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Copernicus
Picture of Copernicus
Copernicus, Nicolaus (1473-1543), Polish
astronomer, best known for his astronomical theory that the sun
is at rest near the center of the universe, and that the earth,
spinning on its axis once daily, revolves annually around the
sun. This is called the heliocentric, or sun-centered, system.
Copernicus was born on February 19,
1473, in Thorn (now Torun), Poland, to a family of merchants and
municipal officials. Copernicus's maternal uncle, Bishop Lukasz
Watzenrode, saw to it that his nephew obtained a solid education
at the best universities. Copernicus entered the University of
Kraków in 1491, studied the liberal arts for four years without
receiving a degree, and then, like many Poles of his social
class, went to Italy to study medicine and law. Before he left,
his uncle had him appointed a church administrator in Frauenberg
(now Frombork); this was a post with financial responsibilities
but no priestly duties. In January 1497 Copernicus began to study
canon law at the University of Bologna while living in the home
of a mathematics professor, Domenico Maria de Novara.
Copernicus's geographical and astronomical interests were greatly
stimulated by Domenico Maria, an early critic of the accuracy of
the Geography of the 2nd-century astronomer Ptolemy. Together,
the two men observed the occultation (the eclipse by the moon) of
the star Aldebaran on March 9, 1497.
In 1500 Copernicus lectured on astronomy
in Rome. The following year he gained permission to study
medicine at Padua, the university where Galileo taught nearly a
century later. It was not unusual at the time to study a subject
at one university and then to receive a degree from
another—often less expensive—institution. And so
Copernicus, without completing his medical studies, received a
doctorate in canon law from Ferrara in 1503 and then returned to
Poland to take up his administrative duties.
From 1503 to 1510, Copernicus lived in
his uncle's bishopric palace in Lidzbark Warminski, assisting in
the administration of the diocese and in the conflict against the
Teutonic Knights. There he published his first book, a Latin
translation of letters on morals by a 7th-century Byzantine
writer, Theophylactus of Simocatta. Sometime between 1507 and
1515, he completed a short astronomical treatise, De Hypothesibus
Motuum Coelestium a se Constitutis Commentariolus (known as the
Commentariolus), which was not published until the 19th century.
In this work he laid down the principles of his new heliocentric
astronomy.
After moving to Frauenburg in 1512,
Copernicus took part in the Fifth Lateran Council's commission on
calendar reform (1515); wrote a treatise on money (1517); and
began his major work, De Revolutionibus Orbium Coelestium (On the
Revolutions of the Celestial Spheres), which was finished by 1530
but first published by a Lutheran printer in Nuremberg, Germany,
just before Copernicus's death on May 24, 1543.
The cosmology that was eventually
replaced by Copernican theory postulated a geocentric universe in
which the earth was stationary and motionless at the center of
several concentric, rotating spheres. These spheres bore (in
order from the earth outward) the following celestial bodies: the
moon, Mercury, Venus, the sun, Mars, Jupiter, Saturn, and,
finally, the finite outermost sphere bearing the so-called fixed
stars. (This last sphere was said to wobble slowly, thereby
producing the precession of the equinoxes.)
One phenomenon had posed a particular
problem for cosmologists and natural philosophers since ancient
times: the apparent retrograde, or backward, motion of Mars,
Jupiter, and Saturn. From time to time the daily motion of these
planets through the sky appears to halt and then to proceed in
the opposite direction. In an attempt to account for this
retrograde motion, medieval cosmology stated that each planet
revolved on the edge of a circle called the epicycle, and the
center of each epicycle revolved around the earth on a path
called the deferent.
The major premises of Copernicus's
theory are that the earth rotates daily on its axis and revolves
yearly around the sun. He argued, furthermore, that the planets
also circle the sun, and that the earth precesses on its axis
(wobbles like a top) as it rotates. The Copernican theory
retained many features of the cosmology it replaced, including
the solid, planet-bearing spheres, and the finite outermost
sphere bearing the fixed stars. On the other hand, Copernicus's
heliocentric theories of planetary motion had the advantage of
accounting for the apparent daily and yearly motion of the sun
and stars, and it neatly explained the apparent retrograde motion
of Mars, Jupiter, and Saturn, and why Mercury and Venus never
move more than a certain distance from the sun. Copernicus's
theory also stated that the sphere of the fixed stars was
stationary.
Another important feature of Copernican theory is that it allowed
a new ordering of the planets according to their periods of
revolution. In Copernicus's universe, unlike Ptolemy's, the
greater the radius of a planet's orbit, the greater the time the
planet takes to make one circuit around the sun. But the price of
accepting the concept of a moving earth was too high for most
16th-century readers who understood Copernicus's claims. Instead,
parts of his theory were adopted, while the radical core was
ignored or rejected.
There were but ten
Copernicans between 1543 and 1600. Most worked outside the
universities in princely, royal, or imperial courts; the most
famous were Galileo and the German astronomer Johannes Kepler.
These men often differed in their reasons for supporting the
Copernican system. In 1588 an important middle position was
developed by the Danish astronomer Tycho Brahe in which the earth
remained at rest and all the planets revolved around the sun as
it revolved around the earth.
After the suppression of Copernican theory occasioned by the
ecclesiastical trial of Galileo in 1633, some Jesuit philosophers
remained secret followers of Copernicus. Many others adopted the
geocentric-heliocentric system of Brahe. By the late 17th century
and the rise of the system of celestial mechanics propounded by
the English natural philosopher Sir Isaac Newton, most major
thinkers in England, France, the Netherlands, and Denmark were
Copernicans. Natural philosophers in the other European
countries, however, held strong anti-Copernican views for at
least another century.
( Ptolemy - Copernicus - Kepler - Galileo - Newton )
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Copyright JoaoVicente.
Last update: 11/02/98.
