The Trial of Galileo: A Chronology
1514 Nicolaus Copernicus (or Kopernig) produces the first feasible model of a sun-centered system.
Feb. 15, 1564 Galileo Galilei is born in Pisa, Italy.  (Also in 1564, Shakespeare is born and Michelangelo dies.)
1582 Tycho Brahe offers a compromise between the Aristotelian and Copernican models.  Brahe's model has the sun and moon orbiting a stationary earth, but shows the other planets orbiting the sun.
1574 The Galilei family moves from Pisa to Florence.
1597 Galileo tells friends that he thinks the Copernican model of the universe makes sense.  He writes to Kepler in Prague, "Like you, I accepted the Copernican position several years ago and discovered from thence the causes of many natural effects which are doubtless inexplicable by the current theories."
1600 Dissident thinker Giordano Bruno is convicted of heresy by the Holy Office and burned at the stake.
1609 Galileo learns of a "spy glass" made by a Dutch eyeglass maker that magnifies distant objects.  Galileo constructs several models of the device and displays an 8X telescope at the Venetian Senate.  Johannes Kepler publishes his first two laws of planetary motion.
1610 Galileo builds a 30X telescope.  He uses the telescope to make several important astronomical discoveries, including four moons of Jupiter, the ring of Saturn, the phases of Venus, and craters and mountains of the moon.  His observations of moons revolving around Jupiter confirm for him the correctness of the Copernican model. Galileo also concludes from the irregular features of the moon that the moon is composed of matter similar to that of earth.
1611 Galileo observes sunspots.
April 1611 Cardinal Bellarmine aske Jesuit mathematicians to confirm Galileo's astronomical discoveries.  They do so, but offer interpretations for what they see that differ from Galileo's.
May 1611 Galileo travels to Rome where he is honored for his astronomical discoveries at a banquet by the mathematicians at Collegio Romano.
1612 Galileo publishes his Letters on Sunspots, offering his theory that the sun revolves on an axis.
November 1613 Father Lorini of Florence, a professor of ecclesiastical history, launches the first attack from the clergy on the Copernican theory.
December 1613 Galileo writes a letter to Benedetto Castelli, a professor of mathematics at the University of Pisa, offering his ideas concerning the relationship of science and Scripture.
February 1615 Dominican friar Niccolo Lorini files a complaint with the Roman Inquisition against Galileo's Copernican views.  Included with the complaint is a copy of Galileo's 1613 letter to Castelli.
April 1615 Cardinal Bellarmine cautions scientists to treat Copernican views as as hypothesis, not fact.
December 1615 Galileo travels to Rome to defend his Copernican views.
January 1616 Galileo argues in writing that tidal motion proves the the earth revolves.
February 1616 A committee of advisors to the Inquisition declares that holding the view that the Sun is the center of the universe or the earth moves is absurd and formally heretical.
February 26, 1616 Cardinal Bellarmine warns Galileo not to hold, teach, or defend Copernican theory.  According to an unsigned transcript found in the Inquisition file in 1633, Galileo is also enjoined from discussing his theory, either orally or in writing.
March 1616 The Congregation of the Index bans Copernicus' On the Revolutions until corrections can be added.  Galileo meets with Pope Paul V.
1619 After three comets appear in 1618 and prompt widespread speculation as to their nature, Galileo writes Discourse on Comets, which disputes Jesuit views on the subject.
1621 Galileo is elected Consul of the Academia Fiorentina.  Pope Paul V dies and is succeed by Gregory XV.
1623 Pope Gregory XV dies.  Cardinal Baberini is named Pope Urban VIII. Galileo publishes The Assayer, which offers his explanation for sunspots and comets.
1624 Galileo goes to Rome.  He has six audiences with the Pope and meets with influential cardinals.  Pope Urban VIII tells Galileo that he can discuss Copernican theory--so long as he treats it as an hypothesis.
April 1630 Galileo completes work on his Dialogue Concerning the Two Chief World Systems.
June 1630 Galileo obtains conditional approval from the Secretary of the Vatican for publication of Dialogue Concerning the Two Chief World Systems.
February 1632 Dialogue Concerning the Two Chief World Systems is printed.
Summer 1632 Distribution of Dialogue Concerning the Two Chief World Systems is stopped by Pope Urban VIII.  The Pope authorizes a special commission to examine the book.
September 1632 Based on the special commission's report, the Pope refers Galileo's case to the Roman Inquisition. 
October 1632 Galileo receives a summons to appear before the Inquisition.  Galileo asks that his trial be moved to Florence
November 1632 Galileo's request to have his trial transferred to Florence is refused.
December 1632 Three physicians declare that Galileo is too ill to travel to Rome.  The Inquistion rejects the physician's statement and declares that if Galileo does not travel to Rome voluntarily he will be arrested and taken in chains.
February 1633 Galileo arrives in Rome.  He is allowed to stay at the home of the Tuscan ambassador, but is forbidden to have social contacts.
April 1633 Galileo is interrogated before the Inquisition.  For over two weeks he is imprisoned in an apartment in the Inquisition building.  Galileo agrees to plead guilty to a lesser charge in exchange for a more lenient sentence.  He declares that the Copernican case was made too strongly in his book Dialogue Concerning the Two Chief World Systems, and offers to refute it in another book.
June 22, 1633 Galileo is sentenced to prison for an indefinite term.  Seven of ten cardinals presiding at his trial sign the sentencing order.  Galileo signs a formal recantation. Galileo is allowed to serve his term under house-arrest in the home of the archbishop of Siena.
December 1633 Galileo is allowed to return to his villa in Florence, where he lives under house-arrest.
April 1634 Galileo's daughter, Maria Celeste, dies.
January 1638 Galileo is now totally blind.  He petitions the Inquisition to be freed, but his petition is denied.
September 1640 John Milton visits Galileo.
1641 Galileo, in his last major contribution, proposes using pendulums in clocks.
January 8, 1641 Galileo dies in Arcetri.
1820 Papal Inquisition abolished..
September 11, 1822 College of Cardinals announces that "the printing and publication of works treating of the motion of the earth and the stability of the sun, in accordance with the opinion of modern astronomers, is permitted."  Two weeks later, Pope Pius VII ratifies the Cardinals' decree.
1835 Galileo's Dialogue Concerning the Two Chief World Systems is taken off the Vatican's list of banned books.
1992 Catholic Church formally admits that Galileo's views on the solar system are correct.
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