The Life and Career of Galileo Galilei

Galileo’s Career

Galileo Galilei the Teacher: Galileo was a very religious young man and was drawn to becoming a priest, but his father wanted him to study medicine. However, he naturally became drawn to the study of mathematics. He convinced his father to let him change subjects. One story about how he first became interested in mathematical concepts tells of how he watched a swinging chandelier and noticed that no matter how far out the chandelier swung, it always took the same amount of time to cover the distance. He decided to experiment. While studying mathematics, he became passionate about Art and worked as an art teacher for a time.

Galileo settled into a teaching career in 1589, first in Pisa and later at the University of Padua. Part of his reason for doing this was to support his younger brother after his father died. He taught mathematics, astronomy, and mechanics. Still, all the while, he was working on his own experiments, formulating theories about what he observed and testing them using what we would now recognize as the scientific process, but what was then quite a new concept.

Astronomy: Galileo Galilei had a keen interest in astronomy, and it was his work in this field that would prove to be some of his most brilliant and groundbreaking discoveries, and also the cause of much controversy and pain in his life. In 1609, he designed a telescope capable of magnifying by three times. This might sound fairly simple to us, but it was an incredible innovation for the time. While the telescope was not necessarily invented by Galileo (a patent was submitted in 1608 by Hans Lippershey), he refined the idea and was the first to use the telescope for astronomy. In 1610, he made an incredible discovery; the four moons of Jupiter. These are still known as the Galilean moons (Io, Callisto, Europa, and Ganymede). He also discovered the rings of Saturn and identified craters and hills on the moon. While making his observations of the phases of Venus, it occurred to him that it didn’t make sense that everything revolved around the earth, which was the accepted belief of the time. He suggested that it was, in fact, the sun that was at the center of the solar system and that everything else revolved around it. This idea is known as heliocentricity and was also proposed by Copernicus. Galileo used his scientific method to experiment with his ideas, testing his hypothesis in ways that had not been attempted before.

In 1632, Galileo was allowed to publish a new work containing the heliocentric theory called Dialogue Concerning Two Chief World Systems. The new Pope asked Galileo to give both sides of the argument; the geocentric (earth is at the center of the solar system) and the heliocentric (the sun at the center).  However, when the book was published, the Pope was angry and insulted by it. He felt that Galileo was ridiculing the geocentric model. Galileo had to travel to Rome to defend himself at a trial. He argued that he had obeyed the law and abandoned the active promotion of his ideas. Essentially, Galileo’s theory simply made more sense than the old, accepted alternative, and so his book naturally looked as though it was defending it. He was convicted of heresy and imprisoned in 1633 but soon after was allowed to swap prison for house arrest. He is famously believed to have recanted his theory that the earth moves, only to follow this with the words ‘E pur si muove’ (‘And yet it moves’).