Galileo di Vincenzo Bonaiuti de’ Galilei is one of the most famous astronomers in the world. He’s often considered to be the father of modern science since he made major contributions to the fields of physics, mathematics and philosophy. He is the central figure of the Scientific Revolution of the seventeenth century.
As many, the story I learned about Galileo was when how he challenged the Catholic Church and their teachings about the solar system. They believed the Earth was the center of the Solar System and he was crucified for going against the teachings of the church and became a martyr for science. This belief was further cemented when I heard the first lines of a song called “Galileo” by the Indigo Girls:
“Galileo’s head was on the block,
the crime was lookin’ up the truth.”
It wasn’t until many years later that I learned that he wasn’t killed by the church and lived to be 77 years old. However, when he died, he was under house arrest.
Galileo was born February 15, 1564 in Pisa, Italy. His father, Vincenzo, was a court musician and authored some music theories while his mother, Giulia Ammannati, was a descendant of cloth merchants. When it was time him to go a university, he enrolled in the University of Pisa in 1580 to earn a medical degree. He never earned it and actually studied mathematics. From 1589 to 1610, Galileo was chair of mathematics at the universities of Pisa and then Padua. In the latter years, he began investigating hydrostatics and the strength of materials and continued his studies on motion that leads to the discovery of the parabolic path of projectiles.
All his projects came to halt in 1609 when he took a new spyglass and improved the magnification on the lens and pointed it at the sky. He eventually was able to increase the magnification by 30 times. From here, most know the history of his discoveries, such as the large moons Jupiter, often referred to as Galileo’s moons, Io, Europa, Ganymede, Callisto. He also was the first to see the Rings of Saturn! (Although with the strength of his magnification, he couldn’t actually see the rings, which is why he described them “handle” or “ears”.) He was also the first to see that the Moon wasn’t a smooth sphere; that there were hills and craters on the surface. He even saw sunspots and rushed to put his observations in a pamphlet in 1610 called, “Sidereus Nuncius,” which is Latin and translates to “Starry Messenger.” Between being able to show prominent leaders his observations and having mathematicians verify them, such as, Johannes Kepler, who wrote a letter in support of his pamphlet, the pamphlet catapulted Galileo onto the world stage. With its success, Galileo is appointed as the “Chief Mathematician of the University of Pisa and Philosopher and Mathematician to the Grand Duke of Tuscany” for life.
Empowered by his successes, in 1613, Galileo wrote “Letters on Sunspots,” where he expresses support for heliocentrism, the sun being in the center of the solar system. In 1616, Galileo wrote his theory about the tides in which he argues that it is proof that the Earth moves. A month later, on the orders of the Pope Paul V, Cardinal Bellarmine goes to Galileo’s residence to warn him not to defend the Copernican theory. It would about a decade later when Galileo get the attention of the Church.
In 1623, Maffeo Barberini, Galileo’s supporter and friend, was elected Pope Urban VIII. The following year the Pope assured him that he could write about the Copernican theory as long as he treated it as a mathematical hypothesis. As a result, Galileo began to work on a “Dialogue Concerning the Two Chief World Systems.” The “two systems” were the Ptolemaic and Copernican, both of which supported the heliocentrism. It would take Galileo ten years to finish it. He worked with the Inquisition and censors for getting it printed. In 1632, its distribution is prohibited by Pope Urban VIII and a special commission is appointed to examine the book who refers it to the Inquisition. They meet with the Pope and it’s decided to summon Galileo to Rome.
Galileo receives the summons and requests the trial be moved to Florence. His request is denied. The Florentine Inquisitor informs Rome that he had visited Galileo, who was ill, in bed and that three physicians had signed a statement that he was too ill to undertake the journey to Rome. At another meeting again presided over by Pope Urban VIII, himself, the Inquisition rejects Galileo’s request as a ruse and sends him notice that if he does not come to Rome voluntarily, he will be arrested and brought to Rome in chains.
Galileo arrived on February 13, 1633. He is formally interrogated by the Inquisition. He is detained in the building of the Inquisition but in a comfortable apartment. A plea bargain is made where Galileo will plead guilty to lesser charges and will receive a lenient sentence. On April 30, Galileo confesses that he may have made the Copernican case in the “Dialogue” too strong and offers to refute it in his next book. Pope Urban VIII decides that Galileo will be imprisoned for an indefinite period. The sentence is signed by seven of the ten cardinal-inquisitors.
In a formal ceremony at the church of Santa Maria Sopra Minerva, Galileo denies his errors.
He is allowed to be under house arrest at the residence of the Tuscan ambassador and then at the residence of the archbishop of Siena. There he begins putting together his Discourse on Two New Sciences. Eventually he is allowed to return to his villa in Arcetri, near Florence, where he remained under house arrest for the remainder of his life.
It’s now known for the Arcetri Astrophysical Observatory.
