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Galileo Galilei Biography

Biography | 7-14 yrs | Reading Pod, Interactive

After reading this article, whenever you will gaze at the shining stars on a dark night, one name that will immediately come to your mind will be that of Galileo. Galileo was a famous Italian astronomer, mathematician and physicist born in Italy, in the year 1564. Galileo thought ahead of his times and gave the world new horizons in the fields of Astronomy and Physics.

Galileo Galilei : Facts and Information

  • His father Vincenzo Galilei was a musician and his mother was Giulia Ammannati.
  • When he was a child, he loved assembling different kinds of objects and making them into motorized toys.
  • He was always curious about what the stars were. People thought they were stuck on the Earth’s holes.
  • He had started to study medicine before becoming fascinated with Aristotle. He later questioned Aristotle’s theories. In 1589, Galileo joined the University of Pisa where he taught Geometry, Mechanics, and Astronomy to the students. Since he did not have a good rapport with his colleagues, he quit the University of Pisa and joined the University of Padua where he made many of his amazing discoveries in the field of Astronomy and Physics.

Galileo Galilei : Invention & Contributions


He was observing the lamp hung by a string at the Cathedral of Pisa, and saw that no matter how long the string was, the time of swinging was always the same. This became Galileo’s pendulum law.

He then discovered all objects fell at the same time from the same height irrespective of their weight. This contradicted Aristotle’s theory which stated that heavier objects fall at a faster speed from a height than lighter objects. Galileo, however, could not publish his results.


Galileo had seen a Dutch inventor invent the spy glass which made things from far appear closer. Galileo used this concept to invent the telescope in 1609. It was made of iron, wood, cardboard and leather with a height of 200 mm and a diameter of 55 mm. He fixed two lenses into a tube and effectively magnified the images of far-off objects.


  • Almost 400 years back, everybody believed that the Earth sat at the center of the universe, while the other heavenly bodies revolved around it. This theory was known as geocentric theory and was also supported by the Church. Those who did not agree with this theory and tried to refute it were punished by the Church. Galileo argued that the sun was at the center, not the Earth. This was a path breaking discovering and known as the heliocentric model. He proved Copernicus’s theory that the earth revolves around the sun and not vice versa.
  • Equipped with his highly advanced telescope, he focussed his attention towards the sky and started breaking several myths about the universe that existed in the society at that time. He discovered that the moon was not a perfectly round ball and had mountains and craters.
  • He used to observe the planets very keenly and it came to his notice that there were certain ‘lobes’ around the planet Saturn. We now know these lobes as the “rings of Saturn.”
  • Galileo is also credited with the discovery of the sunspots.
  • Gaileo saw that there were four objects that revolved around the planet Jupiter. Upon further exploration, he saw that these were four moons that orbited around Jupiter- Io, Callisto, Europa and Ganymede. The discovery of these moons was against the scientific principles of the time and Galileo had a great deal of trouble convincing the other scientists. Much later after the discovery of these moons, they were renamed as Galilean satellites in the honour of Galileo.
  • Galileo proved that the moon did not cause tides; rather the earth’s rotation around the sun caused it. But this later was proven wrong.

The Geometric and Military Compass

This was designed to measure the height at which the cannon ball will be fired for accurate shots at the battlefield.

Objects Falling

  • Galileo discovered that objects of different weights would fall at the same time from the same length, irrespective of how heavier or lighter they are.
  • The Thermometer and the Hydrostatic Balance
    There weren’t any thermometers to measure heat. Galileo discovered that objects did not flow in water because of their heavy weight, but because of their density. A glass tube was filled with water and several bubbles; and attached to each bubble is a metal object of different weight. This gave each bubble a different density. When the temperature rises, the density of the water decreases. The bubbles with higher density would sink down and the bubbles with lower density would float on top.

Disobeying the Church:

  • The clergymen of those times felt threatened by the revolutionary work that Galileo was doing in the field of astronomy as it was in contrast with what they believed in and supported. And thus, in 1616, Galileo was called to Rome and warned not to teach or write about his experiments or any of his controversial theories. In 1623, a good friend of Galileo, Cardinal Maffeo Barberini, was chosen as the Pope. He permitted Galileo to pursue his work on astronomy and even encouraged him to publish it.
  • In 1632, Galileo published the ‘Dialogue Concerning the Two Chief World Systems’, which portrayed a discussion among three men: one who believed in Copernicus’ geocentric theory of the universe, one who argued against it, and one who was unbiased. Though Galileo claimed that he was not propagating any particular theory, it was clear that he was trying to persuade people in a subtle way to cast away their old beliefs and learn to accept all that was scientifically true.
  • Galileo’s view of the universe was clearly very different from the beliefs of the Catholic Church and he was thus, forced to withdraw many of his ideas and was taken into unofficial custody. Due to the rigid and orthodox mindset of the clerics, this brilliant scientist had to spend the final years of his life under house arrest. He, who deserved to be honoured and awarded for his ground breaking discoveries, was ostracized from the society and forced to live in isolation. Galileo silently left for his heavenly abode in Arcetr, Italy, on January 8, 1642, after suffering from a bout of high fever. There was a ban on reprinting Galileo’s work until 1718, but slowly after that, the new generation scientists started digging out his work and came out openly with the scientific truth associated with his theories. The world realized its mistake only after it had lost one of the genius scientists ever born.

Fun Facts about Galileo Galileio

  • A finger of Galileo is at display at The Museum of History in Florence.
  • Einstein was a big fan of Galileo.
  • Galileo’s works were published sixty years after his death.
  • Galileo sold his inventions to raise money for his illegitimate daughters’ dowries.
  • Galileo had once said, “In questions of science the authority of a thousand is not worth the humble reasoning of a single individual.” Who wouldn’t agree with this today? If only people in his times were broad minded enough to accept the scientific truth in Galileo’s theories, you never know, what all this great man could have discovered. His observations and scientific theories make the essential fundamentals of Astronomy and Physics today. It is for this reason, he is rightly known as the “father of modern observational astronomy.”