Galileo was an Italian mathematician, astronomer, and physicist. He was born in Pisa, Italy on February 15, 1564. In the mid 1570ís, he and his family moved to Florence and he started his formal education in a local monastery. He was sent to the University of Pisa in 1581. While there, he studied medicine and the philosophy of Aristotle until 1585. During these years at the university, he realized that he never really had any interest in medicine but that he had a talent for math. It was in 1585 that he convinced his father to let him leave the university and come home to Florence. Back in Florence, he spent his time as a tutor and began to doubt the Aristotleís philosophy.
In 1589, he was made professor of mathematics at the University of Pisa where he attended school. His position also required him to teach astronomy based on Ptolemyís theory that all planets and the sun revolved around the earth. In 1592, he left the University of Pisa and went to the University of Padua to become professor of mathematics. During his time there, he constructed a clumsy thermometer which would have work if he had taken into consideration atmospheric pressure but it still has a significance in history as being one of the first measuring instruments in science. He taught he for 18 years and during that time, became convinced that there was truth in the theory of Nicolaus Copernicus a Polish astronomer who believed that all planets including earth revolved around the sun.
While still at Padua, in 1609, he built the first astronomical telescope. When he used it to look at the sky, he easily found that most of Aristotleís and Ptolemyís theories were wrong. His most important discovery was when he discovered the four moons of Jupiter in 1610. Later that year Cosimo de Medici, Grand Duke of Tuscany, named Galileo his personal mathematician. This brought him back to Florence once again here he continued his studies in astronomy. Galileo also studied motion, especially that of freely falling objects. While watching swinging lamps in church one day, he noticed that it takes the same time between swings no matter how big or small the arc is. This observation led to his invention of the pendulum clock. He also discovered, before Newton, that two objects of different weights fell at the same speed. For instance, if you dropped an orange and an eggplant from the same height at the same time, they would hit the ground at the same time.
In 1613, he wrote a letter where he tried to explain how the Copernican theory was agreed with both Catholic doctrine and correct Biblical explanation. A few of his enemies got letter, and sent it to the inquisitors in Rome. What the inquisitors did, was find and discipline people who were against the teachings of the church. Galileo was brought to Rome to be tried. Fortunately for him, his charges were cleared and he was let go under one condition that was that he was not to hold or defend the Copernican theory. What this meant was that he wasnít allowed to say it was true. Nineteen years later, in 1632, he published his first book, Dialogue Concerning the Two Chief World Systems. In this composition, he compared Aristotleís and Ptolemyís theories to that of Copernicus. He did this to show that the Copernican theory was more logical than the other two. Again the inquisitors tried him and this time he was found guilty. He was given to life imprison but due to his old age and poor health, he was allowed house arrest in his home just outside of Florence. He eventually went completely blind and still managed to write his second book. He died on January 8, 1642, at the age of 78. His discoveries about the timing of a pendulum swing, and that of how two objects of different weights fall at the same speed have benefited our society in more ways than are listable.