1. Universe Tenth Edition Chapter 12: Jupiter and Saturn: Lords of the Planets Roger Freedman Robert Geller William Kaufmann III

2. 12-1: Jupiter and Saturn are the most massive planets in the solar system

3. 12-1 What observations from Earth reveal about Jupiter and Saturn 12-2 How Jupiter and Saturn rotate differently from terrestrial planets like Earth 12-3 The nature of the immense storms seen in the clouds of Jupiter and Saturn 12-4 How the internal heat of Jupiter and Saturn drives activity in their atmospheres 12-5 What the Galileo space probe revealed about Jupiter ’ s atmosphere 12-6 How the shapes of Jupiter and Saturn indicate the sizes of their rocky cores By reading this chapter, you will learn

4. 12-7 How Jupiter and Saturn ’ s intense magnetic fields are produced by an exotic form of hydrogen 12-8 The overall structure and appearance of Saturn ’ s ring system 12-9 What kinds of particles form the rings of Jupiter and Saturn 12-10 How spacecraft observations revealed the intricate structure of Saturn ’ s rings 12-11 How Saturn ’ s rings are affected by the presence of several small satellites By reading this chapter, you will learn

9. Jupiter and Saturn as Viewed from Earth

10. Jupiter as Viewed from Space

11. Saturn as Viewed from Space

12. Solid Rotation versus Differential Rotation 12-2: Unlike the terrestrial planets, Jupiter and Saturn exhibit differential rotation

13. Solid Rotation versus Differential Rotation

14. Jupiter’s Changing Appearance 12-3: Spacecraft images show remarkable activity in the clouds of Jupiter and Saturn

15. Jupiter’s Changing Appearance

22. The Great Red Spot

24. Creating Red Spot Jr.

26. Dark Belt Fades on Jupiter

27. A New Storm on Saturn

28. Hexagonal Pattern around Saturn’s North Pole

31. The Upper Atmospheres of Jupiter and Saturn 12-4: The internal heat of Jupiter and Saturn has a major effect on the planets’ atmospheres

32. The Upper Atmospheres of Jupiter and Saturn

33. Original Model of Jupiter’s Belts and Zones

34. The Galileo Probe Enters Jupiter’s Atmosphere 12-5: The Galileo space probe explored Jupiter’s deep atmosphere

35. The Internal Structures of Jupiter and Saturn 12-6: The oblateness of Jupiter and Saturn reveals their rocky cores

36. Jupiter’s Magnetosphere 12-7: Metallic hydrogen inside Jupiter and Saturn endows the planets with strong magnetic fields

37. Aurorae on Jupiter and Saturn

38. Saturn’s System of Rings 12-8: Earth-based observations reveal three broad rings encircling Saturn

39. The Changing Appearance of Saturn’s Rings

40. Jupiter’s Main Ring 12-9: Saturn’s rings are composed of numerous icy fragments, while Jupiter’s rings are made of small rocky particles

41. Planetary Rings and the Roche Limit

43. Details of Saturn’s Rings 12-10: Saturn’s rings consist of thousands of narrow, closely spaced ringlets

44. Details of Saturn’s F Ring

45. The View from the Far Side of Saturn’s Rings

46. Color Variations in Saturn’s Rings

47. The Arrangement of Saturn’s Rings

48. Backlit Saturn

49. Saturn’s F Ring and Its Two Shepherds

50. Daphnis and the Keeler Gap 12-11: Saturn’s inner satellites affect the appearance and structure of its rings

51. Daphnis and the Keeler Gap

52. Cassini close up image of Saturn’s Rings

53. Key Ideas Composition and Structure: Jupiter and Saturn are both much larger than Earth. Each is composed of 71% hydrogen, 24% helium, and 5% all other elements by mass. Both planets have a higher percentage of heavy elements than does the Sun. Jupiter probably has a rocky core several times more massive than the Earth. The core is surrounded by a layer of liquid “ ices ” (water, ammonia, methane, and associated compounds). On top of this is a layer of helium and liquid metallic hydrogen and an outermost layer composed primarily of ordinary hydrogen and helium. All of Jupiter ’ s visible features are near the top of this outermost layer.

54. Key Ideas Saturn ’ s internal structure is similar to that of Jupiter, but its core makes up a larger fraction of its volume and its liquid metallic hydrogen mantle is shallower than that of Jupiter. Jupiter and Saturn both rotate so rapidly that the planets are noticeably flattened. Both Jupiter and Saturn emit more energy than they receive from the Sun. Presumably both planets are still cooling.

55. Key Ideas Atmospheres: The visible “ surfaces ” of Jupiter and Saturn are actually the tops of their clouds. The rapid rotation of the planets twists the clouds into dark belts and light zones that run parallel to the equator. Strong zonal winds run along the belts and zones. The outer layers of both planets ’ atmospheres show differential rotation: The equatorial regions rotate slightly faster than the polar regions. The colored ovals visible in the Jovian atmosphere represent gigantic storms. Some, such as the Great Red Spot, are quite stable and persist for many years. Storms in Saturn ’ s atmosphere seem to be shorter-lived.

56. Key Ideas There are presumed to be three cloud layers in the atmospheres of Jupiter and Saturn. The reasons for the distinctive colors of these different layers are not yet known. The cloud layers in Saturn ’ s atmosphere are spread out over a greater range of altitude than those of Jupiter, giving Saturn a more washed-out appearance. Saturn ’ s atmosphere contains less helium than Jupiter ’ s atmosphere. This lower abundance may be the result of helium raining downward into the planet. Magnetic Fields and Magnetospheres: Jupiter has a strong magnetic field created by currents in the metallic hydrogen layer. With less liquid metallic hydrogen, Saturn’s magnetic field is much weaker than Jupiter’s.

57. Key Ideas Rings: Saturn is circled by a system of thin, broad rings lying in the plane of the planet ’ s equator. This system is tilted away from the plane of Saturn ’ s orbit, which causes the rings to be seen at various angles by an Earth-based observer over the course of a Saturnian year. Structure of the Rings: Saturn has three major, broad rings (A, B, and C) that can be seen from Earth. Other, fainter rings were found by the Voyager spacecraft.

58. Key Ideas The principal rings of Saturn are composed of numerous particles of ice and ice-coated rock ranging in size from a few micrometers to about 10 m. Most of the rings exist inside the Roche limit of Saturn, where disruptive tidal forces are stronger than the gravitational forces attracting the ring particles to each other. Each of Saturn ’ s major rings is composed of a great many narrow ringlets. The faint F ring, which is just outside the A ring, is kept narrow by the gravitational pull of shepherd satellites. Jupiter ’ s faint rings are composed of a relatively small amount of small, dark, rocky particles that reflect very little light.