1. Models of the Solar System, Gravitation and the motion of the Planets – A.K.A DEAD WHITE GUYS WEEK!

2. Planets were often called wandering stars because they seem to slowly move from one constellation to the next. West East South

3. Retrograde motion Models of the universe MUST adequately describe this retrograde motion!!!

4. Philosophical Ideas The heavens represent perfection. The heavens are immutable. The circle is the perfect shape. All heavenly motions must be circular.

5. The astronomer must try his utmost to explain celestial motions by the simplest possible hypothesis; but if he fails to do so, he must choose whatever other hypotheses meet the case. -Ptolemy of Alexandria (140 A.D.)

6. Copernicus devised the first comprehensive heliocentric cosmogony to successfully explain retrograde motion Ptolemy was -

7. Ptolemy was : 1.Polish 2.Danish 3.Italian 4.German 5.Greek

8. Ptolemy tried to crate a model that would account for retrograde motion. He placed the planets in orbits (deferments) on orbits (epicycles) all around the Earth

9. Ptolemy’s Epicycles Epicycle Deferent Earth

10. Ptolemy’s Epicycles

33. Where is retrograde motion occurring? Planet’s Path

34. Ptolemy’s Epicycles Where is retrograde motion? Planet’s Path

35. For most of human history, we have thought the universe was geocentric

36. “A system of this sort seemed neither sufficiently absolute nor sufficiently pleasing to the mind.” --Copernicus On the Ptolemaic system:

37. Why heliocentric NOW?? Renaissance art literature medicine exploration

38. Copernicus (1473 – 1543 AD) was : 1.Polish 2.Danish 3.Italian 4.German 5.Greek

39. Copernicus (1473 – 1543 AD) is known for : 1.First observations of the sun 2.First sun centered model of the solar system or universe 3.The world’s best naked-eye astronomical observations in history 4.Creating first a theoretical model to explain planetary motions 5.Creating first a theoretical model for explaining gravity

40. Copernicus (1473 – 1543 AD) is known for - 1.First observations of the sun 2.First sun centered model of the solar system or universe 3.The world’s best naked-eye astronomical observations in history 4.Creating first a theoretical model to explain planetary motions 5.Creating first a theoretical model for explaining gravity

41. Copernicus (1473 – 1543 AD) - 1.Probably died a virgin 2.Was a priest and Lawyer 3.Had artificial wooden and silver noses 4.Probably died of Mercury poising 5.Rumored to have died of a bladder burst 6.Was blind at the time of his death 7.Was labeled a heretic by the church

42. Copernicus (1473 – 1543 AD) - 1.Probably died a virgin 2.Was a priest and Lawyer 3.Had artificial wooden and silver noses 4.Probably died of Mercury poising 5.Rumored to have died of a bladder burst 6.Was blind at the time of his death 7.Was labeled a heretic by the church

44. Copernicus devised the first comprehensive heliocentric cosmogony to successfully explain retrograde motion Retrograde motion is an apparent motion caused when one planets moves from being behind another planet to being in front of the other planet.

45. Copernicus devised the first comprehensive heliocentric cosmogony to successfully explain retrograde motion Let’s watch a movie of this motion.

46. To demonstrate that the appearances are saved by assuming the Sun at the center and the Earth in the heavens is not the same thing as to demonstrate that in fact the Sun is in the center and the Earth in the heavens. I believe that the first demonstration may exist, but I have grave doubts about the second. --Cardinal Bellarmine (1615)

47. Tycho Brahe (1546-1601)

48. Cross-Tab Label Tycho Brahe (1546-1601) was - 1.Polish 2.Danish 3.Italian 4.German 5.Greek

49. Tycho Brahe (1546-1601) - 1.Probably died a virgin 2.Was a priest and Lawyer 3.Had artificial wooden and silver noses 4.Probably died of Mercury poising 5.Rumored to have died of a bladder burst 6.Was blind at the time of his death 7.Was labeled a heretic by the church

50. Tycho Brahe (1546-1601) - 1.Probably died a virgin 2.Was a priest and Lawyer 3.Had artificial wooden and silver noses 4.Probably died of Mercury poising 5.Rumored to have died when his bladder burst 6.Was blind at the time of his death 7.Was labeled a heretic by the church

51. Tycho Brahe (1546-1601) is known for - 1.First telescope observations of the sun 2.First sun centered scientific model of the solar system or universe 3.Being the world’s best naked- eye astronomer 4.Creating first a theoretical model to explain planetary motions 5.Creating first a theoretical model for explaining gravity

52. Tycho Brahe (1546-1601) is known for - 1.First telescope observations of the sun 2.First sun centered scientific model of the solar system or universe 3.Being the world’s best naked- eye astronomer 4.Creating first a theoretical model to explain planetary motions 5.Creating first a theoretical model for explaining gravity

53. Tycho Brahe (1546-1601) What do we mean by “Greatest Naked-eye Astronomer?”

54. No telescope!!

55. Scientists use parallax to measure distances.

57. Tycho Brahe measured distances using parallax that disproved ancient ideas about the heavens He observed a supernova in 1572 and with this showed that the heavens were both changing and had a dimension of distance; this troubled scholars who previously thought the heavens were unchanging. He showed that comets were objects that occurred in the region of the planets, not in Earth’s atmosphere.

58. Johannes Kepler 1571 - 1630

59. Cross-Tab Label Johannes Kepler 1571 - 1630 was : 1.Polish 2.Danish 3.Italian 4.German 5.Greek

60. Johannes Kepler 1571 - 1630 - 1.Probably died a virgin 2.Was a priest and Lawyer 3.Had artificial wooden and silver noses 4.Probably died of Mercury poising 5.Rumored to have died when his bladder burst 6.Was blind at the time of his death 7.Was labeled a heretic by the church

61. Johannes Kepler 1571 - 1630 - None of these. He was a deeply religious man and a family man. He was rumored to have hated Tycho Brahe and was in the relationship for the data. With that data he changed the understanding of motion of heavenly bodies forever. He was also a writer, who wrote children stories about the heavens.

62. Cross-Tab Label Johannes Kepler 1571 - 1630 is Known for - 1.First telescope observations of the sun 2.First sun centered scientific model of the solar system or universe 3.Being the world’s best naked-eye astronomer 4.Creating first a theoretical model to explain planetary motions 5.Creating first a theoretical model for explaining gravity

63. Johannes Kepler 1571 - 1630 is Known for - 1.First telescope observations of the sun 2.First sun centered scientific model of the solar system or universe 3.Being the world’s best naked-eye astronomer 4.Creating first a theoretical model to explain planetary motions 5.Creating first a theoretical model for explaining gravity

64. Johannes Kepler 1571 – 1630 Kepler’s Three Laws of Planetary Motion

65. Eccentricity, e how squashed or out of round the ellipse is a number ranging from 0 for a circle to 1 for a straight line e = 0.02 e = 0.7 e = 0.9

66. Kepler’s First Law: The orbit of a planet about the Sun is an ellipse with the Sun at one focus.

67. What is the shape of Earth’s orbit around the Sun? Earth, e = 0.016

69. SECOND LAW A line drawn from the planet to the Sun sweeps out equal areas in equal times

70. Kepler’s Second Law: A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.

71. Kepler's Second Law Movie http://bcs.whfreeman.com/universe6e/pages/bcs-main.asp?v=category&s=00110&n=01000&i=04110.07&o=|04000|01000|&ns=0

72. SECOND LAW A line drawn from the planet to the Sun sweeps out equal areas in equal times orbital speed is not constant for an ellipse only for a circle planets move faster when near the Sun (perihelion) planets move slower when they are far from the Sun (aphelion)

73. THIRD LAW The size of the orbit determines the orbital period –planets that orbit near the Sun orbit with shorter periods than planets that are far from the Sun a 3 AU = P 2 years

74. THIRD LAW The size of the orbit determines the orbital period –planets that orbit near the Sun orbit with shorter periods than planets that are far from the Sun

75. Kepler’s Third Law: The square of a planet’s sidereal (orbital) period is proportional to the cube of the length of its orbit’s semimajor axis (p 2  a 3 ).

76. The Second and Third Laws The Second Law tells us what a particular planet does when it orbits a Star –The planet will move faster when it is close to the Sun and slower when it is farther from the Sun The Third Law how the orbital periods are related to the orbital distances for all the planets in the Solar System –planets that are in an orbit located near the Sun have short orbital periods –planets that are in an orbit located far from the Sun have long orbital periods

77. SECOND LAW The speed a planet travels during its orbit is related to the distance from the star –When the planet is near the sun the planet goes faster than when the planet is farther from the sun Planet travels fast here Planet travels slow here

78. THIRD LAW The size of the orbit determines the orbital period –planets that orbit near the Sun orbit with shorter periods than planets that are far from the Sun p = 1 year p = ~ 12 years

79. THIRD LAW The size of the orbit determines the orbital period –planets that orbit near the Sun orbit with shorter periods than planets that are far from the Sun –MASS DOES NOT MATTER Both have p = 1 year

80. The Second and Third Laws The Second Law tells us what a particular planet does when it orbits a Star –The planet will move faster when it is close to the Sun and slower when it is farther from the Sun The Third Law how the orbital periods are related to the orbital distances for all the planets in the Solar System –planets that are in an orbit located near the Sun have short orbital periods –planets that are in an orbit located far from the Sun have long orbital periods

81. Kepler’s Laws - Lecture Tutorials: One in the book (pg 53-56) one is a Handout. Work with a partner! Read the instructions and questions carefully. Discuss the concepts and your answers with one another. Come to a consensus answer you both agree on. If you get stuck or are not sure of your answer, ask another group. If you get really stuck or don’t understand what the Lecture Tutorial is asking, ask one of us for help.

82. Homework #3 Kepler’s Laws – Ranking Tasks handout

83. According to Kepler’s second law, a planet with an orbit like Earth’s would: 1. move faster when further from the Sun. 2. move slower when closer to the Sun. 3. experience a dramatic change in orbital speed from month to month. 4. experience very little change in orbital speed over the course of the year. 5. none of the above.

84. Which of the following best describes what would happen to a planet’s orbital speed if it’s mass were doubled but it stayed at the same orbital distance? 1. It would orbit half as fast. 2. It would orbit less that half as fast. 3. It would orbit twice as fast. 4. It would orbit more than twice as fast. 5. It would orbit with the same speed.

85. Kepler’s second law says “a line joining a planet and the Sun sweeps out equal areas in equal amounts of time.” Which of the following statements means nearly the same thing? 1. Planets move fastest when they are moving toward the Sun. 2. Planets move equal distances throughout their orbit of the Sun. 3. Planets move slowest when they are moving away from the Sun. 4. Planets travel farther in a given time when they are closer to the Sun. 5. Planets move the same speed at all points during their orbit of the Sun.

86. If a small weather satellite and the large International Space Station are orbiting Earth at the same altitude above Earth’s surface, which of the following is true? 1. The large space station has a longer orbital period. 2. The small weather satellite has a longer orbital period. 3. Each has the same orbital period