Galileo Galilei: A Legendary Astronomer

Those were the days when mankind was oblivious to the grand design of the solar system and the place of our watery planet in the vast expanse of the cosmos. It was then that the bold efforts of Galileo Galilei unfolded to us the many mysteries of Nature. Using a telescope of his time, Galileo made our understanding of the planets of the solar system and their satellites more clear. For example, he had seen mountains and plains on the Moon, just like those on Earth. All this and much more were revealed in a book, The Starry Messenger, which appeared in March 1609. To read more scientists’ biographies read – Hindi Science Blog

Galileo had set the ball rolling for new scientific revolution based on mathematical applications in Physics. He put forth the idea of ‘acceleration’ as a mathematically defined concept. This enabled him to demonstrate the law of falling bodies, which became the foundation of the concept of dynamics. Although Newton later provided a better understanding of the forces that cause bodies fall, and that holds the entire system together, it was Galileo’s dynamics, however elementary, that remained the foundation of classical mechanics.

Photo by James Frid

By the time of Galileo, the 2000- years old tradition of Aristotelian science was already breaking down. This had become possible after Nicolaus Copernicus realized that the Earth is a planet and not the center of the Universe. Galileo tried the trust Copernican theory upon the general public. By recording his observations with a newly invented telescope, Galileo launched a new branch of astronomy that studied the features of the celestial bodies.

In 1951, with the death of his father, Galileo troubled with the duties of the head of the family. His salary hardly matched this responsibility, as what he earned was just about one-thirtieth of that of a professor of medicine. Besides, Galileo had made enemies in the faculty by writing a satirical poem poking fun at the academic gown, which university staff was expected to wear at all times.

In 1592, he obtained a better post of teaching mathematics at the University of Padua that raised his salary three times. He also added to his income by taking in students for extra tuition. As students mainly wanted mathematics for military engineering or navigation, Galileo designed a new type of instrument, the ‘military compass’.

Galileo never married but entered into a relationship with a woman named Marina Gamba. They had three children who eventually joined Galileo when their mother wed. His eldest daughter, Virginia, was very close to him. In later years he leased a house to be near her nunnery in Arcetri, outside Florence. Galileo left Padua in 1610.

Laws of Pendulum

Galileo discovered the law of pendulum by rational thinking that the tiny metal sphere tied at the end of a string would oscillate in equal times, through very small arcs, depending only on the length of the string. He recognized that all motion is natural, and any force, however slight, can set a body in motion. Further, once a body begins to move, it continues to move until some other force brings it to a halt. Later Isaac Newton discovered the concept of inertia on similar arguments.

Galileo also showed that if the vertical acceleration of a falling body is combined with horizontal motion, the resultant path of the body is a parabola. He showed that any projectile would move in a parabolic path. This forms the basis of ballistics, a principle used in gunnery and rocketry.

Heliocentric Cosmos

Galileo built a new design of the telescope in 1609, which could magnify telescope in 1609, which could magnify nine times. For this, he was given life tenure of his chair at Padua and a large salary hike. Further, Galileo invented another telescope magnifying 30 times and with it he observed heavenly bodies in the sky. His results were revolutionary and were published in the book, “The Starry Messenger” in 1610.

Some of the revelations were that the Milky Way is composed of separate stars; there are valleys, mountains, and craters on the Moon, and Jupiter has four orbiting satellites. The first finding demonstrated that there was more to be discovered about the Universe. The second finding showed that Aristotle was wrong in claiming that celestial bodies were unblemished globes different from the earthly bodies. While the third disproved the argument that the Moon would be left behind if the Earth orbited the sun.

Galileo also discovered that the planet Venus shows phases parallel to those of Moon, which again was evidence against ancient teaching. However, these explanations convinced him that the Copernican Heliocentric Theory of Universe was correct.

However, before Nicolaus Copernicus (1473-1543), who proposed the heliocentric theory, Pythagoras and Philolaus too had taught that the Earth is not fixed in space but rotates on its axis every 24 hours, thus causing the change of day and night.

Church and Inquisition

Galileo was enforced to deny his acceptance that the Earth moves around the Sun. After reluctantly saying that the Earth does not move around the Sun, Galileo is apparent to have muffled under his breath. Naturally, for his courageous standing against the church, he was tried by the inquisition in 1663. Galileo was condemned to spend the rest of his life restricted to his country house at Arcetri. In 1634, his daughter Virginia died at the age of 33 leaving Galileo deeply scared. In 1637, he went blind.

Galileo died in 1642, the world remembers him even today as he had the courage to maintain to the very end that it is the Earth that revolves around the Sun. Evangelista Torricelli, his student, was truly able to learn from him and develop his ideas further. In 1922, the church admitted that Galileo had been right in supporting the theories of Copernicus.

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