copernican theory

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February 15th 1564: Galileo Galilei born

On this day in 1564, Italian astronomer Galileo Galilei was born near Pisa. As a young man, Galileo began studying medicine at the University of Pisa, but later changed to philosophy and mathematics. He left university before graduation due to financial difficulties, but went on to have a successful academic career. Galileo became interested in astronomy around the time of the invention of the telescope, and soon developed his own. He proved a talented astronomer, discovering mountains and valleys on the moon, four of Jupiter’s moons, and the phases of Venus. Galileo’s success did not go unnoticed, and he was appointed court mathematician in Florence. However, Galileo was accused of heresy for supporting the Copernican theory that the sun, not the Earth, was at the centre of the solar system. The Church turned against Galileo, and in 1632 he was summoned to the Inquisition in Rome. After a long trial, and with the threat of torture hanging over him, Galileo recanted his support for Copernican theory. The Inquisition found him guilty and sentenced him to life imprisonment, which was commuted to permanent house arrest. Galileo continued to research and write until his death in January 1642 aged 77. The Church officially dropped its opposition to heliocentrism in 1835, and Galileo has since been redeemed and acknowledged as the great scientific mind he was.

A Heliocentric Cosmos

Nicolaus Copernicus. De Revolutionibus Orbium Coelestium, Libri VI. Nuremberg: Ioh. Petreius, 1543.

This volume is the first edition of the work that set forth evidence that the earth and other planets revolve around the sun. Written by Polish astronomer, Nicolaus Copernicus (1473-1543), and published just before his death, the work was met by tremendous opposition because it contradicted religious beliefs of the time. The Copernican views provided the basis for the later work of Johannes Kepler (1571-1630), Galileo (1564-1642), and Isaac Newton (1642-1727).