Galileo was born in Pisa, on February 15, 1564. His family belonged to the Florentine nobility.
In 1574, he and his family moved to Florence, where Galileo received a fine artistic and literary education. His family was dealing with serious economic problems, thus his father hoped Galileo would study medicine. In 1581, he began studying at the University of Pisa.
While at the University of Pisa he formulated the isochronisms law of the pendulum, after observing a suspended lamp swinging back and forth in the cathedral of Pisa. In 1585, Galileo left Pisa in order to make his return to Florence without having achieved any academic degree.
Here he wrote the "Theoremata circa centrum gravitatis solidorum" and developed the invention of the hydrostatic balance.
In 1589, Galileo was appointed professor of mathematics at the University of Pisa.
Meanwhile, after his father's death, he had to take charge of his family. While facing a very precarious financial situation, he managed to be appointed professor of mathematics at the University of Padua in order to improve his financial and working conditions. The 18 years spent there are considered the happiest and most peaceful years of his entire life.
Regarding his private life, during this time, he had a relationship with a Venetian woman Marina Gamba, who lived in Galileo's house in Padua and who bore him three children: two daughters and one son.
In 1609, he rediscovered and improved the telescope. With it, he was able to observe the celestial phenomena, he made new and important discoveries, such as the mountainous terrain of the moon, the recognition of unknown stars and the discovery of the four satellites of Jupiter called Astri Medicei.
These discoveries were presented to the international scientific community in Sidereus Nuncius. Shortly afterwards he was appointed the most illustrious mathematician and philosopher of the Grand Ducky, without having the duty of teaching and very favourable financial conditions.
During the same year, he discovered the phases of Venus, sunspots and the rings of Saturn.
In 1611, he made his return to Florence. After having had a general consensus among the major astronomers and mathematicians of his time, he decided to go to Rome to show his discoveries. But he found himself bitterly opposed by the traditionalist scientists and only the Jesuits of the Roman Collegio approved his discoveries and theories.
However, the Inquisition already suspected him of heresy.
He strongly argued with a Jesuit and, writing the four famous "Copernican Letters" he had to recognize the limits between science and faith.
Despite the support of his influential friends, on February 24, 1616, he was warned by Cardinal Bellarmino, that he could no longer discuss or teach Copernican theories because they were not compatible with the Roman Catholic faith; otherwise he would have been imprisoned.
Although he felt deeply disappointed, his strong convictions led him to debate his beliefs again. With his main controversial work, "Il saggiatore", he achieved great success.
In 1624, he started writing the book "Dialogue Concerning the Two Chief World Systems". But his revolutionary work immediately caused the reaction of the Inquisition. The book was impounded and Galileo was called to Rome to face the Inquisition again. He was processed for heresy and condemned for disobeying the orders of the Church.
The process ended in 1633. Thanks to his international fame and his submission act, he was condemned to a formal prison. At first he was banished in Siena and later was sent to his home in Arcetri, outside Florence. On January 8th, 1642, Galileo died at his home.
Only in 1763 his remains were put in the Basilica di Santa Croce in Florence.