marina Gamba and the couple produced three children out of wedlock, despite Galilei being a devout Roman Catholic. Virginia was born in 1600, Livia in 1601, and Vincenzo in 1606.[20]

All the children were illegitimate, but Galilei believed the dowries for his daughters would be too great for them to marry. He encouraged them to enter Arcetri’s Convent of San Matteo where they remained until their deaths.[21] Vincenzo received legal legitimacy to become Galileo’s official heir and married Sestina Bocchineri.[22]



Drake, S. (1979). Galileo at Work: His Scientific Biography. United Kingdom: University of Chicago Press.

Drake, S. (1990). Galileo: Pioneer Scientist. Canada: University of Toronto Press.

Sharratt, M. (1996). Galileo: Decisive Innovator. United Kingdom: Cambridge University Press.

Van Helden, A. (1995). Galileo Timeline. The Galileo Project.


  1. Van Helden, 1995
  2. Gribbin, J. R. (2007). The Fellowship: Gilbert, Bacon, Harvey, Wren, Newton and the Story of the Scientific Revolution. United States: Overlook Press, Woodstock & New York.
  3. Van Helden, 1995
  4. Reston, J. (2000). Galileo: A Life. United States: Beard Books.
  5. Asimov, I. (1982). Asimov’s Biographical Encyclopedia of Science & Technology (2nd ed.). Doubleday.
  6. Edgerton, S. Y. (2010). he Mirror, the Window, and the Telescope. Renaissance Quarterly, 63(1), 245–246. doi:10.1086/652577
  7. Sharratt, 1996
  8. Sharratt, 1996
  9. Drake, 1979
  10. Sharratt, 1996
  11. Drake, 1979
  12. Blackwell, R. J. (1991). Galileo, Bellarmine, and the Bible. United States: University of Notre Dame Press.
  13. Van Helden, 1995
  14. Galilei, G., & Finocchiaro, M. A. (1997). Galileo on the World Systems: A New Abridged Translation and Guide. United States: University of California Press.
  15. Van Helden, 1995
  16. Sharratt, 1996
  17. Hawking, S. (2003). On The Shoulders of Giants: The Great Works of Physics and Astronomy. United States: Running Press Book Publishers.
  18. Carney, J. E. (2000). Renaissance and Reformation: 1500-1620: A Biographical Dictionary. United States: Greenwood Press.
  19. Find A Grave. (2001, January 1). Galileo Galilei (1564 - 1642). Find A Grave Memorial.
  20. Rosen, J., & Gothard, L. Q. (2009). Encyclopedia of Physical Science. United States: Facts On File.
  21. Sobel, D. (2000). Galileo’s Daughter. London: Fourth Estate.
  22. Coyne, Heller, M., & Zycinksi, J. (1985). The Galileo Affair: A Meeting of Faith and Science, Proceedings of the Cracow Conference, May 24-27, 1984. Vatican City: Specola Vaticana.

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