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Member Number: 4386
Galileo Galilei (15 February 1564 – 8 January 1642) was an Italian physicist, astronomer, astrologer, and philosopher who is closely associated with the scientific revolution. His achievements include the first systematic studies of uniformly accelerated motion, improvements to the telescope, a variety of astronomical observations, and support for Copernicanism. Galileo's experiment-based work is a significant break from the abstract approach of Aristotle. Galileo is often referred to as the "father of modern astronomy," as the "father of modern physics", and as the "father of science". The motion of uniformly accelerated objects, treated in nearly all high school and introductory college physics courses, was studied by Galileo as the subject of kinematics.
Galileo was born in Pisa, in the Tuscany region of Italy, on February 15, 1564, the first of six children of Vincenzo Galilei. Although as a young man he seriously considered the priesthood, at his father's urging he enrolled for a medical degree at the University of Pisa. He did not complete this degree, but instead studied mathematics, in 1589 being appointed to the chair of mathematics in Pisa. In 1592 he moved to the University of Padua, teaching geometry, mechanics, and astronomy until 1610. During this period Galileo made significant discoveries in both pure science (e.g., kinematics of motion, and astronomy) and applied science (e.g., strength of materials, improvement of the telescope).
Although a devout Roman Catholic, Galileo fathered three children out of wedlock with Marina Gamba. They had two daughters (Virginia in 1600 and Livia in 1601) and one son (Vincenzio, in 1606). Because of their illegitimate birth, both girls were sent to the convent of San Matteo in Arcetri at early ages and remained there for the rest of their lives. Virginia (b. 1600) took the name Maria Celeste upon entering the convent. Galileo's eldest child, she was also the most beloved, and inherited her father's sharp mind. She died on April 2, 1634, and is buried with Galileo at the Basilica di Santa Croce di Firenze. Livia (b. 1601) took the name Suor Arcangela and was ill for most of her life. Vincenzio (b. 1606) was later legitimized and married Sestilia Bocchineri.
In 1610, Galileo published an account of his telescopic observations of the moons of Jupiter, using this observation to argue in favor of the sun-centered, Copernican theory of the universe against the dominant earth-centered Ptolemaic and Aristotelian theories. The next year Galileo visited Rome in order to demonstrate his telescope to the influential philosophers and mathematicians of the Jesuit Collegio Romano, and to let them see with their own eyes the reality of the four moons of Jupiter. While in Rome he was also made a member of the Accademia dei Lincei. In 1612, opposition arose to the Sun-centered solar system which Galileo supported. In 1614, from the pulpit of Santa Maria Novella, Father Tommaso Caccini (1574-1648) denounced Galileo's opinions on the motion of the Earth, judging them dangerous and close to heresy. Galileo went to Rome to defend himself against these accusations, but, in 1616, Cardinal Roberto Bellarmino personally handed Galileo an admonition enjoining him neither to advocate nor teach Copernican astronomy.[1] In 1622, Galileo wrote his first book, The Assayer (Saggiatore), which was approved and published in 1623. In 1624, he developed the first known example of the microscope. In 1630, he returned to Rome to apply for a license to print the Dialogue Concerning the Two Chief World Systems, published in Florence in 1632. In October of that year, however, he was ordered to appear before the Holy Office in Rome.
Astronomy
Contributions
Based only on sketchy descriptions of the telescope, invented in the Netherlands in 1608, during that same year Galileo made one with about 3x magnification, and later made others with up to about 32x magnification. With this improved device he could see magnified, upright images on the earth - it was what is now known as a terrestrial telescope, or spyglass. He could also could use it to observe the sky; for a time he was one of very few who could construct telescopes good enough for that purpose. On August 25, 1609, he demonstrated his first telescope to Venetian lawmakers. His work on the device made for a profitable sideline with merchants who found it useful for their shipping businesses. He published his initial telescopic astronomical observations in March 1610 in a short treatise entitled Sidereus Nuncius (Starry Messenger).
It was on this page that Galileo first noted an observation of the moons of Jupiter. This observation upset the notion that all celestial bodies must revolve around the Earth. Galileo published a full description in Sidereus Nuncius in March 1610.
It was on this page that Galileo first noted an observation of the moons of Jupiter. This observation upset the notion that all celestial bodies must revolve around the Earth. Galileo published a full description in Sidereus Nuncius in March 1610.
In the week of January 7, 1610 Galileo discovered three of Jupiter's four largest satellites (moons): Io, Europa, and Callisto. He discovered Ganymede four nights later. He noted that the moons would appear and disappear periodically, an observation which he attributed to their movement behind Jupiter, and concluded that they were orbiting the planet. He made additional observations of them in 1620. Later astronomers overruled Galileo's naming of these objects, changing his originally named Medicean stars (after his patrons, the Medici) to Galilean satellites. 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.
From September 1610 Galileo observed that Venus exhibited a full set of phases similar to that of the Moon. The heliocentric model of the solar system developed by Copernicus predicted that all phases would be visible since the orbit of Venus around the Sun would cause its illuminated hemisphere to face the Earth when it was on the opposite side of the Sun and to face away from the Earth when it was on the Earth-side of the Sun. In contrast, the geocentric model of Ptolemy predicted that only crescent and new phases would be seen, since Venus was thought to remain between the Sun and Earth during its orbit around the Earth. Galileo's observations of the phases of Venus proved that it orbited the Sun and lent support to (but did not prove) the heliocentric model.
Galileo was one of the first Europeans to observe sunspots. He also reinterpreted a sunspot observation from the time of Charlemagne, which formerly had been attributed (impossibly) to a transit of Mercury. The very existence of sunspots showed another difficulty with the unchanging perfection of the heavens as assumed in the older philosophy. And the annual variations in their motions, first noticed by Francesco Sizi, presented great difficulties for both the geocentric system and that of Tycho Brahe. A dispute over priority in the discovery of sunspots, and in their interpretation, led Galileo to a long and bitter feud with the Jesuit Christoph Scheiner; in fact, there is little doubt that both of them were beaten by David Fabricius and his son Johannes. Scheiner quickly adopted Kepler's 1615 proposal of the modern telescope design, which gave larger magnification at the cost of inverted images; Galileo apparently never changed to Kepler's design.
Galileo was also 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 observed the Milky Way, previously believed to be nebulous, and found it to be a multitude of stars packed so densely that they appeared to be clouds from Earth. He located many other stars too distant to be visible with the naked eye. Galileo also observed the planet Neptune in 1612, but did not realize that it was a planet and took no particular notice of it. It appears in his notebooks as one of many unremarkable dim stars.
Galileo made at least one major scientific error, in addition to opposing Kepler's hypothesis that the gravity of the moon is the origin of the tides. This was his view on the origin of the comets of 1618. He argued vehemently in The Assayer that they were an optical illusion, in opposition to the interpretation of the Jesuit Orazio Grassi that they were real, and quite distant from the Moon. His alienation of both Scheiner and Grazzi likely contributed to the hostile response of the Jesuit order to his publication of "Dialogue Concerning the Two Chief World Systems" in 1632, and the inquisition that followed.
Galileo, Kepler, and theories of tides
Cardinal Bellarmine had written in 1615 that the Copernican system could not be defended without "a true [physical] demonstration that the sun does not circle the earth but the earth circles the sun" (Finocchiaro 1989:67-9). Galileo considered his theory of the tides to provide the required physical proof of the motion of the earth. This theory was so important to Galileo that he originally intended to entitle his Dialogue on the Two Chief World Systems the Dialogue on the Ebb and Flow of the Sea (Finocchiaro 1989:p. 354, n. 52). For Galileo, the tides were caused by the sloshing back and forth of water in the seas as a point on the Earth's surface speeded up and slowed down because of the Earth's rotation on its axis and revolution around the Sun. Galileo circulated his first account of the tides in 1616, addressed to Cardinal Orsini (Finocchiaro 1989:119-133).
If this theory were correct, there would be only one high tide per day. Galileo and his contemporaries were aware of this inadequacy because there are two daily high tides at Venice instead of one, about twelve hours apart. Galileo dismissed this anomaly as the result of several secondary causes, including the shape of the sea, its depth, and other factors (Finocchiaro 1989:127-131; Drake 1953:432-6). Against the assertion that Galileo was deceptive in making these arguments, Albert Einstein expressed the opinion that Galileo developed his "fascinating arguments" and accepted them uncritically out of a desire for physical proof of the motion of the Earth (Einstein 1952:xvii).
Galileo dismissed as a "useless fiction" the idea, held by his contemporary Johannes Kepler, that the moon caused the tides (Finocchiaro 1989:128). Galileo also refused to accept Kepler's elliptical orbits of the planets,[3] considering the circle the "perfect" shape for planetary orbits.
- Original documents on the trial of Galileo Galilei in the Vatican Secret Archives
- Biography of Galileo Galilei and objects from the Museum of the History of Science in Florence.
- Galileo theme-based virtual museuem visit including videos
- Galileo's "Notes on Motion" - online digital edition.
- Galileo's compass an educational interactive application.
- Galileo//Thek@ - archive of Galilean resources - bibliographies, biographies, digital books, itineraries, manuscripts, experiments, documents, iconography, and more
- Galileo Affair catholic.net
- The Galileo Affair by Paula Newall.
- The Warfare of Science With Theology
- The Galileo Project at Rice University
- CCD Images through a Galilean Telescope Modern recreation of what Galileo might have seen;.
- about Galileo Galilei at danask.com
- Electronic representation of Galilei's notes on motion (MS. 72)
- From Myth to History and Back -- Reviews of books on Galileo
- PBS Nova Online: Galileo's Battle for the Heavens
- Stanford Encyclopedia of Philosophy entry on Galileo -- This work is highly recommended.
- The Galilean Library, educational site.
- Galileo's writings in Italian, free e-texts
- Galileo Galilei - Catholic Encyclopedia entry an orthodox Catholic account
- Galileo and the Catholic Church article at Catholic League
- Galileo's Astrology
- O'Connor, John J., and Edmund F. Robertson. "Galileo Galilei". MacTutor History of Mathematics archive.
- LIFE top 100 events of the millennium: Galileo Galilei (nr 5 in this list)
- Galileo Galilei on a banknote.
- (Italian) La Bilancetta (MetaLibri Digital Library)
- Works by Galileo Galilei: text with concordances and frequencies.
- Short biography of Galileo concentrating on his achievements.
IMDB
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How the Telescope Changed Our Minds by Extending Our Eyes Wired News - News of Hans Lippershey's 1608 patent reached Galileo Galilei the following year. Within one day, he had made his own telescope, and, in 1610, ... The Telescope: 400 Years and Counting The Design of Extremely Large Telescopes |
Galileo Galilei turns in his grave Times Online, UK - The rejection of the organismic view of Greek “science” is often associated with Galileo, who discovered the law of inertia that is at the heart of ... |
Telescope demonstration wraps up celebration of astronomy milestone The Roundup, CA - The year 2009 is the International Year of Astronomy (IYA), a celebration of Galileo Galilei's world-changing discoveries since he first looked up into the ... |
Intriguing Jupiter is always worth a look Newsday, NY - It was nearly four centuries ago that the great Italian astronomer Galileo Galilei first aimed his telescope toward the heavens. Over time his new optical ... |
Today In History Daily Times, Pakistan - 1633 Galileo Galilei is tried before the Inquisition for teaching that the Earth orbits the Sun. 1857 The Indian Mutiny ends with the recapture of Delhi by ... |
 BBC News | Galileo satellite knocked offline BBC News, UK - Galileo's improved clocks are expected to deepen and extend this role. The better penetration and guarantees of service promised by Galileo should also give ... |
AS NIGERIA CLOCKS FORTY EIGHT Nigerian Muse, DC - Like Galileo Galilei, almost branded a heretic and personally handed, by Cardinal Roberto Bellarmino, an admonition warning him off teaching or even ... |
 anna.aero - Airline network news & analysis | Pisa topping Italian airport growth rankings; Ryanair now serves ... anna.aero - Airline network news & analysis, UK - In both 2006 and 2007 Pisa Galileo Galilei International Airport (PSA) was the fastest growing among Italy’s top 15 airports with passenger numbers up ... |
Galileo stars, but horse industry feels the pinch Irish Times, Ireland - Galileo's sire has now been retired from his role as the most important stallion to stand in Europe, and O'Byrne reported: "There are only so many Sadler's ... |
This Week in Physics History: September 15 - 21 About - News & Issues, NY - 20, 1633 - Galileo Galilei is tried before the inquisition of the Catholic Church on charges of heresy for teaching that the Earth orbits around the sun. ... |
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