HomeScientistGalileo Galilei: The Astronomer Who Changed the World

Galileo Galilei: The Astronomer Who Changed the World

The greatest Renaissance thinker, Galileo Galilei founded modern mechanics, physics, and astronomy. He also followed Copernicus’ theories and was Newton’s forerunner.

On February 15, 1564, in the Italian city of Pisa, the future scientist was born. The father of Vincenzo Galilei was a poor aristocrat who published treatises on music theory and played the lute. Vincenzo belonged to the Florentine Camerata, an organization whose goal was to bring back classical Greek tragedy. At the turn of the 16th and 17th century, a new genre of opera was created as a consequence of the efforts of singers, poets, and musicians.

In addition to managing the household, Mother Giulia Ammannati reared four children: Michelangelo, Virginia, Livia, and Galileo, the oldest. The youngest son continued his father’s legacy and went on to become well-known for his compositions. The family relocated to Florence, the Tuscan capital, when Galileo was eight years old. Here, the Medici dynasty flourished and was well-known for its support of scientists, painters, singers, and poets.

Galileo was transferred to the Benedictine monastery of Vallombrosa for his early education. The youngster shown aptitude in the exact sciences, languages, and painting. Galileo’s father gave him a gift for writing and an ear for music, but the young man was genuinely drawn to science alone.


Galileo arrived in Pisa to attend the university and study medicine at the age of 17. The young man developed an interest in mathematics lessons in addition to the core subjects and medical practice. Galileo’s perspective was impacted by the young man’s discovery of the universe of geometry and algebraic formulas. The young guy spent three years studying at the university, reading widely from the writings of Greek scientists and thinkers and learning about Copernicus’ heliocentric thesis.

Galileo was forced to return to Florence after three years of study at the educational institution because his parents could not afford to pay for him to continue his education. The gifted young man was not given the chance to finish the course and earn a degree by the university administration, nor were they willing to make any accommodations for him. However, Marquis Guidobaldo del Monte, a prominent benefactor who recognized Galileo’s aptitude for invention, was already a fan. Before the Tuscan Duke Ferdinand I de’ Medici, the aristocrat defended his protégé and gave him a job at the monarch’s court.

Employed by the University

The gifted scientist was given assistance by the Marquis del Monte in obtaining a teaching post at the University of Bologna. Galileo was not just a lecturer but also a productive scientist. The scientist pursued studies in mathematics and mechanics. The philosopher taught mathematics at the University of Pisa for three years when he returned there in 1689. He relocated to Padua, in the Venetian Republic, in 1692 and stayed there for eighteen years.

By combining his profession as a professor at the nearby university with scientific research, Galileo authored two books: “On Motion” and “Mechanics,” in which he challenged Aristotle’s theories. During these years, a significant development occurred: a telescope was created by a scientist, enabling the observation of life on celestial bodies. The astronomer wrote a book titled “The Starry Messenger” detailing the findings made by Galileo using the new instrument.

Once again in Florence in 1610, Galileo published his “Letters on Sunspots” while being looked after by Tuscan Duke Cosimo Medici II. The Catholic Church did not approve of this publication. The Inquisition was a widespread institution at the start of the 17th century. Furthermore, zealots of the Christian faith gave special consideration to Copernican adherents.

Giordano Bruno, who never abandoned his opinions, was burned at the stake in 1600. Galileo Galilei’s writings were therefore viewed as offensive by Catholics. The scientist thought of himself as a model Catholic and could not perceive any conflict between his research and the worldview that is centered on Christ. The Bible, according to the astronomer and mathematician, is a book that aids in soul salvation rather than a work of science.

Galileo traveled to Rome in 1611 to show Pope Paul V the telescope. The scientist even got the go-ahead from the astronomers in the capital after presenting the apparatus as accurately as possible. However, in the view of the Catholic Church, the scientist’s destiny was sealed when he asked to make a definitive conclusion regarding the world’s heliocentric system. Galileo was charged with heresy by the Papists, and the trial began in 1615. In 1616, the Roman Commission formally declared heliocentrism to be erroneous.


Recognizing the objectivity of the world despite human subjective perception is the central tenet of Galileo’s worldview. The universe was created by a divine impulse and is infinite and eternal. Nothing in space vanishes completely; instead, matter undergoes a transformation. The mechanical motion of particles, which can be studied to comprehend the laws of the universe, is the foundation of the material world. As a result, the foundation of scientific inquiry should be experience and sensory understanding of the outside world. Galileo believed that the true subject of philosophy is nature, through which one might approach the truth and the source of all things.

Galileo supported both the experimental and logical approaches to natural science. While the second strategy presumed a steady flow from experiment to experiment to attain whole knowledge, the first method let the scientist prove theories. The philosopher mostly used Archimedes’ teachings in his writing. Galileo, while criticizing Aristotle’s ideas, did not disagree with the ancient philosopher’s analytical approach.


Galileo was able to observe celestial bodies because of the telescope he built in 1609, which was made with a convex objective and a concave eyepiece. However, the original device’s three-fold magnification was insufficient for the scientist to carry out comprehensive studies, so soon after, the astronomer invented a telescope that could magnify objects by a whopping 32 times.

The Moon was the first celestial body that Galileo thoroughly examined using the new instrument. On the satellite’s surface, the scientist found a large number of mountains and craters. The initial finding established that the physical characteristics of Earth are the same as those of other celestial bodies. This was the initial challenge to Aristotle’s claim on the distinction between celestial and earthly nature.

The discovery of four satellites of Jupiter, which was verified by multiple space photos in the 20th century, was the second significant discovery in astronomy. Thus, he disproved the opponents of Copernicus’ theory that the Earth cannot revolve around the Sun if the Moon circles around the Earth. Galileo was unable to determine the period of rotation of these satellites because of the limitations of the early telescopes. Astronomer Cassini presented the last evidence of Jupiter’s moons rotating seventy years later.

After a protracted period of observation, Galileo made the discovery that sunspots exist. Galileo came to the conclusion that the Sun revolves around its own axis after studying the luminary. The astronomer discovered that Venus and Mercury have orbits that are closer to the Sun than Earth’s. Due to technological limitations, Galileo was only able to describe the planet Neptune and identify the rings of Saturn, but he was unable to make any more progress in these discoveries. After using a telescope to view the Milky Way’s stars, the scientist became convinced of their enormous quantity.

The Earth rotates around its own axis in addition to around the Sun, as demonstrated by Galileo’s empirical and experimental evidence, which confirms Copernicus’ theory as accurate. After receiving a warm welcome at the Vatican, Galileo joins the Prince Cesi-founded Accademia dei Lincei in Rome.

The Mechanics

Galileo believed that mechanical movement was the foundation of all physical processes in nature. The scientist believed that everything in the cosmos is a sophisticated system made up of the most basic causes. Consequently, mechanics emerged as the central theme of Galileo’s scientific research. In addition to making numerous discoveries in the area of mechanics, Galileo also established the course for later advances in physics.

The rule of fall was first established and empirically confirmed by the scientist. Galileo found the mathematical expression that describes how a body traveling at an angle to a horizontal surface might fly. When calculating artillery tables, it was crucial to consider the parabolic velocity of the projectile.

Galileo created the law of inertia, which is now considered to be the foundational principle of mechanics. The validation of the relativity principle for classical mechanics and the computation of the oscillation formula for pendulums were two further discoveries. According to the latter study, the physicist Huygens created the first pendulum clock in 1657.

Galileo was the first to point out a material’s resistance, which sparked the emergence of independent science. The scientist’s theories later served as the foundation for the principles of physics governing the moment of force, which is the conservation of energy in a gravitational field.


Galileo’s mathematical rulings touched on the concept of probability theory. Published 76 years after the author’s passing, the treatise “Discourses on the Game of Dice” contained the scientist’s personal research on this topic. The well-known mathematical conundrum involving natural numbers and their squares was created by Galileo. Galileo’s “Conversations on Two New Sciences” has a recording of his calculations. The theory of sets and their classification derived from this study.

Disagreement with the Church

Following the pivotal year of 1616 in Galileo’s scientific career, he was compelled to remain hidden. Galileo only published “The Assayer” in 1623, the sole book he wrote after Copernicus was labeled a heretic, because the scientist was too scared to publicly voice his own opinions. Galileo felt rejuvenated following the Vatican’s power shift and thought that the new Pope Urban VIII would be more accepting of Copernican concepts than his predecessor.

However, the Inquisition tried the scientist once again following the publishing of the controversial work “Dialogue Concerning the Two Chief World Systems” in 1632. The charge story was repeated, but Galileo’s outcome was far worse this time.

Individual life

Young Galileo met Marina Gamba, a Venetian Republic citizen, while he was living in Padua. Gamba eventually became the scientist’s common-law wife. Galileo’s family had three children: Virginia and Livia, two daughters, and Vincenzo, a son. The girls were later forced to become nuns because the children were born out of wedlock. Galileo, who was 55 at the time, was only able to legalize his son, allowing him to be married and have a grandchild who would grow up to be a monk like his aunts.

Galileo Galilei

Following Galileo’s excommunication by the Inquisition, he relocated to a property in Arcetri close to the daughters’ convent. Consequently, Galileo had frequent opportunities to see his beloved, Virginia, the eldest daughter, until her death in 1634. Because of her condition, the younger Livia did not see her father.


Following a brief period of incarceration in 1633, Galileo rejected the notion of heliocentrism and was placed under house arrest indefinitely. In the city of Arcetri, the scientist was put under house arrest with no means of communication.
Until his latter days, Galileo never left the Tuscan mansion where he lived. On January 8, 1642, the genius’s heart stopped. Viviani and Torricelli were the two students with the scientist at the time of his death. “Dialogues” and “Conversations and Mathematical Proofs Concerning Two New Branches of Science,” the thinker’s final two publications, were published in Protestant Holland in the 1930s.

Galileo desired to be buried in the vault of the Santa Croce Basilica, but Catholics prohibited this after his death. There was justice in 1737. Galileo’s tomb is now situated adjacent to Michelangelo’s. Twenty more years on, the church revived the notion of heliocentrism. The validation of Galileo took a much longer to arrive. Pope John Paul II acknowledged the error of the Inquisition only in 1992.



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