who believed that the Sun, not the Earth, is at the centre of the Solar
System, thus defying the Christian church doctrine of the time. For
30 years he worked on the hypothesis that the rotation and the orbital
motion of the Earth were responsible for the apparent movement of the
heavenly bodies. His great work De revolutionibus orbium coelestium/On
the Revolutions of the Heavenly Spheres was not published until the
year of his death.
Copernicus relegated the Earth from being the centre of the universe
to being merely a planet (the centre only of its own gravity and the
orbit of its solitary Moon). This forced a fundamental revision of the
anthropocentric view of the universe and came as an enormous psychological
shock to European culture. Copernicus's model could not be proved right,
because it contained several fundamental flaws, but it was the important
first step to the more accurate picture built up by later astronomers.
Copernicus was born in Toru on the Vistula. He studied mathematics,
astronomy, classics, law, and medicine at Kraków and various
universities in Italy. On his return to Poland 1506 he became physician
to his uncle, the bishop of Varmia, who had also got him the post of
canon at Frombork, enabling him to intersperse astronomical work with
the duties of various civil offices.
Copernicus began to make astronomical observations in 1497, although
he relied mainly on data accumulated by others. In about 1513 he wrote
a brief, anonymous text entitled Commentariolus, in which he outlined
the material he later discussed in De revolutionibus.
Unable to free himself entirely from the constraints of classical thinking,
Copernicus was able to imagine only circular planetary orbits. This
forced him to retain the cumbersome system of epicycles, with the Earth
revolving around a centre which revolved around another centre which
in turn orbited the Sun. It was the work of Johannes Kepler, who introduced
the concept of elliptical orbits, that rescued the Copernican model.
Copernicus also held to the notion of spheres, in which the planets
were supposed to travel. It was Tycho Brahe who rid astronomy of that
A Lutheran minister oversaw the publication of De revolutionibus and
inserted a preface (without Copernicus's permission) stating that the
theory was intended merely as an aid to the calculation of planetary
positions, not as a statement of reality. This served to compromise
the value of the text in the eyes of many astronomers, but it also saved
the book from instant condemnation by the Roman Catholic Church. De
revolutionibus was not placed on the index of forbidden books until
1616 (it was removed from the list 1835).