The Copernican Revolution

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The Copernican Revolution
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Ptolemaic model was not seriously challenged
until the 15th century during the Renaissance.
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Nicholas Copernicus (1473-1543) rediscovered the
heliocentric model (Aristarchus).
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He found to his dismay that it better fit the
observed facts than the geocentric model.
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Seven points of the Copernican system
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1. The celestial spheres do not have one common
center. The Earth is not at the center of
everything.
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2. Earth is not the center of the universe, only
the center of gravity and the lunar orbit. Only
the Moon orbits Earth.
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3. All the spheres orbit the Sun. Spheres means
the planets.
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4. Compared to the distance to the stars, the
Earth to Sun distance is almost nonexistent. The
stars are very much farther away than the Sun.
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5. The motion of the stars is due to the Earth
rotating on its axis.
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6. The motion of the Sun is the result of the
Earths motions. (rotation and revolution)
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7. The retrograde and forward motions of planets
is caused by the Earths motion. It is caused
by the fact that Earths orbit is a different
length than the other planets.
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The Copernican model was not well accepted by
scholars or the public. It violated the religious
teaching of the time.
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Copernicus book De Revolutionibus was
published in 1543 (the year Copernicus died).
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It included an anonymous preface that stated that
the new model was merely an aid to calculation
and suggested that Copernicus really did not
believe it.
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Galileo Galilei (1564-1642) Italian
mathematician and philosopher. He performed
experiments to test his ideas (a radical idea
then). He is regarded as the father of
experimental science.
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The telescope was invented in Holland early in
the 17th century. Galileo heard about it and,
although never having seen one, made his own in
1609.
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With it he saw the mountains, valleys, and
craters of the Moon spots on the Sun (which
eventually blinded Galileo) the phases of Venus
and, perhaps most significant
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he saw 4 moons orbiting Jupiter (known as the
Galilean moons).
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All these observations suggested that the
Ptolemaic model was wrong and the Copernican
model was correct.
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Galileo published his findings in Siderius
Nuncius (The Starry Messenger) in 1610.
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This was a very risky action for Galileo. In
1600 Giordano Bruno was burned at the stake in
Rome for (among other things) teaching that the
Earth orbited the Sun.
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In 1616, Copernicus works were banned by the
Roman Church and Galileo was told to stop
researching and stating such nonsense.
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Galileo published a new book in 1632 Dialogue
Concerning the Two Chief World Systems.
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Three people debating the Ptolemaic and
Copernican models. The Aristotelian wins, but
his arguments are obviously inferior. His name?
Simplicio.
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Also, this book was written in Italian, not
Latin, so the common man could read this book.
The church was not amused.
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The Inquisition forced Galileo, under threat of
torture, to recant his claim that the Earth
orbited the Sun.
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He was placed under house arrest in 1633 and
remained imprisoned until his death in 1642.
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Galileos crimes were publicly forgiven by the
Catholic Church in 1992.
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But, by this time the damage was done, and the
Copernican model continued to gain acceptance as
the years passed.
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Earths orbit of the Sun couldnt be proven until
the unmanned probes of the 1960s, 70s, and
80s.
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The fact that the Earth moves at all was proven
by parallax in the 19th century.
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From Aristarchus belief until actual proof took
over 2000 years.
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Copernican principle - Earth is not special in
a cosmological sense.
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