Universe 1

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The Copernican Revolution

The Sun-Centered Universe

To me, whether the Earth revolves around the Sun, or the otherway around, no question could have any less importance.

- Albert Camus

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Copernicus

What's in the Center?

Two Questions1) Does the Earth rotate or the Celestial

Sphere?2) Does the Earth go around the Sun or the

Sun around the Earth?

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Copernicus

Aristotle

The Celestial Sphererotates.

The Sun movesaround the Earth.

The Earth iscompletely stationary.

Aristotle

Universe 2

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Copernicus

Aristarchos According to Archimedes, taught:1) The Earth rotates on its axis.2) The Earth moves around the Sun.

Archimedes

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Copernicus

The Stellar Parallax

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Ptolemy

The Great Astronomer - 150 AD the Almagest—astronomy textbook Found no stellar parallax. Argued against Aristarchos. Developed theory of motion of the

planets.

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Copernicus

Stellar Parallax

Q. The failure to observe the stellarparallax proved that…

1) The Sun went around the Earth.

2) The Earth went around the Sun.

3) Somebody needed to get busyand invent the telescope.

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Copernicus

The Problem ofPlanetary Motion

1) Why do the inferior planets never reachopposition?

2) Why do the superior planets go backward(retrograde) at opposition?

Retrograde motion of Mars

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Copernicus

The Ptolemaic Theory The Earth is the center. The Sun and all the

planets orbit the Earth. The planets move in

epicycles.

Earth

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Copernicus

Unanswered Questions

Why do the superior planets go intoretrograde only at opposition?

Why do the inferior planets go intoretrograde only at inferior conjunction?

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The Dark Ages

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Copernicus

Astronomy in 1500 Earth-centered model

unquestioned. Alphonsine Tables (1252) used to

calculate planet motions. Planets often far from predicted

positions.

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Copernicus

Nicolaus Copernicus

Born Torun, Poland 1473. Educated Cracow and Italy Canon at Cathedral of

Frauenburg, Ermland, Prussia Published On the Revolution

of the Spheres in 1543 Died 1543.

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Copernicus

The Sun-centered System

Sun

Q. What isnot goingaround theSun?

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Copernicus

Europe in 1500

Aristotle was considered the authority in philosophy. Experimentation was unrespectable. Astronomy was the only respectable natural science. Earth-centered Universe was tied to Christian

theology. Earth the place of suffering;

heaven the place of perfection.

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Copernicus

Winds of change

1450 – printing press 1492 - Columbus 1520 – Martin Luther 1543 – Copernicus publishes the

Sun-centered theory

Martin Luther

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Copernicus

Arguments for theCopernican Theory Puts the largest body (Sun) in the

center. Treats all the planets alike. Explains Venus & Mercury simply. Explains retrograde motion of

Mars, Jupiter, and Saturn simply. Predicted relative distances of the

planets from Sun.

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Copernicus

Occam’s Razor

When choosing between two competing theories,choose the simpler one.

"Entia non sunt multiplicanda sine necessitate".- William of Occam

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Arguments Against theCopernican Theory

It contradicted Scripture(?) Lack of effects of Earth’s rotation. Earth would fall to center due to

gravity. Failure to observe the stellar

parallax.

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Copernicus

The Controversy Begins

Reinhold: Prutenic Tables(1551)

Thomas Digges (1576) William Gilbert (1600) Giordano Bruno (1600)

Bruno

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Copernicus

The Execution of Bruno