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Galileo Galilei


The Father of Physics and Astronomy


Galileo was born in Pisa in February, 1564.  He was the oldest of six children.  His mother was called Giulia and his father was a musician called Vincenzo.  The family surname was Galilei. 

The family had chosen their surname Galilei two hundred years earlier in the late 1300s in honour of their well-known ancestor called Galileo Bonaiuti - who was a medical doctor in Florence.   It could be that Galileo was named in honour of his ancestor.

This means that Galileo's first name was the same as his surname!  An equivalent in English would be William Williams, Robert Roberts, etc.

How intriguing that, in the same family, two people named Galileo were brilliant scientists!  There must have been something in the name and in the family blood!


Above: some drawings of the moon's phases,  by Galileo.


Galileo had a Christian education and considered becoming a priest but instead he went to Pisa University to study Medicine.   However, he decided that he did not wish to become a doctor and instead he chose to study mathematics.

In 1591, Galileo became a teacher of Geometry and Astronomy at the University of Padua (Padova in Italian).  During this period, he made lots of very important scientific discoveries.   For example, he made a telescope to observe the sky and he discovered the moons of Jupiter.  That is why the moons of Jupiter are named 'the Galilean satellites.'

Originally, Galileo named the four moons of Jupiter
'the Medicean satellites' in honour of his patron, the Grand Duke of Tuscany, who belonged to the De' Medici family.

Galileo also observed the planets Venus, Saturn and Neptune, sunspots, the moon's craters and mountains, comets, the tides of the sea, the Milky Way and other distant stars. 

He made calculations about the speed of light and the weight of air. 

In 1623, he published a book about his theories and observations.  This book is called The Assayer (Il Saggiatore in Italian.)


Galileo also made a microscope, thermometer and a pendulum clock.  He liked to conduct experiments, especially to observe the movement of objects.  It is said that he would drop objects of varying weight from the Leaning Tower of Pisa in order to observe the speed of their fall and to prove that those that fall more slowly do so due to air resistance. 

In Italian the leaning tower is called la Torre Pendente di Pisa.

In 1633, Galileo was accused of heresy by the Catholic Church because of his experiments and theories.  Galileo's correct theory that the planet Earth moves around the sun was the opposite to the Christian teaching of the time.  In those days, it was incorrectly taught that the sun moved around the Earth and that the Earth stood still and was at the centre of the universe!

Galileo was tried by the Catholic Church and found guilty of heresy.  He was forced to state publicly that his theory that the planet Earth moved around the sun was untrue, otherwise he faced execution.  Then, he was imprisoned (kept under house arrest) in his villa in Florence for the rest of his life.  That villa is called Il Gioiello meaning - the jewel.

During the time of his imprisonment, he continued to study and he wrote some of his most famous work.  In fact, he is often called 'The Father of Modern Physics' because of the important scientific work he did whilst imprisoned. 


Above is a famous painting by Cristiano Banti depicting part of the trial of Galileo.

Although Galileo never married, he had three children.  Two girls and a boy.  When the girls were young teenagers, they were sent to live in a convent as nuns.  They lived there for the rest of their lives.  Galileo felt that he would be unable to find good husbands for them because they had been born out of wedlock.  The only option for them was to live a religious life in a convent. 


Galileo's oldest child was called Virginia and she was very special.  She loved her father dearly. 

When she became a nun she chose a new name for herself - Maria Celeste.  'Celeste' means 'heavenly' and 'belonging to the sky'.  She chose this name in honour of her father's love of the sky and astronomy.

The villa where her father was kept under house arrest is next door to the convent where she lived.  He rented the villa so that they could be close.

Maria Celeste was very intelligent, like her father.  She loved to study medicine and made herbal remedies for the sisters of the convent and for her father.  She became the convent's pharmacist.  It is also believed that she helped her father to write his books and that she wrote hundreds of letters to him. 

She died from dysentry at the age of thirty-four.  A crater on the planet Venus has been named Maria Celeste in her honour.

Galileo's younger brother - Michelagnolo Galilei (1575-1631) - was also very intelligent.  He was a famous musician and composer.

Galileo died at his home in January, 1642.  His tomb can be visited in La Basilica di Santa Croce in Florence.

On 31 October, 1992, Pope John Paul II officially apologised to Galileo for how he had been treated by the Catholic Church.


Above is an image of Galileo's tomb.  Below is an image of some old Italian bank notes in Lire, depicting Galileo and his work.


Grazie, Galileo, per tutto il tuo lavoro fantastico! 
Thank you, Galileo, for all your fantastic work!

Grazie mille!

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