1. The Solar System How do we know what we know to about
Part 1 -- Introduction (10 minutes )
Last week we studied the Laws of Motion. This week we will study an important application of those laws: the Solar System.
This is a subject that had great importance in the history of science, and indeed in the history of Western Civilization. The Middle Ages – that long period of ignorance and poverty – was ended by the Scientific Revolution; and the Scientific Revolution was driven by astronomy.
Today we’ll look at the properties of the Solar System, and how they were discovered. Then next time we’ll learn how Isaac Newton’s theories of motion and gravity explain the Solar System.
The Solar System
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2. Nicolaus Copernicus The Earth moves, in two ways.
It rotates on an axis (period = 1 day).
It revolves around the sun (period = 1 year).
Part 2 -- Copernicus (15 minutes)
The Copernican model was based on the hypothesis that the Earth moves, in two ways.
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3. The Copernican Model
The Scientific Revolution (1543 – 1687) was driven by astronomy. The famous names are
Copernicus… Galileo… Kepler… Newton…
After their advances in science, the human view of the universe had changed dramatically!
A question: At which position in our orbit around the sun are we today? A, B, C, or D?
Now… this picture was the beginning of a kind of conflict between science and religion. Galileo was tried for heresy in 1633, in the midst of the scientific revolution (next slide!) His crime was to argue in favor of the Copernican model.
Discovered that the Earth and other planets orbit the sun.
Take a moment to make sure this is on your chart!
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4. Galileo Galilei
Part 3 -- Galileo (15 minutes)

5. Galileo’s discoveries in Astronomy
Galileo did not invent the telescope, but when he heard about the invention he figured out how to build telescopes. He had the best telescopes of his time. He was the first person to use telescopes to look at the solar system. He was first, so he made the discoveries.
 Craters and mountains on the moon
 Moons of Jupiter
 Phases of Venus
 The Milky Way consists of innumerable stars.
 Sunspots move across the sun’s face.
Galileo was professor of mathematics, but also interested in the physical world. His believed that observations and experiments are the only way to know nature.
We have seen that his discoveries in physics came from observations and measurements. His discoveries in astronomy came from telescopes.
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6. Galileo’s sketch of the moon as seen from his telescope
A photograph of the moon
Here are a couple of pictures of the moon.
The first is Galileo’s sketch…{READ}
The second is a modern photograph…{READ}
So Galileo could see that the moon is not some ideal heavenly disk, but a real material sphere with craters and mountains. It was like another little world. However, as was often the case with Galileo, many philosophers did not want to accept his new knowledge. They just couldn’t bring themselves to admit that their whole world view was based on errors.
In a letter to Kepler, Galileo wrote… “{READ the quote}
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7. Accomplishments
Galileo made many specific discoveries in astronomy through observations by telescope, but his ideas about the universe were condemned by the Catholic Church.
Take a moment to make sure this information is on your chart!
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Galileo also asked what his discoveries would imply about the universe in general.
The general implications of his discoveries were significant evidence for the Copernican Model.
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8. The Trial of Galileo His Church decided that his model was a heresy.
But Galileo continued to argue in favor of the theory, and published his reasoning. The Inquisition in Rome accused him of heresy, and required him to answer.
Found guilty of “suspicion of heresy,” Galileo recanted publicly.
A dramatic event in the history of Europe was the Trial of Galileo, in the year 1633.
{READ up to “Found guilty”}
To comprehend this event, you must realize that Galileo was a good Catholic. He was educated in a monastery. His two daughters both became nuns. He wanted to obey the Church. He thought he had followed all their rules to get his book published; and the evidence of history is that he had indeed followed their rules. Nevertheless he was accused of heresy.
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For the final 8 years of his life, Galileo was not allowed to travel or meet people or speak about his discoveries in astronomy. During that period, even at such an advanced age, he continued to work on physics; physics was not so controversial as cosmology.
Did Galileo know that his ideas about cosmology would eventually be accepted, although not in his lifetime? [[etc]] Of course he knew.
He was put under arrest and sentenced to prison, but because of his fame and age (70 years old at that time) he was allowed to serve under house arrest in Florence, for the remaining years of his life.

9. Is there a conflict between Science and Religion?
What do you think?
Can you think of an example?
The trial of Galileo raises an interesting question.
Is there a conflict between Science and Religion?
Today most churches and sciences have come to terms with their differences. Science concerns the physical world; religion concerns the spiritual world. They are not in any real disagreement because they are concerned with different issues.
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Maybe you’ve seen the play “Inherit the Wind” about the trial of John Scopes in 1925; Scopes was a high school science teacher who was teaching his students about the theory of evolution; but the state of Tennessee had passed a law against teaching evolution, so Scopes was put on trial.
For most people, creationism not a burning issue.
After all these centuries, Pope John Paul II ordered a review of the trial of Galileo. He wanted to know whether the Inquisition had been mistaken in their action: If they made a bad decision, why?

10. Any Ideas? What about Creationism vs. Darwin’s theory?
There is still conflict about whether or not certain topics should be taught in school.
Pope John Paul II ordered a review of the trial of Galileo. Did the Inquisition make mistakes?

11. Isaac Newton Known for discovering gravity and developing calculus.
Part 5 -- Newton (15 minutes)
Finally, in this historical lecture, Isaac Newton.
Take a moment to make sure this is on your chart!!

12. F a = m r m Gm F = Isaac Newton
Newton solved the premier scientific problem of his time --- to explain the motion of the planets.
To explain the motion of the planets, Newton developed three ideas: m F a =
The laws of motion
The theory of universal gravitation
Calculus, a new branch of mathematics 2 1 r m Gm F =
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Newton based his work on the discoveries of his predecessors. This Newton quotation is taken from a letter to Robert Hooke, another physicist of the time of Newton. {READ quotation}
“If I have been able to see farther than others it is because I stood on the shoulders of giants.”
--- Newton’s letter to Robert Hooke,
perhaps referring to Galileo and Kepler

13. Newton’s Theory of Universal Gravitation
Newton and the Apple
Newton asked good questions  the key to his success.
Observing Earth’s gravity acting on an apple, and seeing the moon, Newton asked whether the Earth’s gravity extends as far as the moon.
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7/14/06
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