Galileo Galilei

Galileo Galilei (1564–1642) was a brilliant Italian scientist, mathematician and astronomer. He was one of the first scientists to show that the Sun (rather than the Earth) is at the centre of our solar system, revolutionising our understanding of space. He also invented a new type of telescope, thermometer and compass. But Galileo’s life was not easy. Find out more about this ‘father of modern science’ and use our printable resources below to test your knowledge.

Fun Facts:

• Galileo had many talents – he was also a great musician! He followed in his father’s footsteps and played the lute very well.
• Galileo’s name has been honoured in many scientific enterprises, including the Galileo spacecraft (which studied Jupiter) and Galileo (a satellite navigation system). The Galilean moons of Jupiter are also named after him.
• When Galileo was reburied in 1737 to an honorary tomb, some admirers took three fingers and a tooth from his body. These have been preserved and are now on display at the Galileo museum in Florence, Italy.

Galileo Quotes

“You cannot teach a man anything; you can only help him find it within himself.”

“All truths are easy to understand once they are discovered; the point is to discover them.”

“Mathematics is the language with which God has written the universe.”

A Short Biography of Galileo Galilei

Galileo Galilei was born in Pisa, Italy, in 1564, the first of six children born to Vincenzo Galilei and his wife Giulia. Galileo’s father was a famous musician and composer.

When Galileo was 10, his family moved to Florence and he went to school at the nearby Camaldolese Monastery. As a young man, Galileo thought he wanted to become a priest but he later followed his father’s wishes to study medicine at the University of Pisa.

Galileo was fascinated by the world around him. During his student days, for example, he watched a cathedral chandelier swinging in the breeze. He compared the movement to his heartbeat and noticed that the chandelier took the same amount of time to swing back and forth, however far it swung. He tested out this theory at home, using two pendulums of equal length. When one swung with a large sweep and one with a small sweep, they kept time together.

With an increasing interest in science, Galileo persuaded his father to let him study mathematics and natural philosophy, instead of medicine. Galileo later taught mathematics at the University of Pisa, as well as the University of Padua.

Galileo began developing other mathematical theories about motion. He proposed that objects of the same size fall to the ground at the same speed regardless of their mass, and that they steadily accelerate. Every time Galileo came up with a new theory, it was difficult to persuade people of his views. But this just spurred Galileo on! He became one of the first scientists to repeat experiments again and again to prove the worth of his principles. His ‘scientific method’ of proving a hypothesis is now widely used in science today.

Galileo is perhaps most famous for his controversial view that the Sun, rather than the Earth, was the centre of our Universe. Today, we know that the Sun is actually the centre of our solar system and that the Universe is even bigger still.

In 1609, Galileo developed a more powerful telescope that increased magnification from 3x to 30x, helping to see further into space than ever before. Galileo supported the theory of Polish scientist Nicolaus Copernicus (who died before Galileo was born) who had suggested the Earth revolves around the Sun. Galileo observed the phases of Venus as it orbits the Sun, was the first to see Jupiter’s moons, and to see the difference between planets (which appeared as small discs) and stars (which appeared as points of light). He also discovered that our own moon is covered in craters. Galileo published many of his observations in a scientific paper called ‘The Starry Messenger’ in 1610, and later wrote a book explaining his views.

Galileo’s findings were very controversial at the time, and were greatly opposed by the Catholic Church, who believed the Earth was the centre of the Universe. In 1633, he was put on trial for his views and found guilty of heresy (opposing the views of the church). He was sentenced to life imprisonment, but served most of his sentence at home under house arrest. Although Galileo was forbidden to write or teach about his work, he kept on working and studying, even when he went blind in later life. Some of his booklets were secretly sent to other European countries.

Galileo never married but had three children (Virginia, Livia and Vincenzo) with a woman called Marina Gamba. His two daughters became nuns. After his death in 1642, at the age of 77, the Catholic Church expressed regret at Galileo’s treatment – although he wasn’t officially pardoned until 1992!

Our Galileo Galilei Resources