Copyright © 2010 Pearson Education, Inc. and R. Fisher Copyright © 2010 Pearson Education, Inc. Lecture Outline Chapter 1 The Copernican Revolution

Copyright © 2010 Pearson Education, Inc. and R. Fisher In the news supercluster-laniakea-milky-way- home.htmlhttp:// supercluster-laniakea-milky-way- home.html

Copyright © 2010 Pearson Education, Inc. and R. Fisher 12 sept: Chapter 1 The Copernican Revolution

Copyright © 2010 Pearson Education, Inc. and R. Fisher Preview the chapter…. The Motions of the Planets The Birth of Modern Astronomy The Laws of Planetary Motion Newton’s Laws Summary of Chapter 1 Units of Chapter 1

Copyright © 2010 Pearson Education, Inc. and R. Fisher The Sun, Moon, and stars all have simple movements in the sky, consistent with an Earth-centered system. But the Planets: (Show on Stellarium) Move with respect to fixed stars Change in brightness Change speed Have retrograde motion Are difficult to describe in earth-centered system 1.1 The Motions of the Planets

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1.1 The Motions of the Planets A basic geocentric model, showing an epicycle (used to explain planetary motions)

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1.1 The Motions of the Planets Lots of epicycles were needed to accurately track planetary motions, especially retrograde motions. This is Ptolemy's model.

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1.1 The Motions of the Planets A heliocentric (Sun-centered) model of the solar system easily describes the observed motions of the planets, without excess complication. So, what is the primary advantage of the heliocentric model?..

Copyright © 2010 Pearson Education, Inc. and R. Fisher *13 sept; 1.2 The Birth of Modern Astronomy Observations of Galileo: The Moon has mountains, valleys, and craters. The Sun has imperfections, and it rotates. Jupiter has moons. Venus has phases. All these were in contradiction to the general belief that the heavens were constant, perfect, and immutable.

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1.2 The Birth of Modern Astronomy The phases of Venus are impossible to explain in the Earth-centered model of the solar system.

Copyright © 2010 Pearson Education, Inc. and R. Fisher The birth of modern astronomy WP9zu4W8https:// WP9zu4W8 Watch until 10:45.

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1. Planetary orbits are ellipses, Sun at one focus. Kepler’s laws: 1.3 The Laws of Planetary Motion

Copyright © 2010 Pearson Education, Inc. and R. Fisher 2. Imaginary line connecting Sun and planet sweeps out equal areas in equal times. Kepler’s laws: **1.3 The Laws of Planetary Motion When an orbiting planet or comet is near the sun, it goes fast, and when it’s far away, it goes slowly.

Copyright © 2010 Pearson Education, Inc. and R. Fisher 3. Square of period of planet’s orbital motion is proportional to cube of semimajor axis. Kepler’s laws: 1.3 The Laws of Planetary Motion The period of a planet goes up as the radius of the planet increases Compare this to Kepler’s second law.

Copyright © 2010 Pearson Education, Inc. and R. Fisher Who was Kepler? The greatest astronomer. Born Worked for Tycho Brahe (“teesho”) Analyzed motion of the planets, worked out laws of planetary motion a good and interesting 20 min video of this history plus

Copyright © 2010 Pearson Education, Inc. and R. Fisher From this video, know Aritotle Ptolomy Renaissance Copernicus Tycho brahe Kepler Galileo Newton

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1.3 The Laws of Planetary Motion The Dimensions of the solar system The distance from Earth to the Sun is called an astronomical unit. Its actual length may be measured by bouncing a radar signal off Venus and measuring the transit time.

Copyright © 2010 Pearson Education, Inc. and R. Fisher Newton’s laws of motion explain how objects interact with the world and with each other. Newton’s first law: An object at rest will remain at rest, and an object moving in a straight line at constant speed will not change its motion, unless an external force acts on it. 1.4 Newton’s Laws

Copyright © 2010 Pearson Education, Inc. and R. Fisher Newton’s second law: When a force is exerted on an object, its acceleration is inversely proportional to its mass: a = F/m Newton’s third law: know this one!!!! When object A exerts a force on object B, object B exerts an equal and opposite force on object A. 1.4 Newton’s Laws

Copyright © 2010 Pearson Education, Inc. and R. Fisher Gravity On Earth’s surface, the acceleration due to gravity is approximately constant, and directed toward the center of Earth. 1.4 Newton’s Laws

Copyright © 2010 Pearson Education, Inc. and R. Fisher Gravity For two massive objects, the gravitational force is proportional to the product of their masses divided by the square of the distance between them. 1.4 Newton’s Laws The closer they are, or the bigger (more massive) they are, the harder they pull on each other.

Copyright © 2010 Pearson Education, Inc. and R. Fisher Gravity The gravitational pull of the Sun keeps the planets moving in their orbits. 1.4 Newton’s Laws Compare to a spinning ball on string….

Copyright © 2010 Pearson Education, Inc. and R. Fisher 1.4 Newton’s Laws Two or more Massive objects orbit around each other. look at system/my-solar-system_en.html and see binary star or double double to see various types of orbit. system/my-solar-system_en.html Or look at and-orbits to see earth wobble the sun. and-orbits

Copyright © 2010 Pearson Education, Inc. and R. Fisher Kepler’s laws are a consequence of Newton’s laws. 1.4 Newton’s Laws

Copyright © 2010 Pearson Education, Inc. and R. Fisher 18 sept. Quiz on chapter 2 1.The shape of every orbit is a.Circle b. square c. parabola d. ellipse 2.Which was NOTan observation of Galileo? a.The Moon has mountains, valleys, and craters. B. The Sun has imperfections, and it rotates. C. Jupiter has moons. D. Venus has moons 3.Which of these people was NOT part of the Copernican revolution a.Copernicus b. Aristotle c. Kepler d. Newton 4.What is the force that holds all planets, moons, comets, asteroids, galaxies, and stars in their orbits? a. Gravity b. Magnetism c. Jedi d. Mass

Copyright © 2010 Pearson Education, Inc. and R. Fisher 18 Sept 2015 Quiz on Stelarium Find your object Any moons? Their period Magnitude, phases Look at variation with time Why change size Moon on sept 27, 9:40pm Turn on equatorial grid Find your zodiac constellation Where was the moon when you were born?

Copyright © 2010 Pearson Education, Inc. and R. Fisher First models of solar system were geocentric, but couldn't easily explain retrograde motion. Heliocentric model does. Galileo's observations supported heliocentric model. Kepler found three empirical laws of planetary motion from observations. Summary of Chapter 1

Copyright © 2010 Pearson Education, Inc. and R. Fisher The varieties of orbital motion system/my-solar-system_en.htmlhttp://phet.colorado.edu/sims/my-solar- system/my-solar-system_en.html Look at the range of possibilities Check: why are only stable orbits present in our solar system & galaxy? Are all orbits stable? Examples….

Copyright © 2010 Pearson Education, Inc. and R. Fisher Laws of Newtonian mechanics explained Kepler’s observations. Gravitational force between two masses is proportional to the product of the masses, divided by the square of the distance between them. Summary of Chapter 1, cont.

Copyright © 2010 Pearson Education, Inc. and R. Fisher Update on New Horizons

Copyright © 2010 Pearson Education, Inc. and R. Fisher Show this tool in google earth

Copyright © 2010 Pearson Education, Inc. and R. Fisher NY Times yesterd ay

Copyright © 2010 Pearson Education, Inc. and R. Fisher Practice for exam 1 1) In an annular eclipse, A) the Moon is totally blocked by the Earth. B) the Sun is partially blocked by the Earth. C) the Moon appears as a thin, bright ring. D) the Sun appears as a thin, bright ring. E) the Sun is totally blocked by the Moon. 2) The interval from new Moon to first quarter is about a(n) A) month. B) day. C) hour. D) year. E) week. 3) Put these important scientists in proper order of when they lived and worked a. Galileo, b. Copernicus, c. Newton, d. Ptolomy, e. Kepler