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Galileo Galilei (15 Feb 1564- 8 Jan 1642)

Name: Galileo Galilei

Birth place: Pisa, Italy

Parents: Vincenzo Galilei (father), Giulia Ammannati (mother)

Occupation: Astronomer, Scientist



Galileo was a mathematics professor who made first observations of nature with long-lasting implications for the study of physics. He also constructed a telescope and supported the Copernican theory, which supports a sun-centered solar system.


Galileo started his formal education at the Camaldolese monastery in Vallombrosa when his family moved to Florence in 1574. In 1583, he entered the University of Pisa. With his outstanding intelligence and talent, he became fascinated with many subjects, particularly mathematics and and physics. However, due to financial difficulities, he had to drop out of university in 1585 before he earned his degree.


Galileo continued studying mathematics and supported himself with minor teaching positions. During this time he began his two-decade study on objects in motion and published The Little Balance, describing the hydrostatic principles of weighing small quantities, which brought him some fame. This gained him a teaching post at the University of Pisa, in 1589.


In 1604, Galileo published The Operations of the Geometrical and Military Compass, revealing his skills with experiments and practical technological applications. He also constructed a hydrostatic balance for measuring small objects. These developments brought him additional income and more recognition. That same year, Galileo refined his theories on motion and falling objects and developed the universal law of acceleration, which all objects in the universe obeyed. Galileo began to express openly his support of the Copernican theory that the earth and planets revolved around the sun.


In July 1609, Galileo developed a simple telescope of his own. In August, he demonstrated it to some Venetian merchants, who saw its value for spotting ships and gave Galileo salary to manufacture several of them. Galileo’s ambition pushed him to go further. In the fall of 1609, he made the fateful decision to turn his telescope toward the heavens. In March 1610, he published a small booklet, The Starry Messenger, revealing his discoveries that the moon was not flat and smooth but a sphere with mountains and craters. He found Venus had phases like the moon, proving it rotated around the sun. He also discovered Jupiter had revolving moons, which did not revolve around the earth.


Galileo was eventually threatened with torture by the church as his findings strongly opposed the Catholic's beliefs. He was convicted of heresy and spent his remaining years under house arrest. While under house arrest, Galileo wrote Two New Sciences, a summary of his life’s work on the science of motion and strength of materials. It was printed in Holland in 1638. By this time, he had become blind and in ill health.


In time, the Church could not deny the truth in science. In 1758, it lifted the ban on most works supporting Copernican theory, and by 1835 dropped its opposition to heliocentrism altogether.


Adapted from

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