13 Facts About Galileo Galilei

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Einstein once said that only the work of Galileo can be seen as the real beginning of astronomy and physics. All before that might have been science but not in a way, we are thinking about that term today. Galileo was the first person pointing a telescope to the sky and making incredible observations about our cosmos.

He discovered several bodies in our solar system, spotted sunspots and that the sun rotates and even confirmed the fact that all planets are moving on orbits around the sun but not the earth. Especially this last discovery led him into serious trouble with the Catholic Church and eventually led to a sentence for house arrest to the end of his life.

As his life was so amazing and he changed the way we think about physics so heavily we want to share with you 13 facts about Galileo you definitely need to know.

1. Galileo Galilei has spent ten years under house arrest.

Shortly after Galileo published his book “Dialogue Concerning the Two Chief World Systems” in 1632 he was sentenced by the Roman inquisition to imprisonment. Already one day later this was commuted to house arrest. The last ten years of his life he spent at his villa in Arcetri, near Florence. During that time, it was prohibited for him to publish any books and the people allowed to visit him were strictly restricted. He even was ordered to read the seven penitential psalms once a week for the next three years.

Portrait of Galileo Galilei around 1605.
Portrait of Galileo Galilei around 1605.

Nevertheless, Galileo received several visitors from Europe including poet John Milton and philosopher Thomas Hobbes. On one occasion Galileo was able to smuggle out his manuscript for his latest book “Discourses and Mathematical Demonstrations Relating to Two New Sciences” (see the original text here), which is considered as one of his finest work. It was published in 1638 and was Galileo’s final book. In the same year, Galileo went completely blind and died on 8 January 1642, aged 77.

2. Both of Galileo’s daughters became nuns.

Galileo Galilei never married but still had three children with his housekeeper Marina Gamba. Because of their illegitimate birth Galileo did not consider his daughters as marriageable and therefore placed them in a convent in Arcetri, where both of them remained there for the rest of their lives.

Portrait of Galileo's first daughter  Maria Celeste.
Portrait of Galileo’s first daughter Maria Celeste.

Galileo kept a close relationship with his oldest daughter who took the name Maria Celeste upon entering the convent. She eventually died on 2 April 1634 and was buried with his father at the Basilica of Santa Croce in Florence. Galileo’s younger daughter Livia became known as Sister Arcangela but was ill for most of her life. Only his son Vincenzo was later legitimized as his legal heir although both never had a close relationship.

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3. Galileo was sentenced to imprisonment by the Roman inquisition.

During the time of Galileo, the so-called “Geocentric model” was widely accepted. This model was developed by Greek astronomer Claudius Ptolemäus and claimed the Earth as the center of the universe. When Nicolaus Copernicus came out with his idea that not Earth but the Sun is the center of the universe the Catholic Church declared the Copernican theory as heretical.

A painting showing Galileo facing the Roman Inquisition by Cristiano Banti.
A painting showing Galileo facing the Roman Inquisition by Cristiano Banti.

Copernicus’ theory was just in too strong contrast with statements of certain Bible verses and as Galileo did provide proof for Copernicus’ theory, he also became part of a catholic investigation.

Due to his reputation, Galileo was not arrested and even received permission from the Catholic Church to continue his investigation on Copernicus’ ideas however he was not allowed to publish anything that would defend these theories.

When Galileo published his book “Dialogue Concerning the Two Chief World Systems” (see the original text here) in 1632 it was created as a dialogue between two philosophers comparing the Copernican system with the Ptolemaic system. The Catholic Church saw this book as Galileo’s try to support the Copernican model and ordered him to stand trial in front of the inquisition in Rome. He was found “vehemently suspect of heresy”, was sentenced to life in prison and his book was banned.

4. Galileo lost three of his fingers almost one century after he died.

This fact about Galileo Galilei seems a bit strange as one might be questioning how an almost 100-year-old corpse can lose three fingers. The reason for that is that in 1737, almost 100 years after Galileo’s death, his body was exhumed from a side chapel at the church of Santa Croce in Florence to transfer his remains to the church’s main basilica. While doing so one of Galileo’s admirers removed three fingers and a tooth from his body.

Galileo' middle finger at the Museo Galileo in Florence.
Galileo’ middle finger at the Museo Galileo in Florence.

Although it is not clear who exactly took the fingers and the tooth from Galileo, historians assume that these body parts were handed down through generations of the admirer’s relatives. At one point in time the items were thought to be lost forever however in 2009 they appeared again during an auction. The private collector was able to deduce their origin and has returned at least Galileo’s middle finger to the authorities. It’s currently on exhibition at the Museo Galileo in Florence, Italy.

5. Galileo’s father was a very important musician during his time.

Vincenzo Galilei, Galileo Galilei’s father, was an important composer and music teacher during the final years of the renaissance. With his music, he significantly contributed to the transition to the Baroque era. Several of his compositions have survived and you can still listen to it.

He also taught Galileo to play the lute and his sense of music might have aided in Galileo’s scientific work. Even without clocks, Galileo was always able to time rolling and falling objects to within mere fractions of a second.

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6. The Catholic Church didn’t admit that Galileo was right until 1992.

It’s been a long way since Galileo Galilei was found “vehemently suspect of heresy” and sentenced to life in prison by the Catholic Church in 1632. Only in 1979 an investigation on the Church’s condemnation of Galileo was initiated by Pope John Paul II.

It took them 13 years or even 359 years since Galileo was sentenced to imprisonment to find a conclusion. In 1992 the Catholic Church closed their investigation and released a formal apology. The statement placed most of the blame on the clerks who worked on Galileo’s case during that time but not on Pope Urban VIII, who presided over the trial. Also, the charge of heresy was never overturned.

7. It is very unlikely that Galileo Galilei really dropped anything off the leaning tower of Pisa.

Galileo has spent his early life and career in Pisa so the famous tower in Pisa might be a perfect match to test his theories of motion and falling bodies. However, there is only one written account of Galileo performing some kind of experiment close to what the common myth says.

If it’s true and Galileo really dropped a small and a large bullet from the top of the tower in Pisa it would have been probably such a grand spectacle that there would be more documentation about it. As this is not the case it’s highly unlikely that Galileo dropped anything from the leaning tower of Pisa.

8. Galileo Galilei wrote about general relativity long before Einstein did.

It seems obvious that this fact about Galileo does not say that Galileo discovered the general theory of relativity long before Einstein did but nevertheless, he had some similar thoughts on that topic as Einstein almost 300 years after him. Like Einstein Galileo was also thinking that the term movement might differ based on your personal perception.

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If you are standing in a windowless cabin on a ship Galileo proclaimed that you would have no chance to tell if this ship is moving at a steady speed or if it is motionless. That’s exactly the same thought Einstein had when thinking about his general theory of relativity.

If you like to learn more about this topic, we can highly recommend our article about 15 facts about Einstein. Definitely worth reading especially if you are into science.

9. There was a spacecraft named “Galileo”

In 1989 NASA launched the space shuttle Atlantis delivering the spacecraft “Galileo” into orbit. The spacecraft was developed to study the planet Jupiter and several of its moons, as well as also some other bodies in our solar system. Galileo arrived at Jupiter on December 7, 1995 and became the first spacecraft to orbit Jupiter.

Picture of Jupiter moon Europa by the spacecraft "Galileo".
Picture of Jupiter moon Europa by the spacecraft “Galileo”. Source: NASA.

It is no coincidence that NASA took the name of Galileo Galilei for a spacecraft studying Jupiter as also Galileo himself dedicated a huge part of his life to exploring this planet and its moons.

The mission came to an end in 2003 when NASA crashed the spacecraft intentionally into Jupiter to eliminate the risk of the spacecraft to collide with Jupiter’s moon Europa and contaminating any potential life there.

10. Galileo was a college dropout.

Galileo’s father Vincenzo Galilei was not a scientist as his son would later become but a music theorist born in Pisa, Italy. Although Vincenzo was born in a noble family, he never was wealthy. Due to that fact, Vincenzo never wanted his son to live in poverty and indigence. When Galileo approached him with the idea to become a monk, he, therefore, refused his proposal and enrolled him at the University of Pisa to study medicine.

A portrait of Galileo by Justus Sustermans, 1636.
A portrait of Galileo by Justus Sustermans, 1636.

Galileo however was never really into medicine but rather more interested in mathematics and astronomy, so he shifted his focus to these two subjects. In 1585 Galileo eventually left school without earning a degree and continued his studies on his own. To finance these studies, he gave private lessons and turned back in 1589 to the University of Pisa to teach math.

11. Galileo Galilei didn’t invent the telescope.

Although Galileo is often named as the inventor of the telescope, he actually just improved it but did not have the idea from scratch. Instead, the Dutch eyeglass maker Hans Lippershey can be credited with the creation of the telescope.

At least this is what the earliest record of the telescope says. Lippershey tried to patent his idea for the device in 1609 but with no success as it was too easy to copy in the eyes of the Dutch government.

In the same year, Galileo learned about the device and developed his own telescope by improving Lippershey’s idea significantly. Soon, he had a telescope that could magnify 20 or even 30 times. He started to point the telescope at the moon and became the first person to realize that this astronomical body is full of craters and mountains against the common belief that it had a smooth surface.

The Moon as drawn by Galileo Galilei on the left side and and photographic image on the right side.
The Moon as drawn by Galileo Galilei on the left side and and photographic image on the right side.

With this new device, Galileo was also able to discover certain other astronomical bodies like the moons orbiting Jupiter and Venus or the fact that these planets are moving on definite orbits.

All these discoveries made Galileo famous in a very short period of time and even led to his appointment as a chief mathematician to the grand duke of Tuscany as well as a chief mathematician at the University of Pisa.

However, one of the greatest facts about Galileo and his discoveries with the telescope was that he provided the proof for the theory of Polish mathematician Nicolaus Copernicus that not Earth but the Sun is the center of the solar system. A groundbreaking idea during that time.

12. King Louis XIV asked Galileo to discover new planets in the name of France.

When Galileo discovered Jupiter and four of its moons in 1610, he immediately rose to fame. He called the moons the “Medicean stars” to honor his patron Cosimo II from the Medici family who ruled over Tuscany in Italy. As soon as the news spread across Europe King Louis XIV from France was asking Galileo if he could also name further planets he might discover after him. Galileo never did.

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13. The similarity between Galileo’s first name and last name is no coincidence.

During the days of Galileo’s lifetime people in the Italian region of Tuscany used to name their first-born son after the family’s last name. As Galileo was the first of six children in his family, he got the pleasure to receive the name of his family as his first name.

However, there might also be another explanation that Galileo’s first name echoes his last name. According to another common theory Galileo might also be named after a famous ancestor of his family – Galileo Bonaiuti

We hope you enjoyed our 13 facts about Galileo as much as we did. His impact on physics and astronomy was incredible and changed our understanding of mankind in our universe although it took several hundred years until we understood it correctly. If you know even more facts about Galileo please leave us a comment and we will add your facts to our list. If you are looking for even more fun facts follow us on Facebook, Instagram, Twitter, or Pinterest. You can also have a look into our general Fun Facts section or in our section dedicated to facts about certain people if you want to read similar articles like that.


Hi I'm Robby and I started this website in 2019. My aim is to share with you all the amazing and unbelievable fun facts I found out during my daily life. I hope you enjoy these fun facts as much as I do and hope that you like my website the same way.

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