Biographies

Galileo and the telescope: the new astronomy

Galileo and the telescope: the new astronomy

Galileo is a fundamental character in the scientific and cultural revolution that occurred during the Renaissance.

The Italian mathematician, physicist, philosopher and astronomer Galileo Galilei (1564-1642) argued that the Earth revolved around the Sun, which contradicted the belief that the Earth was the center of the Universe.

He refused to obey the orders of the Catholic Church to stop exposing his theories, and was sentenced to life imprisonment. Together with Kepler, the scientific revolution that culminated in the work of Isaac Newton began. His main contribution to astronomy was the use of the telescope for the observation and discovery of sunspots, valleys and lunar mountains, the four major satellites of Jupiter and the phases of Venus.

In the field of physics he discovered the laws that govern the fall of bodies and the movement of projectiles. In the history of science, Galileo became the symbol of the fight against authority and freedom in research.

Galileo was born near Pisa on February 15, 1564. He studied with the monks in Vallombroso and in 1581 he entered the University of Pisa to study medicine. Soon he changed his studies for philosophy and mathematics, leaving the university in 1585 without having obtained the degree.

In 1589 he worked as a professor of mathematics in Pisa, where it is said that he demonstrated before his students the error of Aristotle, who claimed that the speed of falling of the bodies was proportional to their weight, dropping two objects from the leaning tower of this city of different weights.

Other important discoveries of Galileo in those years are the pendulum laws (about which he would have begun to think, according to the well-known anecdote, observing a lamp that oscillated in the cathedral of Pisa) and the laws of the accelerated movement, which he established after moving to teach at the University of Padua in 1592. In Padua, however, and then in Florence, Galileo deals primarily with astronomy and will do so intensely until 1633.

In 1609 he heard that in the Netherlands they had invented a new optical instrument, the telescope. In December 1609 Galileo had already built his own twenty-magnification telescope, with which he discovered mountains and craters on the Moon. He also noted that the Milky Way was composed of stars and discovered the four major satellites of Jupiter. In March 1610 he published these discoveries in The Messenger of the Stars.

His fame earned him being appointed mathematician of the court of Florence, where he was free of his academic responsibilities and was able to devote himself to research and writing. In December 1610 he could observe the phases of Venus, which contradicted the astronomy of Ptolemy and confirmed his acceptance of Copernicus theories.

In early 1616, the books of Copernicus were censored by an edict, and Jesuit Cardinal Roberto Belarmino instructed Galileo not to defend the theory that the Earth moved. Galileo remained silent on the subject for some years and devoted himself to investigating a method to determine latitude and longitude at sea based on his predictions about the positions of Jupiter satellites.

In 1624 Galileo began writing a book he wanted to headline Dialogue on the Tides, in which he addressed the hypotheses of Ptolemy and Copernicus regarding this phenomenon. In 1630 the book obtained the license of the censors of the Roman Catholic Church, but they changed the title to Dialogue on maximum systems, published in Florence in 1632.

Despite having obtained two official licenses, Galileo was called to Rome by the Inquisition in order to prosecute him on charges of "serious suspicion of heresy." Galileo was forced to abjure in 1633 and was sentenced to life imprisonment (sentence that was commuted to house arrest). The copies of the Dialogue were burned and the sentence was read publicly in all universities.

Galileo's latest work, Considerations and mathematical demonstrations on two new sciences related to mechanics, published in Leiden in 1638, reviews and refines his first studies on movement and the principles of mechanics in general. This book opened the way that led Newton to formulate the law of universal gravitation, which harmonized Kepler's laws on the planets with Galileo's mathematics and physics.

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