The Life of Galileo Galilei and His Contributions to Astronomy

The Life of Galileo Galilei and His Contributions to Astronomy

Early Life

Galileo Galilei was born in Pisa, Italy on February 15, 1564, the first of six children. His parents were Vincenzo Galilei, a music teacher and Giulia degli Ammannati. ("Galileo's Battle for the Heavens." PBS.) It could be said that even as a child, he was a genius. “From his earliest childhood Galileo was remarkable for intellectual aptitude as well as for mechanical invention.” ("Early Life of Galileo." 2020 Site) He’d construct original pieces of work, which others called “ingenious toy-machines” with no problem and was always interested in how they worked. By the age of fifteen, he had become very familiar with the Greek language, Latin and the study of logic, which he studied at the Benedictine monastery of Santa Maria di Vallombrosa. ("Galileo's Battle for the Heavens." PBS.) There, he considered becoming a monk until his father showed that he was not too fond of the idea. “In 1581, having had personal experience with both music and mathematics, he desired that his son should apply himself to the cultivation of medicine and placed him at the University of Pisa.” In 1585, though, he left the University of Pisa without a degree after four years of study and taught private lessons in mathematics in Florence and Siena. ("Early Life of Galileo." 2020 Site). Galileo became chair of the mathematics department at the University of Padua in the Republic of Venice ("Galileo Galilei 1564-1642." High Altitude Observatory). It wasn’t until 1595 that he developed his theory of the tides, asserting that they ebb and flow in relation to the Earth's diurnal and annual movements. His theory, though elegantly conceived, is incorrect.” ("Galileo's Battle for the Heavens." PBS.)

Improvements to the telescope

The telescope was invented by Dutchman Hans Lippershey, which he patented in 1608. Although it is believed that at around the same time, Roger Bacon and Leonard Digges assembled similar devices. The early telescope was called a spyglass and it is not known who first used it to look at the stars. (Levy 50). In Galileo’s first attempt at constructing a telescope, he took the lenses from spectacles and put them on each end of a tube. This enlarged objects by three times (Brewster Chapter 2). Galileo created an even more powerful telescope, which magnified objects by nine times. He also made drawings of the sky and stars (Levy 51).

In 1610, Galileo made a “30-power telescope,” and with it discovered four of Jupiter’s moons (Levy 51 and 53). He also created a moving eye piece at one end that enabled focusing of the device and attached the device to a firm base (Shea 22). He also studied sun spots through his telescope, which may have led to his blindness later in life (Levy 53).

He later improved the telescope by combining a concave lens with a convex lens. He got Senators interested in it, but they changed their minds after they realized he wasn’t the original inventor of the telescope (Shea 20).

There were many doubters of Galileo’s telescope device. Galileo released a booklet about the telescope called “Sidereus Nuncius.” Readers were either excited by the idea but still somewhat skeptical, or they thought it was a hoax (Shea, 26-28). Also, the early telescope was frustrating to some scientists because it was hard to focus and hard to keep the object in the field of vision (Shea, 40). Throughout the general public, Galileo’s telescope was extremely popular. It was manufactured in great quantities and was carried by many travelers (Brewster Chapter 2).

Observations of planets and stars

“When viewing bodies that are very bright and very small, the optical defects of the telescope can be crippling. By trial and error Galileo learned to stop down the aperture of his instrument until he could begin to make useful observations.” ("Satellites of Jupiter." The Galileo Project.) In September of 1610, Galileo left Padua and headed to Florence where his research with the telescope was rewarded. ("Galileo’s Observations and Inventions." 2020 Site) “The Sidereus Nuncius, published at Venice early in 1610, contained the first-fruits of the new mode of investigation, which were sufficient to excite learned amazement on both sides of the Alps. The mountainous configuration of the moon’s surface was first described as the dark portion of our satellite attributed to its true cause, namely, illumination by sunlight reflected from the earth.” ("Galileo’s Observations and Inventions." 2020 Site) At that point in time, the Milky Way was still seen to be nebulous rather than multitude of stars packed so densely that they appeared to be clouds from Earth.

Although the discovery of the Milky Way was a huge contribution made by Galileo, most people see his most important discovery to be Jupiter’s satellites, which he discovered on January 10, 1610 and named Sidera Medicea, in honor of the grand-duke of Tuscany, Cosmo II. ("Galileo’s Observations and Inventions." 2020 Site) Jupiter has a large number of moons; Io, Europa, Callisto and Ganymede. Of these, four are comparable to the Earth's Moon in size; the rest are orders of magnitude smaller...this means that, were it not for the shielding brightness of Jupiter, these bodies would be visible with the naked eye” ("Galileo Galilei." Nov. 2002. University of St Andrews, Scotland). Galileo noted that the moons would periodically appear and disappear and made the conclusion that they were orbiting the planet. “The demonstration that a planet had smaller planets orbiting it was problematic for the orderly, comprehensive picture of the geocentric model of the universe, in which everything circled around the Earth.”(Science Castle) These satellites became a problem for astronomers.

“Galileo was the first to report lunar mountains and craters, whose existence he deduced from the patterns of light and shadow on the Moon's surface. He even estimated the mountains' heights from these observations. This led him to the conclusion that the Moon was ‘rough and uneven, and just like the surface of the Earth itself,’ rather than a perfect sphere as Aristotle had claimed.” ("Galileo Galilei: Planets." Lycos). He also observed the sun and discovered that it had dark spots. (It has been said that this was the main cause of his blindness.) Continuing with his observations, he discovered that the sun rotated on an axis. The most important discovery though, would have to be that Venus went through a complete set of phases, just like the Moon. “This observation was among the most important in human history, for it provided the first conclusive observational proof that was consistent with the Copernican system but not the Ptolemaic system.” ("Galileo’s Observations and Inventions." 2020 Site)

“Galileo's belief in the Copernican System eventually got him into trouble with the Catholic Church. The Inquisition was a permanent institution in the Catholic Church charged with the eradication of heresies. A committee of consultants declared to the Inquisition that the Copernican proposition that the Sun is the center of the universe was a heresy. Because Galileo supported the Copernican system, he was warned by Cardinal Bellarmine, under order of Pope Paul V, that he should not discuss or defend Copernican theories. In 1624, Galileo was assured by Pope Urban VIII that he could write about Copernican theory as long as he treated it as a mathematical proposition. However, with the printing of Galileo's book, Dialogue Concerning the Two Chief World Systems, Galileo was called to Rome in 1633 to face the Inquisition again.” (The Galileo Project.)

The Copernican system is Copernicus' astronomical model in which the Earth rotates around the sun whereas the Ptolemaic system is known as the ancient geocentric cosmic schema, based in the belief that the planets, Sun, Moon and stars revolved around the earth). By discovering these amazing additions to the world of astronomy, Galileo has still proven himself to be a genius and an amazing historical figure in the eyes of many.

Later life

Galileo wrote a short book called “Starry Messenger,” which was published in 1610. In it, he described mountains on the moon. After that he became Chief Mathematician at The University of Pisa and Mathematician and Philosopher to the Grand Duke of Tuscany. In 1611, he was made a member of the Academia dei Lincei (History. mcs. st-andrews. ac. uk, 2009). He became so popular in his lectures at the university, that he eventually had to step down from lecturing to enable him to work on his studies and his writings (Brewster, Chapter 2).

Using his telescope in 1610, he discovered that Venus showed phases the same way that the moon does. He saw this as evidence that Venus orbited the sun and not earth, which was evidence of a Copernican system.

In 1614, his two daughters entered a convent outside of Florence. They were both born out of wedlock, so Galileo thought they should never marry (History. mcs. st-andrews. ac. uk, 2009). In 1616, Galileo wrote the “Letter to the Grand Duchess,” which he explained his belief in the ideas of Copernicus, that the planets, including earth, revolved around the sun. The Catholic Church, under Pope Paul V, declared that the views of Copernicus were incorrect and forbade anyone, including Galileo, from having those views (About. com, 2009). In 1623, Maffeo Barberini was elected Pope Urban VIII. He was an admirer of Galileo and was more forgiving of Galileo’s views. This was also the year that Galileo wrote “Il saggiatore” (“The Assayer”), in which Galileo described his scientific method. (History. mcs. st-andrews. ac. uk, 2009).

In 1624, he published his famous work “Dialogue Concerning the Two Chief Systems of the World – Ptolemaic and Copernican.” The Inquisition banned the sale of the book and ordered Galileo to appear before them in Rome, which he did in 1633. He was found guilty and sentenced to house arrest. He had to be observed by officers of the Inquisition for the rest of his life (History. mcs. st-andrews. ac. uk, 2009). The officials of the Inquisition claimed that Galileo had been, in 1616, ordered to not discuss Copernicanism (About. com, 2009).

Around this time, Galileo had been experiencing health problems. Sadly, his daughter Virginia died in 1634. Soon after, he wrote “Discourses and Mathematical Demonstrations Concerning the Two New Sciences,” which was an extremely focused mathematical piece. In it, he described his now famous findings of inclined planes and bodies in free fall. He also discovered the science of the pendulum and designed the first pendulum clock (History. mcs. st-andrews. ac. uk, 2009). It is thought that Galileo’s studies on motion led Isaac Newton to develop his law of universal gravitation (About. com, 2009).

Galileo died in 1642 after losing his eyesight. It wasn’t until 1992, that the Catholic Church formally admitted that their conviction of Galileo for his belief that the earth revolved around the sun was wrong (History. mcs. st-andrews. ac. uk, 2009).