Galileo Galilei

**Galileo Galilei** (15 February 1564&nbsp;– 8 January 1642) was an Italian polymath. He was a professor of mathematics and natural science in Padua and Pisa. People most remembered him today for his conflict with the Catholic Church of his day, which led to his trial for heresy by the Inquisition.

## Life 
Galileo was born on 15 February 1564 in Pisa, Duchy of Florence. He was the eldest of five siblings. His father was Vincenzo Galilei, who was a scholar and a musician.  In 1574, the Galilei family moved to Florence and he started his formal education in the Camaldolese monastery.
### Astronomy 
Galileo was not the first person to build a telescope. He was the first person to publish his observations of astronomical objects through a telescope. He discovered that the Milky Way is made of many stars. He discovered that the Moon has hills.

### Publications 
The most important are:
* *Sidereus nuncius* (starry messenger). Venice 1610. Discovery of 'new worlds' with the telescope.
* *Dialogo sopra i due massimi sistemi del mondo, Tolemaico e Copernicano*. Florence, 1632. The famous 'dialogue between two world systems, Ptolemaic and Copernican'.
* *Discorsi e dimostrazioni matematiche, intorno a due nuove scienze*. (discourses and mathematical demonstrations relating to two new sciences) Leiden 1638. This, on kinematics, a non controversial subject, was written when Galileo was under house arrest, and published in Holland, out of the Inquisition's territory.

### Trial for heresy 
Galileo came to accept the findings of Copernicus, that the Sun was the center of the then-known universe, and not the Earth. He played a major part in the scientific revolution through this argument. Because he promoted this and other ideas, he came to the notice of the Committee of Propaganda, the dreaded Inquisition. The Church taught that the Earth stood still, while everything in the sky moved around it. The Inquisition ruled in 1616 that other theories could only be discussed as possibilities, not facts. Galileo said he would obey. 

Galileo later discussed the question in his most famous work, *Dialogue Concerning the Two Chief World Systems*, published in 1632 by permission of the Inquisition. His scientific writing was usually in Latin for hundreds of scientists around Europe, but this was one of the books he wrote in Italian so thousands of Italians could read it. The book was in the form of conversations between three men. The man representing the Church's point of view was called 'Simplicio'.

Church leaders who liked his earlier books were angry at this one. The Inquisition took action in 1633. He was arrested and put on trial. They found him "vehemently suspect of heresy". They reminded him of the fate of Giordano Bruno, who had been burnt at the stake for heresy on topics such as transubstantiation and the Trinity. Bruno also believed the Earth went round the Sun and stars had planets. The Inquisition forced Galileo to recant (say he was wrong) under the threat of execution, and to withdraw his works from publication. Galileo spent the last ten years of his life under house arrest. Galileo continued to write about physics and other topics, but not astronomy.

Galileo has become synonymous with a warrior for scientific truth. Although he had to retract his writings at his trial, it is widely believed that after the trial he insisted that Earth does move around the sun, saying the famous phrase "*Eppur si muove*' – *still it moves.* The saying itself became a slogan for science.

## Death 
Galileo Galilei died on  in Arcetri, Grand Duchy of Tuscany, Italy.

Previously, he was buried in a small room next to the novices' chapel at the end of a corridor. Later, he was reburied in the main body of the basilica in 1737 after a monument had been built there in his honor.

## Related pages 
* Giordano Bruno
* Nicolaus Copernicus
* Johannes Kepler
* List of science books of 17th century
* Speed of light
* Michelson–Morley experiment

## Notes 
## References 
## Bibliography 
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