‘Galileo showing the Doge of Venice how to use his telescope’, fresco by Giuseppe Bertini (1825-98).

  • Birth and family
  • Education
  • Stardom
  • Heresy

Birth and family

Galileo Galilei was born in Pisa, Italy, on 16th February 1564. From an Anglo-centric point-of-view, that was the sixth year of the reign of Queen Elizabeth I. William Shakespeare was born a couple of months later, on or about 23rd April.

Horoscope drawn up for himself by Galileo.
Horoscope drawn up for himself by Galileo.

According to Vincenzio Viviani (1622-1703), Galileo’s last pupil and early biographer, ‘his parents were then living there [in Pisa] for family business. His father was Vincenzio di Michelangelo Galilei, a gentleman very adept in mathematics and, especially, in the theory of music [musica speculativa]… He had more children of Signora Giulia Ammannati his wife, but Galileo was the oldest of his sons.’

By that time Pisa was part of the Duchy of Tuscany, and ruled from the capital Florence by the able, ruthless Duke Cosimo I de’ Medici.


The Leaning Tower of Pisa. Photo by Yeo Khee on Unsplash

The Galilei were an old established Florentine family, albeit now seriously impoverished. Nonetheless, Galileo received an extensive classical and scholastic education. From 1581 to 1585 he studied at – well, at least he attended – the university of Pisa. His father intended his eldest son to become a doctor, but Galileo left without taking a degree. After several intriguing ‘gap’ years – in which my novel Galileo’s Revenge is set – Galileo managed to secure a full-time job as a professor of mathematics, first in 1589 at Pisa and then in 1592 at the more prestigious university of Padua. At that time, mathematics was generally regarded as a fairly humble discipline, certainly as compared to philosophy or medicine.


Waning half Moon. NASA on Unsplash.
Photo by NASA on Unsplash

It wasn’t until 1609, aged 45, that Galileo got his big break. Having reverse-engineered (or maybe just stolen) the secret of the newly-invented telescope, he turned it upon the night sky. Within a couple of months he rushed into print with the Starry Messenger (Sidereus Nuncius). This slim volume describes his observations of mountains on the Moon, of the Milky Way and, above all, of the previously unknown moons of Jupiter. It was his ticket to lavish patronage by the most powerful courts at Florence and Rome. He was soon the most famous scientist in Europe.


Galileo spent the next two decades engaged in often bad-tempered polemics defending and extending his astronomical discoveries.

‘Galileo facing the Roman Inquisition’, after Cristiano Banti (184-1904). Wikimedia Commons.

Eventually, in 1632, he published his Dialogues upon the Two Chief World Systems (Dialoghi ). In this fat but readable tome he champions the still-contentious Copernican theory that made the Earth orbit around the Sun (rather than vice versa). Unfortunately, he had misread the mood of the Vatican, and the Roman Inquisition judged him to be ‘vehemently suspected of heresy’. He was forced to repudiate his Copernican beliefs and condemned to house arrest outside Florence for the rest of his life.

Free fall

Francis J Rowbotham, Storylives of Great Scientists (NY, 1918)

There was a silver lining however. In his humiliated isolation Galileo finally got around to publishing the Discoures on Two New Sciences (Discorsi). This more technical work explains his much earlier findings in mechanics – such as the uniform acceleration of falling bodies, the parabolic paths of projectiles, and the isochronicity of the pendulum (which lead him to design the first pendulum clock). He died in January of 1642. Newton was born the following Christmas.

Potted nutshell

Galileo Galilei, Italian astronomer and scientist. Born Pisa, 1564. Discovered moons of Jupiter with telescope in 1610. Condemned for heresy by Inquisition in 1633. Died Florence, 1642.

Further reading

J L Heilbron, Galileo (OUP, 2010).

Galileo’s Astrology, ed. Nicholas Campion and Nick Kollerstrom (a special issue of Culture and Cosmos, vol 7 no 1, Spring/Summer 2003).