What was Galileo Galilei ?

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Galileo Galilei was born in Pisa, Italy, on the 15th of February 1564, he died on the 8th of January 1642.

Galileo was a ground breaking astronomer, physicist, mathematician, philosopher and inventor. Among his inventions were telescopes, a compass and a thermometer.

Galileo enrolled to do a medical degree at the University of Pisa but never finished, instead choosing to study mathematics.

Galileo built on the work of others to create a telescope with around 3x magnification, he later improved on this to make telescopes with around 30x magnification.

With these telescopes, Galileo was able to observe the skies in ways previously not achieved. In 1610 he made observations of 4 objects surrounding Jupiter that behaved unlike stars, these turned out to be Jupiter’s four largest satellite moons: Io, Callisto, Europa and Ganymede. They were later renamed the Galilean satellites in honor of Galileo himself.

The discovery of these moons was not supported by the scientific principles of the time and Galileo had trouble convincing some people that he had indeed discovered such objects. This was similar to other ideas put forward by Galileo that were very controversial at the time.

Considered the father of modern science, Galileo Galilei (1564-1642) made major contributions to the fields of physics, astronomy, cosmology, mathematics and philosophy.

The Geocentric model of the universe which was embraced by earlier astronomers had the Earth at the center of the universe with other objects moving around it. Work by Galileo, Nicolaus Copernicus and Johannes Kepler helped to supercede this theory with the more accurate heliocentric model.

He invented an improved telescope that let him observe and describe the moons of Jupiter, the rings of Saturn, the phases of Venus, sunspots and the rugged lunar surface.

Galileo refused to believe Kepler’s theory that the moon caused the tides, instead believing it was due to the nature of the Earth’s rotation (helping prove that even the smartest people can make mistakes).

His flair for self-promotion earned him powerful friends among Italy’s ruling elite and enemies among the Catholic Church’s leaders.

Famous Galileo quotes include: “In questions of science the authority of a thousand is not worth the humble reasoning of a single individual.”

His advocacy of a heliocentric universe brought him before religious authorities in 1616 and again in 1633, when he was forced to recant and placed under house arrest for the rest of his life.

Galileo Galilei was born in Pisa in 1564, the first of six children of Vincenzo Galilei, a musician and scholar.

“Alas! Your dear friend and servant Galileo has been for the last month hopelessly blind; so that this heaven, this earth, this universe, which I by my marvelous discoveries and clear demonstrations had enlarged a hundred thousand times beyond the belief of the wise men of bygone ages, henceforward for me is shrunk into such a small space as is filled by my own bodily sensations.”

In 1581 he entered the University of Pisa to study medicine, but was soon sidetracked by mathematics.

Galileo was the first of six children born to his parents in a Roman Catholic family. From the beginning of his career, he was intelligent and talented.

In 1583 he made his first important discovery, describing the rules that govern the motion of pendulums.

Galileo seriously considered priesthood at a very young age.  However, Galileo’s father wanted him to study medicine at the University of Pisa, for which he enrolled but never completed.

Did you know? After being forced during his trial to admit that the Earth was the stationary center of the universe, Galileo allegedly muttered, "Eppur si muove!" ("Yet it moves!" ).

In 1585, Galileo had to leave the University of Pisa due to financial concerns. However, he later joined the university as a professor in 1589.

The first direct attribution of the quote to Galileo dates to 125 years after the trial, though it appears on a wall behind him in a 1634 Spanish painting commissioned by one of Galileo's friends.

Galileo’s contract with the university was not renewed because Galileo was difficult to work with, and, perhaps, because of his inappropriate behavior with his students. Thus, once again he had to leave the University of Pisa and find employment elsewhere.

From 1589 to 1610, Galileo was chair of mathematics at the universities of Pisa and then Padua.