Brilliant Beginnings
The son of a famous musician and music theorist, Galileo was born near Pisa, Italy. He was educated by monks at Vallombrosa, then entered the university of Pisa in 1581 to study medicine. There, he found his interests changing to philosophy and mathematics and he ended his university career in 1585 without a degree.Despite his lack of a degree, he tutored privately for a while until he became professor of mathematics at Pisa in 1589. Legend has it that while teaching there, he demonstrated to his students that Aristotle was wrong about speed of fall being related to the weight of an object by dropping two items off the leaning tower.
Contradicting Aristotle was considered almost a heresy by many at the time, and he was not invited back to the university in 1592. That same year, though, he secured a position as chair of mathematics at the University of Padua. He remained there until 1610.
Joining the Establishment
Galileo thrived at Padua where he invented an early calculator called a compass which helped solve complex mathematical problems. He began studying physics, discovering the law of falling bodies as well as the parabolic path of projectiles. He also studied the motion of pendulums, began studying mechanics and material tactile strengths. He professed no interest in Astronomy, though he did favor the Copernican universe model over the Ptolemaic or Arisotalian.After learning of the invention of the spyglass in Holland, he built a telescope of his own, which had a magnification factor of 20. With this new tool, he found mountains and craters on the moon, discovered that the Milky Way was composed of stars, and discovered the four largest moons of Jupiter. After publishing his findings in The Starry Messenger in March of 1610, he was appointed court mathematician at Florence, freeing him from his teaching duties and giving more time for research. By December, he had observed the phases of Venus, further contradicting Ptolemy and confirming the Copernican theory.
Heresy
Many scientists of the day disputed Galileo's discoveries and theories, often because of their disagreement with Aristotle. In 1614, a priest in Florence denounced him and his followers from a pulpit, causing Galileo to compose an open letter on the irrelevance of the bible in scientific arguments and that scientific positions should never be made articles of Roman Catholic faith.In 1616, Copernican books were censored by the church and Galileo was told by cardinal Robert Bellarmine to no longer defend the concept that the Earth moves. He made no complaints, continuing his work on determining longitudes at sea, based on his predictions of the positions of Jupiter's satellites. He continued to study falling objects and penned a book on Comets called The Assayer, which was published in 1623.
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