Warm Up #7

1. Warm Up #7 • What changes in Europe led to the Scientific Revolution? • What is the difference between a geocentric and heliocentric view of the universe?

2. Great Astronomers of the Scientific Revolution Roaming Readers Create a chart like this one in your notebook. Fill in the chart as you visit each of the four stations.

3. Nicolaus Copernicus • B. 2/19/1473 in Poland • D. 5/24/1543 • Published his views on a heliocentric solar system shortly before his death • De RevolutionibusOrbiumCoelestium

4. Nicolaus Copernicus Nicolaus Copernicus was a Polish astronomer. He is best known for his astronomical theory that universe is helocentric. The major premises of Copernicus’s theory are that the earth rotates daily on its axis and revolves yearly around the sun. He argued that the planets also circle the sun, and that the earth precesses on its axis (wobbles like a top) as it rotates. Copernicus’s heliocentric theories of planetary motion accounted 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. 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 only ten scholars who supported Copernicus between 1543 and 1600. The most famous were Galileo and 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.

5. Tycho Brahe • B. 12/14/1546 in Denmark • D. 10/24/1601 • Precision measurements of celestial bodies • Assisted by Johannes Kepler

6. Tycho Brahe TychoBrahe was a Danish nobleman who identified the most precise instruments available for observing the heavens before the telescope. These instruments allowed him to determine the detailed motions of the planets. In particular, he gathered data on Mars, which would later help Keplerin his formulation of the laws of planetary motion because it would demonstrate that the orbit of Mars was not a circle but an ellipse. Brahe was by all accounts an extremely colorful character. He allegedly challenged a fellow student to a duel with swords in a dispute over who was the better mathematician. Brahe's nose was partially cut off, and he was said to wear a gold and silver replacement upon which he would continually rub oil. He fell out of favor when a new King came to power in 1588, and moved to Prague shortly thereafter. Kepler became Brahe's assistant when in Prague. Brahe made observations of a supernova in 1572 and a comet in 1577. His observations challenged Aristotle's view that the heavens were unchanging. Brahe proposed a model of the Solar System that was intermediate between the Ptolemaic and Copernican models (it had the Earth at the center). It proved to be incorrect, but was the most widely accepted model of the Solar System for a time. Brahe's ideas were not always correct, but the quality of the observations themselves was central to the development of modern astronomy.

7. Johannes Kepler • B. 12/27/1571 in the Holy Roman Empire • D. 11/15/1630 • Laws of Planetary Motion • The orbit of every planet is an ellipse with the Sun at one of the two foci. • A line joining a planet and the Sun sweeps out equal areas during equal intervals of time. • The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

8. Johannes Kepler Johannes Kepler was a German astronomer who discovered three major laws of planetary motion: (1) the planets move in elliptical (oval) orbits with the Sun at one focus; (2) An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of Equal Areas) (3) The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of Harmonies) He thought these rules reflected God’s design for the universe. Kepler’s discoveries supported and explainedNicolaus Copernicus’s Sun-centredsystem by adding new detail. Kepler also discovered how vision occurs, developed an explanation for the behaviour of light in the newly invented telescope, and offered a new theoretical foundation forastrology.

9. Galileo Galilei • B. 2/15/1564 in Italy • D. 1/8/1642 • Improvements to the telescope • Discovered many things, including 4 moons of Jupiter • Used observations from the telescope to support the heliocentric model

10. Galileo Challenges Accepted Beliefs The Italian scientist Galileo made many scientific advances that challenged classical ideas. He improved the telescope and produced the most powerful telescope of the day. He used his telescopes to study the sky. His observations clearly supported Copernicus’ ideas that the sun is the center of the solar system. He published about book about his findings called Dialogue Concerning the Two Chief World Systems: Ptolemaic & Copernican. This brought him into conflict with the Church. Copernicus’ view contradicted official Church beliefs that, according to the Bible, the universe was geocentric. Church leaders denounced Galileo. They forced him to publicly deny his findings. He lived comfortably under house arrest for the rest of his life. But Galileo knew he was right, and so did other scientists.

11. CH 13.2 Questions • How did the discovery of the Americas alter the views European scholars had of other Greek authorities? • How did the views of Copernicus and Keeper on the movement of the planets differ? • What did Tycho Brahe contribute to the Scientific Revolution? • What was Galileo's key contribution to the development of science? • What were Newton’s basic accomplishments? 6. How was Newton’s law of gravity connected to discoveries about the planets’ orbits?