Galileo Galilei: Biography, Facts, & Things You Don't Know Yet

By | February 13, 2021

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Italian astronomer and physicist Galileo Galilei (1564–1642) using a telescope, circa 1620. (Hulton Archive/Getty Images)

Much like Madonna and Cher, Galileo was a thought leader so revolutionary that we know him by only his first name. He made major contributions to the fields of astronomy and mathematics, but he made a powerful enemy of the Catholic Church and even narrowly avoided being burned at the stake for suggesting that perhaps the secrets of the universe expanded beyond what was known in medieval times.

Galileo's Early Years

Galileo Galilei was born in 1564 in Pisa, Italy as the oldest of Vincenzo Galilei's six children. Galileo turned out to be so bright and inquisitive that he enrolled in the University of Pisa when he was only 16 years old, intending to study medicine before discovering a new passion in mathematics. He was especially interested in how math explains the movement of objects, and within just two years, he published his first formula describing the natural laws regarding the movement of pendulums. Although he never completed his schooling, Galileo served as the head of the mathematics departments at the Universities of Pisa and Padua, where he conducted a series of experiments on the speed and acceleration of falling objects, including his famous climb to the top of the Leaning Tower of Pisa to prove that objects of different weights dropped from its height would reach the ground at the same time.

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Galileo's "cannocchiali" telescopes at the Museo Galileo, Florence. (Sailko/Wikimedia Commons)

Galileo's Telescope

Galileo didn't invent the telescope, but he greatly improved upon its design. The first telescope he built in 1609 was more powerful than any before, and the next year, he discovered four celestial objects orbiting Jupiter that he assumed were stars but were in fact the planet's four largest moons. He also observed details on the surface of Earth's moon and numerous stars he'd never seen before, publishing his findings in a book called The Starry Messenger.

Galileo understood the importance of wealthy patrons, so he used The Starry Messenger to kiss up to the powerful Medici family by suggesting that the newly observed star cluster be named the Medician Stars. As a result, Cosimo Medici named Galileo the official philosopher and mathematician of the Medici family, and his association with them gave him a platform to advance his scientific theories.