Galileo Galilei, often known as Galileo, was an Italian physicist, mathematician, engineer, astronomer and philosopher. He lived in Italy from 15 February 1564 to 8 January 1642. Galileo played a major role in the scientific revolution during the Renaissance. Thus, Galileo has been called the “father of modern observational astronomy“, “father of modern physics“, “father of science” and “the father of modern science“.
Galileo was born in Pisa, Tuscany. His family moved to Florence in the early 1570s, where they lived for generations. In 1581, Galileo matriculated at the University of Pisa, where he studied medicine as physicians earned much more than mathematicians. However, he became enamoured with mathematics and made it his profession. He then became the Mathematics Chair for Padua until 1610. At this point, he moved to Florence, to join the court of the Medicis.
Hans Lippershey, in the Netherlands, made the first practical telescope in 1608. After hearing the descriptions, Galileo made a telescope with about three times the magnification in the following year. He taught himself the art of lens grinding and quickly figured out how to improve the instrument. He, thus, produced increasingly powerful telescopes, reaching one with upto 30 times magnification.
In December 1609, he drew the moon’s phases as seen through the telescope. These show that the moon’s surface is not smooth, but is rough and uneven – contrary to popular belief at the time. He discovered four moons revolving around Jupiter in January 1610. This was shocking to most since the Aristotelian theory postulated that everything revolved around Earth. Galileo quickly produced a little book called Sidereus Nuncius (The Sidereal Messenger), in which he described these discoveries. He named the moons of Jupiter after Cosimo II de Medici, but they were soon after renamed in his honour.
Galileo was prosecuted for stating that the Earth revolves around the Sun. At the end of his trial, he formally recanted his conclusions. Yet, there is an unverifiable rumor that under his breath he whispered “Eppur si muove” meaning, “And yet it moves” – reaffirming that Earth indeed underwent rotational and revolutionary motions.