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[[Image:galileo.gif|thumb|300px|Galileo Gallilei]]

[[Image:galileo.gif|thumb|300px|Galileo Gallilei]]

1564-1642  Italian physicist and astronomer who improved the [[telescope]] and was prosecuted for publishing certain heliocentric ideas.

1564-1642  Italian physicist and astronomer who improved the [[telescope]] and had a famous dispute with the Catholic Church.

Until the sixteenth century, people believed the [[Sun]], [[Moon]], [[star]]s and [[planet]]s circled the [[Earth]]. Puzzled astronomers noticed that [[Mars]], [[Jupiter]] and [[Saturn]] sometimes seemed to move backwards. A Polish astronomer, Nicolaus [[Copernicus]] (1473-1543), said that if the earth and other planets circled the sun, spinning as they went, this explained what they saw.  Few people believed him,  because his ideas contradicted the teachings of the [[Bible]] and ancient [[Greek philosophers]].

Until the sixteenth century, the prevailing view was that the [[Sun]], [[Moon]], [[star]]s and [[planet]]s circled the [[Earth]]. Puzzled astronomers noticed that [[Mars]], [[Jupiter]] and [[Saturn]] sometimes seemed to move backwards, but their motions were well predicted by Ptolemy's theory. A Polish astronomer, Nicolaus [[Copernicus]] (1473-1543), published a model of the solar system in which the earth and other planets circled the sun, with Catholic Church approval.  The scientific evidence was inconclusive.

Galileo tested [[Aristotle]]'s theory that heavy objects fall faster than light ones and found it to be in error. By making careful measurements he found he could use mathematics to predict how things fell and the movements of pendulums and tides. This was a new way of testing theories, but Galileo’s theories only worked if he assumed that [[Copernicus]] was right.

Galileo tested [[Aristotle]]'s theory that heavy objects fall faster than light ones and found it was a consequence of air resistance, not gravity. By making careful measurements he found he could use mathematics to predict how things fell and the movements of pendulums and tides. His theory of tides turned out to be mistaken.

In June or July of 1609, word reached Galileo the telescope, which had been invented in Holland.  Without knowing the technical details of the construction of the device, he managed to create one for himself.  With it, he was able to witness a supernova, observe our moon, and document the phases of Venus. He also located sunspots. These discoveries helped support a [[heliocentric]] system.

In June or July of 1609, word reached Galileo the telescope, which had been invented in Holland.  Without knowing the technical details of the construction of the device, he managed to create one for himself.  With it, he was able to witness a supernova, observe our Moon, and document the phases of Venus. He also located sunspots. Some of these discoveries helped support a [[heliocentric]] system.

Because the idea that the earth moves contradicted religious teachings, the [[Catholic Church]] decided against Galileo in 1616 and said that 1) the immobility of the Sun at the center of the universe was absurd in philosophy and formally heretical, and that 2) the mobility of Earth was absurd in philosophy and at least erroneous in theology. <ref> http://www.hps.cam.ac.uk/starry/galileo.html </ref> In 1632 Galileo published a book about tides, and against the Church's instructions discussed in it whether the earth or the sun was the center of the universe. Church authorities arrested him, forced him to say he was mistaken, and burned his book. Galileo went back to studying motion and mechanics.  

Because Galileo overstated the scientific case for the heliocentric theory, the [[Catholic Church]] decided against Galileo in 1616 and said that 1) the immobility of the Sun at the center of the universe was absurd in philosophy and formally heretical, and that 2) the mobility of Earth was absurd in philosophy and at least erroneous in theology. <ref> http://www.hps.cam.ac.uk/starry/galileo.html </ref> In 1632 Galileo published a book about tides, and against the Church's instructions he advocated the heliocentric theory. He also ridiculed the Pope. Church authorities arrested him, and forced him to say he was mistaken. Galileo went back to studying motion and mechanics.  

Galileo's work was one of the first examples of the use of the [[scientific method]], involving testing a theory by experiment and observation.

Galileo's work is often cited as an early example of the use of the [[scientific method]], involving testing a theory by experiment and observation.

In 1741, many years after Galileo's death, the Church under Pope Benedict XIV bid the Holy Office grant an imprimatur to the first edition of the <i>Complete Works of Galileo</i>.<ref>  [http://www.catholiceducation.org/articles/history/world/wh0005.html  The Galileo Affair ]</ref>

In 1741, many years after Galileo's death, the Church under Pope Benedict XIV bid the Holy Office grant an imprimatur to the first edition of the <i>Complete Works of Galileo</i>.<ref>  [http://www.catholiceducation.org/articles/history/world/wh0005.html  The Galileo Affair ]</ref>

Stillman Drake of the University of Toronto [http://www.utpjournals.com/product/utq/701/galileo46.html] was for the last decades of his life the most original and important scholar to study this seventeenth-century physicist.<ref>[http://www.chass.utoronto.ca/imago/drake.html|The Stillman Drake Collection]</ref>

Stillman Drake of the University of Toronto [http://www.utpjournals.com/product/utq/701/galileo46.html] was for the last decades of his life the most original and important scholar to study this seventeenth-century physicist.<ref>[http://www.chass.utoronto.ca/imago/drake.html|The Stillman Drake Collection]</ref> == References == <references /> [[category:physicists]]

== References ==

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[[category:physicists]]