1. © 2011 Pearson Education, Inc. Units of Chapter 2 2.1 Ancient Astronomy 2.2 The Geocentric Universe 2.3 The Heliocentric Model of the Solar System The Foundations of the Copernican Revolution 2.4 The Birth of Modern Astronomy

2. © 2011 Pearson Education, Inc. Units of Chapter 2, continued 2.5 The Laws of Planetary Motion Some Properties of Planetary Orbits 2.6 The Dimensions of the Solar System 2.7 Newton’s Laws 2.8 Newtonian Mechanics Weighing the Sun

3. © 2011 Pearson Education, Inc. White Board Question What are some ancient structures that people used the sun and stars to help keep track of time and seasons?

4. © 2011 Pearson Education, Inc. 2.1 Ancient Astronomy Ancient civilizations observed the skies Many built structures to mark astronomical events Summer solstice sunrise at _____________:

5. © 2011 Pearson Education, Inc. 2.1 Ancient Astronomy Spokes of the _________________________in Wyoming are aligned with the rising and setting of the Sun and other stars

6. © 2011 Pearson Education, Inc. 2.1 Ancient Astronomy This temple at _______________, in Mexico, has many windows that are aligned with astronomical events

7. © 2011 Pearson Education, Inc. 2.2 The Geocentric Universe Earth based Ancient astronomers observed: Five planets:

8. © 2011 Pearson Education, Inc. 2.2 The Geocentric Universe Sun, Moon, and stars all have simple movements in the sky Planets: Move with respect to fixed stars Change in brightness Change speed Undergo retrograde motion

9. © 2011 Pearson Education, Inc. Golden Age 600 BC-AD 150 Aristotle _______ philosopher (384-322 BC) Earth is _____________ Casts a curved shadow when passes between _________ and ______ His belief was abandoned during the Middle Ages

10. © 2011 Pearson Education, Inc. _________________ 276-194 BC First successful attempt to figure out the size of the earth ____________________ 2 nd Century BC Divided stars into six groups according to brightness Method for predicting lunar eclipses

11. © 2011 Pearson Education, Inc. ________centric model _______________________ orbit the earth _________________(stars) orbits the earth Incorrect

12. © 2011 Pearson Education, Inc. 2.2 The Geocentric Universe Earliest models had ____________________ at center of solar system Needed lots of complications to accurately track planetary motions

13. © 2011 Pearson Education, Inc. Carl Sagan on epicycles http://www.dailymotion.com/vide o/xerwsh_carl-sagan-videos- epicycles-of-ptol_tech Take notes:

14. © 2011 Pearson Education, Inc. _____________centric Model First heliocentric astronomer-- Aristarchus (Greek 312-230 BC) Earth and other planets orbit the sun

15. © 2011 Pearson Education, Inc. Heliocentric vs. Geocentric Model Model Location of Earth Location of Sun Who supports __________ Center of the universe Orbits _______ Heliocentric_________ ________ of the universe

16. © 2011 Pearson Education, Inc. White board question On your white board make a Venn Diagram comparing Heliocentric and Geocentric views of the universe.

17. Ptolemaic System Claudius ______________ wrote a 13 volume work on Greek astronomy ___________centric, used ___________ to explain the varying brightness of planets and planet retrograde motions Used mathematical terms to explain the heavenly bodies

18. © 2011 Pearson Education, Inc. 2.3 The _____________________ Model of the Solar System This figure shows retrograde motion of Mars. _______________ is at center of solar system. Only Moon orbits around Earth; planets orbit around Sun.

19. © 2011 Pearson Education, Inc. Understanding retrograde motion http://astro.unl.edu/classaction/animations/re naissance/retrograde.htmlhttp://astro.unl.edu/classaction/animations/re naissance/retrograde.html Interactive –http://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600: :/sites/dl/free/0072482621/78780/Retro_Nav.swf:: Retrograde%20Motionhttp://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600: :/sites/dl/free/0072482621/78780/Retro_Nav.swf:: Retrograde%20Motion

20. © 2011 Pearson Education, Inc. White board Explain retrograde motion to your neighbor, see if you can write it out

21. © 2011 Pearson Education, Inc. Discovery 2-1: The Foundations of the Copernican Revolution 1. ____________ is not at the center of everything. 2. Center of Earth is the center of _________ orbit. 3. All _________________revolve around the Sun. 4.The ________________ are very much farther away than the Sun. 5.The apparent movement of the stars around the Earth is due to the Earth’s __________________. 6.The apparent movement of the Sun around the Earth is due to the Earth’s __________________. 7.______________________motion of planets is due to Earth’s motion around the Sun.

22. © 2011 Pearson Education, Inc. 2.4 The Birth of Modern Astronomy _________________________ invented around 1600 ___________________ built his own, made observations: Moon has mountains and valleys Sun has ___________, and rotates ______________has moons Venus has ________________

23. Galileo and Venus How did Venus retrograde motion definitely prove that the sun is at the center of the solar system? Turn to your table group and see if you can figure it out

24. © 2011 Pearson Education, Inc. 2.4 The Birth of Modern Astronomy _______________ cannot be explained by geocentric model

25. _______________ 1546-1601 Denmark Developed instruments to measure the locations of heavenly bodies Collected a vast amount of data that Keplar was able to use to build his laws of planetary motion

26. © 2011 Pearson Education, Inc. 2.5 The Laws of Planetary Motion ___________________ were derived using observations made by Tycho Brahe

27. Johannes Kepler 1571-1630 Three laws of planetary motion –Kepler observed: Mars orbit was elliptical As Mars approaches the sun it speeds up and slows down as it goes away from the sun

28. Three laws of planetary motion 1.The path of each planet around the sun is an ellipse with the sun at one focus. 2.Each planet revolves around the sun so that it sweeps over equal areas in equal amounts of time causing it to travel more rapidly in areas closer to the sun. 3.The square of the orbital period is proportional to the cube of its distance from the sun.

29. © 2011 Pearson Education, Inc. 2.5 The Laws of Planetary Motion Law 1. Planetary orbits are ________________, Sun at on a

30. © 2011 Pearson Education, Inc. Time to try it on your own An ellipse can be drawn with the aid of a string, a pencil, and two thumbtacks. The wider the separation of the foci, the more elongated, or eccentric, is the ellipse. In the special case where the two foci are at the same place, the curve drawn is a circle.

31. © 2011 Pearson Education, Inc. 2.5 The Laws of Planetary Motion Law 2. Imaginary line connecting Sun and planet sweeps out _________________________

32. Keplar’s 2 nd law http://www.youtube.com/watch?v=5a2mcE- tzKE

33. © 2011 Pearson Education, Inc. 2.5 The Laws of Planetary Motion Law 3. Square of ____________ of planet’s orbital motion is proportional to cube of _______________________________________

34. © 2011 Pearson Education, Inc. More Precisely 2-1: Some Properties of Planetary Orbits ____________________: closest approach to Sun __________________: farthest distance from Sun

36. Another way to say them The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The Law of _________________________) 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 ___________________) http://www.physicsclassroom.com/mmedia/circmot/ksl.cfm http://www.physicsclassroom.com/mmedia/circmot/ksl.cfm 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 ________________________)

37. Easy math If planet A is 4 units from the sun then what is its orbital period. (a 3 = p 2)

38. Keplar’s laws http://www.youtube.com/watch?v=5a2mcE- tzKE http://www.youtube.com/watch?v=GcKiG- CuvtA

39. Let’s watch different planets in action http://astro.unl.edu/classaction/animations/ renaissance/kepler.htmlhttp://astro.unl.edu/classaction/animations/ renaissance/kepler.html

40. __________________ Mathematician Invented calculus to solve the gravity

41. © 2011 Pearson Education, Inc. 2.7 Newton’s Laws ____________________ ____________________ explain how objects interact with the world and with each other.

42. Newton: Three laws of motion Law 1: An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law is often called “________________________". http://teachertech.rice.edu/Participants/lo uviere/Newton/law1.html

43. White board question If everything in an airplane is traveling at the same speed when do you feel the motion?

44. Law 2 Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). http://teachertech.rice.edu/Participants/lou viere/Newton/law2.htmlhttp://teachertech.rice.edu/Participants/lou viere/Newton/law2.html Force=____________________________ Force g =mass x gravitational acceleration

45. Definitions ___________________ is an intrinsic property of an object and remains the same independent of where it is in the universe _________________is the downward force experienced by an object as a result of gravitational interaction

46. A little math If Marvin the Martian is 100 lbs on Earth how much would he weigh on the moon if the surface gravity is 17% of that on Earth? Weight=mass x gravitational acceleration Or weight = weight on earth x specific gravity Now see if you can figure it out W= 100 lbs x.17=17 lbs.

47. Law 3 For every action there is an _____________and _______________ re-action. http://teachertech.rice.edu/Participants/lou viere/Newton/law3.htmlhttp://teachertech.rice.edu/Participants/lou viere/Newton/law3.html

48. Sir Isaac Newton 1642-1727

49. Newton in a nutshell Without the influence of ____________, planets would move in a straight line out into space. The tendency of planets to remain in a straight line and the force of ________________ result in elliptical patterns

50. Using Newton’s gravity Basically Force is proportional to the product of the mass of two objects/distance between them squared so: If the mass doubles the force ____________ but if the distance doubles then you have ________ the force. So you can figure weight of an object if you know the distance from earth

51. © 2011 Pearson Education, Inc. 2.7 Newton’s Laws Gravity On the Earth’s surface, __________________ _________________ is approximately constant, and directed toward the center of Earth

52. © 2011 Pearson Education, Inc. 2.7 Newton’s Laws Gravity The constant G is called the ______________________________________; it is measured experimentally and found to be G = 6.67 x 10 -11 N m 2 /kg 2

53. © 2011 Pearson Education, Inc. But let’s look at an easier way F g  m 1 m 2 / d 2 The force of gravity is proportional to the product of the mass of the two objects divided by the distance squared

54. White board problem If Marvin is 36 lbs how much is his weight if he is at 2r (distance from Earth) Weight = 36/2 2 36/4=9lbs

55. So if this is true and astronauts at the space station are still within the earth’s gravity, why do they experience weightlessness??? http://www.youtube.com/watch?v =2V9h42yspbo

56. © 2011 Pearson Education, Inc. 2.8 Newtonian Mechanics _________________: the speed necessary for a projectile to completely escape a planet’s _________________ ________________. With a lesser speed, the projectile either returns to the planet or stays in orbit.

57. So what did Einstein have to say about gravity? But what is gravity, what is it that attracts to objects to one another? http://www.youtube.com/watch?v=O-p8yZYxNGchttp://www.youtube.com/watch?v=O-p8yZYxNGc http://www.youtube.com/watch?v=DbhuRcmSkMg&feature=rel ated

58. Gravity as Curved Space

59. Curved space Einstein noticed ___________________. A beam of light follows the curvature of space Planets follow the _________________ so if gravity has curvature then anything with mass will curve the space around it