Galileo is born in Pisa.
He starts elementary school in Pisa.
He moves to Florence, where he is schooled by a private
He continues his studies with the Vallombrosan friars, probably commencing a novitiate.
He observes a comet for the first time.
His father removes him from school before he finishes his studies.
He enrolls at the University of Pisa.
He makes his first observations of the pendulum.
He begins his first studies of geometry under Ostilio Ricci.
He quits the University of Pisa and returns to Florence.
He writes, but does not publish, his Theorems concerning the Centre of Gravity of Solids .
He writes, but does not publish, The Little Balance.
He makes the acquaintance of the German Jesuit Christopher Clavius, professor of mathematics at the Roman College.
He holds two lessons at the Florentine Academy, entitled Circa il sito, la grandezza e la figura dell'Inferno di Dante.
He is appointed to the Chair in Mathematics at the University of Pisa.
He writes his Capitolo contro il portar la toga [Against wearing the Gown].
He travels throughout Tuscany and Liguria in the wake of his friend Giovambattista Ricasoli.
Galileo's first treatises on motion date from his period, under the title of De motu antiquiora.
Vincenzo Viviani reports that Galileo carries out numerous experiments on falling bodies from the Tower of Pisa.
He testifies at the trial over the inheritance of Giovambattista Ricasoli, whose will had been contested.
Vincenzo Galilei, Galileo's father, dies and is buried in the church of Santa Croce in Florence.
Galileo testifies at a second trial over the inheritance of Giovambattista Ricasoli.
He leaves Pisa to accept a Chair in Mathematics at the University of Padua.
He carries out a study for the Venetian Shipyards on the most effective positioning of oars on ships.
He writes, but does not publish, his Breve istruzione all'architettura militare.
The Venetian Senate grants him an invention patent for a machine for raising water.
He writes his Le mecaniche [Mechanics].
He constructs his geometrical and military compass.
He writes, for didactic purposes, his Trattato della sfera, ovvero cosmografia [Treatise on the Sphere, or Cosmography].
Two letters, to Mazzoni and Kepler, contain Galileo's first declarations in favor of the Copernican system.
Galileo hires Marcantonio Mazzoleni and sets up an instrument workshop in his home.
He participates in the founding of the Academy of the Ricoverati of Padua.
Tycho Brahe tries unsuccessfully to contact Galileo by letter.
Virginia, Galileo's and Marina Gamba's oldest daughter, is born.
Livia, Galileo's e Marina Gamba's second daughter, is born.
He formulates for the first time the isochronism principle of the pendulum.
He studies the properties of magnets and their iron "armor" in order to vary the position of their poles.
Vincenzo Gonzaga, Duke of Mantua, offers to engage Galileo as his Court mathematician, but he refuses.
Galileo is formally denounced as a heretic, together with Cesare Cremonini, to the Inquistional Tribunal of Padua, for being an astrologer and a non-practicing Catholic and for his involvement with a woman without religious recognition, but the accusation does not hold.
A supernova appears in the constellation of Ofiuco and Galileo uses it as the subject of three special lessons he holds at the University of Padua.
In a letter to Paolo Sarpi he expresses for the first time the proportion between space and time to the fourth power in spontaneous acceleration.
He collaborates on the composition of Girolamo Spinelli's Dialogo de Cecco di Ronchitti da Bruzene in perpuosito della stella nuova.
He starts teaching mathematics to Prince Cosimo de' Medici, the future Grand Duke of Tuscany.
He becomes a member of the Academy of Crusca.
He writes Le operazioni del compasso geometrico e militare.
Vincenzo, Galileo's and Marina Gamba's third child, is born.
Galileo denounces Baldassare Capra to the Administrators of the University of Padua for plagiarizing his treatise on the geometrical and military compass, and wins the suit.
He writes his Difesa contro alle calunnie et imposture di Baldesar Capra [Defence against the Calumnies and Impostures of Baldassare Capra].
The Grand Duke of Tuscany purchases a very powerful magnet from Giovanfrancesco Sagredo and Galileo brokers the deal.
He studies the motion of projectiles and in a letter to don Antonio de' Medici formulates for the first time the principle by which artillery shells shot at the same height, no matter how strong the thrust, will fall to the earth at the same velocity.
He constructs his first telescope and starts observing heavenly bodies.
He observes the moon's surface, which reveals itself to be rough and not smooth as was commonly believed.
He discovers four satellites orbiting Jupiter and names them the Medicean Starts in honor of the Medici House.
He publishes the The Starry Messenger.
He observes Saturn but cannot discern its ring and considers it a planet made up of three bodies.
He observes sunspots for the first time.
He is called to Florence as First Mathematician and Philosopher of the Grand Duke of Tuscany.
He takes his second trip to Rome to present his discoveries to the Roman College.
He joins the Lyncean Academy.
The Artistotelian Lodovico delle Colombe writes his book Contro il moto della terra [Against the Motion of the Earth], initiating publicly the position against Galileo's Copernicanism.
Galileo publishes his Discorso intorno alle cose che stanno in su l'acqua o che in quella si muovono [Discourse on Bodies on or in Water] against the positions of the Florentine Aristotelians.
He prints his History and Demonstrations concerning Sunspots and their Phenomena, arguing with the Jesuit Christoph Scheiner.
He writes, but does not publish, a Letter to Benedetto Castelli.
Virginia and Livia Galilei, Galileo's two daughters, enter the Convent of San Matteo at Arcetri.
Tommaso Caccini, during his sermon for the fourth Sunday of Advent, delivered in the church of Santa Maria Novella, launches a violent attack against Galileo and the Copernican theory.
Galileo writes, but does not publish, two letters to Monsignor Piero Dini defending the Copernican system.
He writes, but does not publish, a Letter to Cristina di Lorena.
Niccolò Lorini denounces Galileo in a letter to the Congregation of the Index, and Tommaso Caccini testifies against him before the Holy Office.
Galileo takes a third trip to Rome to defend himself from the accusations brought against him.
At the end of a trial the Copernican theory is censured and Galileo is admonished officially by Cardinal Bellarmino.
Galileo writes, but does not publish, his Discorso sul flusso e reflusso del mare [Discourse on Tides].
Galileo carries out experiments at the port in Leghorn using the celatone, a device for using the telescope at sea even in rough waters.
He retires to the villa of Bellosguardo.
Three comets appear at brief intervals to one another.
The Jesuit Orazio Grassi writes his De tribus cometis anni MDCXVIII disputatio astronomica [An Astronomical Disputation on the Three Comets of the year 1618].
Galileo, together with Mario Guiducci, responds with their Discorso sulle comete.
Orazio Grassi replies in turn with his Libra astronomica ac philosophica [The Astronomical and Philosophical Weighing Scales].
Galileo's mother, Giulia Ammannati, dies and is buried in Florence in the church of Santa Maria del Carmine.
In Paris Maffeo Barberini, the future Pope Urban VIII, publishes his Poemata, which also includes the Adulatio perniciosa [Pernicious adulation], a lyric poem praising Galileo's observations made with the telescope.
Galileo is elected Consul of the Florentine Academy, a position he will hold for two years.
Tommaso Campanella's Apologia pro Galileo [Defence of Galileo] is published in Frankfurt, though written years before, between 1615 and 1616, on the occasion of the trial against Galileo and the Copernican theory.
Maffeo Barberini becomes Pope Urban VIII.
Galileo prints The Assayer against Grassi's Libra.
Galileo takes his fourth trip to Rome, where he meets with Pope Urban VIII all of six times.
During a meeting in Rome, Galileo shows the parties present the enlargement of a fly with the aid of lenses. Subsequently he sends a replica of the instrument to Federico Cesi, calling it a «spyglass for seeing minute things close up».
In a letter to Francesco Ingoli, a jurist and Secretary of the Congregation of Propaganda Fide, Galileo defends the Copernican system and the idea of the Earth's motion, anticipating several arguments he will later develop in his Dialogo sopra i due massimi sistemi del mondo [Dialogue concerning the Two Chief World Systems].
In a letter to Federico Cesi, the Lyncean academician Johann Faber for the first time calls the «new spyglass for seeing minute objects» a microscope: «...the Lynceans, since they named the first object a telescope, have thought fit to apply this name, and deservedly so, being the first here in Rome to possess one».
Orazio Grassi publishes his Ratio ponderum librae et simbellae in which he contests Galileo's The Assayer even on a theological level.
Galileo is accused by the College of Inquisitors of «casting doubt upon» the Catholic dogma of the Eucharist, since in his Assayer he has supportd the atomist theory and thus denied the transformation of bread into wine and the body and blood of Christ. The accusation, after being discussed at the College of Inquisitors, is dismissed upon the decisive opinion of Cardinal Francesco Barberini, nephew of Pope Urban VIII.
Galileo is granted Florentine citizenship by Grand Duke Ferdinando II de' Medici.
Vincenzo Galilei, Galileo's son, marries Sestilia Bocchineri. On December 5th Galileo becomes a grandfather, since the two have a child whom they name Galileo.
The Galilei family purchase a house on Costa San Giorgio in Florence.
Galileo goes to Rome for the fifth time, where he once again meets Pope Urban VIII, who shows him great kindness.
Christoph Scheiner's Rosa Ursina [The Orsini Rose] is published, containing severe attacks against Galileo.
Federico Cesi, founder of the Lyncean Academy, dies in Rome.
Galileo pens a report entitled Scrittura sopra il fiume Bisenzio appraising two opposing proposals for altering the course of the river to prevent its frequent overflows.
Galileo sends the Grand Duke his opinion on the proposal made by the painter and architect Sigismondo Coccapani for reducing the Arno River to a canal. Galileo considers the details of the project to be insufficient for the purpose of making an evaluation, which he can do only after hearing its author in person.
The Dominican friar Niccolò Riccardi, Master of the Holy Palace, leaves it up to the Florentine Inquisitor Clemente Egidi to choose whether to grant permission to publish the Dialogo sopra i due massimi sistemi del mondo [Dialogue concerning the Two Chief World Systems]. Authorization is granted.
Galileo leases the villa 'Il Gioiello'in Pian de' Giullari and moves there.
Galileo publishes his Dialogo sopra i due massimi sistemi del mondo.
Galileo receives a summons from the Florentine Inquisitor to present himself in Rome for a hearing on the content of the Dialogo, but being in bad health he puts off the trip as long as possible.
Galileo goes to Rome for the sixth time, where he must undergo a trial, at the end of which he is forced to recant his scientific theories.
Galileo pronounces his recantation before the Tribunal of the Holy Office.
The Dialogo sopra i due massimi sistemi del mondo is placed on the Index.
Galileo gets permission to leave Rome and returns to Florence by way of Siena, where he resides at the Palace of Archbishop Ascanio Piccolomini and begins writing his Discorsi e dimostrazioni intorno a due nuove scienze [Discourses and Demonstrations concerning Two New Sciences].
Virginia Galilei, Galileo's favorite daughter, dies at the Convent of Arcetri.
Prince Mattias de' Medici departs for Germany with a copy of the first two days of the Discorsi e dimostrazioni matematiche intorno a due nuove scienze [Discourses and Demonstrations concerning Two New Sciences], intending to have it printed, without however succeeding in doing so.
Galileo proposes to the Staats General of the United Provinces of the Netherlands his method - already offered in the past to the Spanish government - for calculating longitude at sea by observing the moons of Jupiter.
He writes his Operazioni astronomiche, «a catalogue of the most important astronomical operations».
Galileo finally gets permission, often requested and till then denied, to move to his house in Costa San Giorgio to care for himself, given his increasingly precarious state of health. Shortly after he loses his eyesight completely.
In a letter to the nobleman Alfonso Antonini Galileo makes reference to the results of his studies on the phases of the moon.
In Leiden his Discorsi e dimostrazioni intorno a due nuove scienze [Discourses and Demonstrations concerning Two New Sciences] are printed.
Galileo takes in at his Arcetri villa the young Vincenzo Viviani on the recommendation of the Grand Duke Ferdinando II de' Medici.
He writes his Letter to Prince Leopold against Fortunio Liceti's Litheosphorus.
Galileo takes in at his Arcetri villa Evangelista Torricelli, whom he hosts up to his death.
In the appendix to his De lunae subobscura luce Fortunio Liceti publishes Galileo's letter on moonlight.
Galileo dies in his Arcetri Villa. Vincenzo Viviani, in his Racconto istorico della vita di Galileo Galilei [Historical Account of the Life of Galileo Galilei], thus describes his last moments: «Assailed by a persistent fever and by palpitations of the heart, after two months of an illness that little by little consumed his spirits, on Wednesday January 8, 1641 ab Incarnatione , at four in the morning, at the age of seventy-seven years, ten months and twenty days, with philosophical and Christian piety he gave up the ghost to his Creator, consoling himself in the belief that he would enjoy and marvel more amidst those eternal and immutable wonders than by means of a fragile artifice and with such avidity and impatience he had striven to draw close to the eyes of us mortals».
Galileo's body is deposed in the Basilica of Santa Croce, in a small room next to the Chapel of Saints Cosma and Damian. The project of a monumental sepulcher for someone condemned by the Church for «extreme suspicion of heresy» encounters the hostility of the ecclesiastical authorities, who dissuade the Grand Duke of Tuscany Ferdinando II de' Medici.
The Bolognese bookseller Carlo Manolessi publishes the first complete edition of Galileo's works (with the exception of the Dialogo sui massimi sistemi [Dialogue concerning the Two Chief World Systems], still included in the Index of banned books).
Leopoldo de' Medici and Grand Duke Ferdinando II sponsor the founding of the Academy of Cimento, whose task is to perpetuate Galileo's scientific legacy. The experimental method is presented as the logical extension of the example set by Galileo.
The publication of the Saggi di naturali esperienze, edited by the Secretary Lorenzo Magalotti, brings to a conclusion after ten years, and not without internal disagreements, the experimental activities of the Academy of Cimento.
Vincenzo Viviani has the Casa dei Cartelloni built and conceives the façade as a perennial homage to the memory of his maestro.
The Basilica of Santa Croce sees the inauguration of a monumental sepulcher in which Galileo's and Vincenzo Viviani's mortal remains are deposited.
Pope Benedict XIV lifts certain publications supporting the Copernican hypothesis of the earth's motion from the Index of banned books. Nevertheless, Copernicus' De revolutionibus orbium coelestium and Galileo's Dialogo sopra i due massimi sistemi del mondo [Dialogue concerning the Two Chief World Systems] remain on the Index of banned books.
Copernicus' (1473-1543) De revolutionibus orbium coelestium and Galileo's Dialogo sopra i due massimi sistemi del mondo [Dialogue concerning the Two Chief World Systems] are lifted from the Index of banned books.
At the Third Congress of Italian Scientists in Florence a monumental structure entitled "Galileo's Tribune" is inaugurated in the Museum of Physics and Natural History.
Antonio Favaro commences work on the national edition of the Opere di Galileo Galilei. The massive project, in 20 volumes and 21 tomes, is completed in 1909.
Antonio Favaro completes the national edition of the Opere di Galileo Galilei, begun nineteen years before.
The Science History Museum is founded in Florence. Conserved therein are Galileo's original prized instruments (including the only two surviving telescopes that Galileo made personally), some artifacts and numerous 18th and 19th century models illustrating Galileo's basic research of mechanics.
Pope John Paul II, in a speech at the Papal Science Academy celebrating the centennial of the birth of Albert Einstein, states that Galileo «suffered greatly - we cannot hide the fact - at the hands of men and institutions of the Church».
Pope John Paul II, in a speech given at the Papal Science Academy, states that the painful misunderstanding over the presumed conflict between science and faith is now a thing of the past. «Thus the new science, with its methods and the freedom of research they entail, obliged theologians to reassess the criteria of their interpretation of Holy Scripture. Most of them failed utterly to do so. Paradoxically, Galileo, sincere believer that he was, proved himself more insightful on this point than the theologians who were his opponents».
Texts by Sara Bonechi
English translation by Edward Tosques
Last update 22/feb/2008