Galileo Galilei was born in Pisa, Italy on February 15, 1564. His father was Vincenzo Galilei, who was a famous composer and lutenist. His father was also a “patrician (a member of the local aristocracy), but the family was not very wealthy” (Ryan). As Galileo grew up, he chose to go down the path of being a medical student due to his father’s wishes and began his formal education at Florence’s Vallombrosa monastery. Then, in 1581, he entered the University of Pisa as a medical student but realized that medicine was not his interest, and he’d much rather work in the fields of mathematics, physics, and philosophy. In 1585, Galileo dropped out of the University of Pisa without a degree and started focusing on the fields of science that actually interested him. After dropping out of University, Galileo became a math and physics tutor while simultaneously working on a hydrostatic balance which he succeeded with and wrote a manuscript about, called La Balancitta (The Little Balance), which came out in 1586. After the release of the book Galileo continued working as a math and physics tutor until 1589, during that year he was selected as the chair of mathematics and a professor at the University of Pisa. For the next 2 years he continued teaching and managing the mathematics department of the university until 1591. During this year Galileo’s father died, and he was entrusted to take care of his younger brother Michelangelo.”In 1592, Galileo went to the University of Padua, west of Venice, to teach mathematics” (Ryan). He taught different types of subjects that used mathematics such as geometry, mechanics, and astronomy. During his 18 years at Padua he made lots of discoveries and inventions such as testing out the strength of different materials, inventing the water pump, designing a more efficient method for the placement of oars in ships’ galleys, making important observations about the motion of the pendulum, creating one of the first thermometers (which depended on temperature and pressure), and one of his most important inventions, the telescope. But, these 10 years weren’t just discoveries and teaching, but also financial problems. Galileo’s two sisters got married during these 10 years, and he was the one who had to pay their dowries. He couldn’t afford these dowries, so he borrowed some money to pay one sister’s husband, which put him into debt, while he arranged a down payment to the other sister’s husband and agreed to pay a certain amount every year until it was paid off. During the first year that payment was about half of his total annual salary. He had to make some extra money somehow, so he leased a house and tutored students for some extra pay: To supplement his income Galileo leased a large house. There he boarded students and taught them privately. These young aristocrats had interests beyond academic studies. Soon they would return home to take charge of their estates. Galileo taught them practical mathematical subjects such as surveying and how to fortify their castles. (MacLachlan 29-30)He was able to enhance his income to nearly 1,000 florins per year.In 1604 “Galileo turned his attention toward astronomy when the appearance of a supernova triggered speculation among scholars and casual observers . . . Galileo took the event as a sign that the structure of the universe was not immutable, and began looking for a way to prove the validity of Copernicus’ heliocentric theory” (Ryan). This theory said that the Sun, and not the Earth was in the middle of our system and that Earth was just like the other planets and revolved around the Sun. The belief in this theory was rare and actually punishable by law which was seen in 1600 when Giordano Bruno, a mathematician and cosmological theorist, was burned at a stake for believing in it. Although Galileo didn’t come out and publicly support this theory he was a very strong believer of it and spent years trying to prove it in a way that would get the public on his side. One such way was the invention of the telescope, which Galileo wasn’t the sole creator of and actually used a Dutch spectacle-maker’s findings to create it in 1609. Using this telescope (which he didn’t have a name for until 1611) Galileo was able to discover tons of new things about space including the fact that the moon was not smooth but filled with mountains and craters all over, a plethora of previously undiscovered stars, and found Jupiter’s four largest satellites. When he first saw the moon through one of the first iterations of his telescope he saw the moon a bit clearer but still very blurry but was still very excited and went to show off his new instrument to the Venetian senate which enjoyed using the instrument for hours on end on top of a church. When Galileo improved his design of the telescope he decided to gift one to the Venetian senate and “in return for his kindness the senate gave him a lifetime contract at the University of Padua. They also increased his salary to 1,000 florins” (MacLachlan 48). Galileo took the job and continued trying to improve his telescope.After a couple of months of grinding lenses Galileo perfected his telescope and pointed it again at the moon. This time he saw craters and moons covering and surface of Earth’s satellite and started sketching the features of the Moon throughout all of its phases. After he was done with the moon he pointed the telescope to Jupiter and noticed something weird, a group of 3 starlets were near the equator of the planet, he expected that when he would check again the next night that the starlets would be gone because they were in the background but what he saw was that those starlets followed Jupiter around. Galileo realized that those weren’t starlets but the moons of Jupiter. “Here, for the first time, Galileo had new evidence that might support the Copernican system. Jupiter is a planet, and Jupiter has moons. Since the earth has a moon, maybe the earth is a planet circling the sun” (MacLachlan 50). Now, Galileo finally had some evidence that the Ptolemaic system (which said that the Earth is the center of the Solar System and that everything revolved around it and no other object was the center of any rotations) was at least partially invalid. With these findings, Galileo wrote a book and called it Sidereus nuncius (Starry Messenger) and released it in 1610. He wrote the book in Latin so other scholars across Europe could read it, and sent them out. After sending the book out, Galileo wanted to return to his homeland (Florence) and so he went about doing so by meeting with the Duke, Cosimo de’ Medici. The Duke agreed to let him come and “he was appointed chief mathematician, without teaching duties, at the University of Pisa. In addition, he was named Philosopher and First Mathematician to the Grand Duke of Tuscany” (MacLachlan 52). He was also absolved from paying any more dowries for his two sisters and his salary was made the same as the one in Padua.The next couple of years Galileo who now had a strong position of influence became more confident in his belief of the Copernican theory and also became more public with it. So much so that he started disproving people that believed anything else, publicly. This rubbed a group of philosophers (called the Pigeon League by Galileo and his friends) the wrong way because they could not refute Galileo’s claims, so they turned their focus to something else, religion. They contacted a priest Tommaso Caccini who read the work of Galileo and found it heretical, he contacted the Inquisition in Rome and after consulting with theologians they found Galileo’s work to not be heretical. Galileo, hearing word of this thought that he need to help the Church not make an error: He needed to protect himself if the authorities were going to charge him with heresy. Even if they were not, he decided to protect the Church from serious error, in case it wanted to condemn the Copernican system. He felt that the Church could become a laughingstock if it ruled against the earth’s motions, which might later be proved to be real. (MacLachlan 81)When Galileo got to Rome though, the important officials were much nicer to him than before and his mind was set at ease. Until a couple of months later, Galileo hypothesized that the tides move because the Earth moves. He wrote a letter saying this to a friendly young cardinal by the name of Alessandro Orsini who brought it to the attention of Pope Paul V. The Pope was outraged and ordered Galileo to abandon the speaking about and writing about of the Copernican system. Galileo agreed to it and went back to Florence to continue studying motion. In 1623, a new Pope was chosen. This new Pope, Urban VIII, was a friend of Galileo and his friends and so Galileo dedicated his new book The Assayer to the new Pope. The Pope was pleased with the elegant writing and in 1624 Galileo traveled to Rome to pay homage to his friend-turned-pope. Meeting with the Pope, Galileo asked if the ban on Copernicus could be lifted but the Pope said no. He did give Galileo permission to write about the Copernican theory only if he compared it to Ptolemy’s theory. Galileo returned to Florence and started writing a book called Dialogue which had three characters all representing something. One represented the Copernican theory, the other Ptolemy’s theory (which was portrayed as a simpleton), and another represented a common sense individual. In the book, the simpleton had a line that the Pope asked Galileo to put in. Pope Urban took the fact that the simpleton said his line as an offense and quickly turned against Galileo, ordering the Inquisition to investigate Galileo and his new book. The Inquisition agreed that the book was heresy and called upon Galileo to come to Rome in 1633 so they could interrogate him. He came to Rome and was held in the Vatican for months while at the same time being interrogated. In the end, “the Inquisitors found Galileo guilty of vehement suspicion of heresy” (McMullen) due to his support of the Copernican system and because he disobeyed his orders from 1616 to never again talk or write about the system. He was then allowed to relocate to the village of Arcetri, which was a couple of miles outside of Florence.In Arcetri, he spent his final years writing his most influential book called Dialogues Concerning Two New Sciences. This book instead of focusing on astronomy focused on “combining the principles of mathematics, geometry and physics, and defining the laws of falling bodies, acceleration, and projectile motion” (Ryan). It took Galileo years to write it and because there was a ban on him publishing books in Italy looked for people outside of the country to publish it. He found a patron in Germany who agreed to publish his book but that scholar suddenly died. He deserted the project for some time until he found another patron from Holland who agreed to publish the book. The book was published in 1638 and by that time Galileo was blind in both eyes and couldn’t see. A young man by the name of Vincenzio Viviani became Galileo’s secretary during this time until his death and helped Galileo write letters to both friends and foes. In late 1641, Galileo was bedridden with kidney pains and on January 8th, 1642, Galileo passed away in his sleep. He was buried in the rear chapel of a church in Florence, and only in 1737 were his remains moved to the main part of the church with the Inquisition’s permission.