1. Copyright © 2010 Pearson Education, Inc. Chapter 8 Moons, Rings, and Plutoids

2. Copyright © 2010 Pearson Education, Inc. Chapter 8 Moons, Rings, and Plutoids

3. Copyright © 2010 Pearson Education, Inc. Units of Chapter 8 The Galilean Moons of Jupiter The Large Moons of Saturn and Neptune The Medium-Sized Jovian Moons Planetary Rings Beyond Neptune Plutoids and the Kuiper Belt

4. Copyright © 2010 Pearson Education, Inc. As their distance from Jupiter increases, the four Galilean satellites show a consistent Question 1 a) increase in density. b) increase in size. c) decrease in cratering. d) decrease in density. e) amount of cratering.

5. Copyright © 2010 Pearson Education, Inc. As their distance from Jupiter increases, the four Galilean satellites show a consistent Question 1 a) increase in density. b) increase in size. c) decrease in cratering. d) decrease in density. e) amount of cratering. Like a miniature version of our solar system, Jupiter’s four large moons show a decrease in density as distance increases. Io is most dense of the four; Callisto is least dense.

6. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter All four Jovian planets have extensive moon systems, and more are continually being discovered. The Galilean moons of Jupiter are those observed by Galileo: Io, Europa, Ganymede, and Callisto.

7. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter This image shows Jupiter with two of its Galilean moons. Galilean Moons

8. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter The Galilean moons and their orbits

9. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter Their interiors

10. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter Io is the densest of Jupiter’s moons, and the most geologically active object in the solar system. It has many active volcanoes, some quite large. Io can change surface features in a few weeks. Io has no craters; they fill in too fast – Io has the youngest surface of any solar system object.

11. Copyright © 2010 Pearson Education, Inc. What is thought to cause Io’s volcanism? Question 3 a) Jupiter’s magnetosphere b) Jupiter’s rapid rotation c) tidal stress from Jupiter and Europa d) radioactive decay from its core e) Io’s large mass and tectonic activity

12. Copyright © 2010 Pearson Education, Inc. What is thought to cause Io’s volcanism? Question 3 a) Jupiter’s magnetosphere b) Jupiter’s rapid rotation c) tidal stress from Jupiter and Europa d) radioactive decay from its core e) Io’s large mass and tectonic activity Io is constantly “squeezed” by its huge neighbor as well as by companion moons, heating its interior.

13. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter Io is very close to Jupiter, and also experiences gravitational forces from Europa. The tidal forces are huge, and provide the energy for the volcanoes. Io Cutaway

14. Copyright © 2010 Pearson Education, Inc. The surface of which jovian moon most resembles the pack ice of the Arctic Ocean? Question 2 a) Europa b) Io c) Amalthea d) Ganymede e) Callisto

15. Copyright © 2010 Pearson Education, Inc. The surface of which jovian moon most resembles the pack ice of the Arctic Ocean? Question 2 Ice-filled surface cracks indicate an ocean may lie below. a) Europa b) Io c) Amalthea d) Ganymede e) Callisto

16. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter Europa has no craters; surface is water ice, possibly with liquid water below. Tidal forces stress and crack ice; water flows, keeping surface relatively flat. Galileo’s View

17. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter Ganymede is the largest moon in the solar system – larger than Pluto and Mercury. It has a history similar to Earth’s Moon, but with water ice instead of lunar rock. Galileo’s View

18. Copyright © 2010 Pearson Education, Inc. The Galilean Moons of Jupiter Callisto is similar to Ganymede; no evidence of plate activity.

19. Copyright © 2010 Pearson Education, Inc. The Large Moons of Saturn and Neptune Titan has been known for many years to have an atmosphere thicker and denser than Earth’s; mostly nitrogen and argon. Makes surface impossible to see; the picture at right was taken from only 4000 km away. Saturn Moon

20. Copyright © 2010 Pearson Education, Inc. The Large Moons of Saturn and Neptune Infrared image of Titan, showing detail, and possible icy volcano Few craters, consistent with active surface Complex chemical interactions in atmosphere

21. Copyright © 2010 Pearson Education, Inc. The Huygens lander took these images of the surface of Titan. The Large Moons of Saturn and Neptune Huygens Probe

22. Copyright © 2010 Pearson Education, Inc. The Large Moons of Saturn and Neptune Trace chemicals in Titan’s atmosphere make it chemically complex.

23. Copyright © 2010 Pearson Education, Inc. The Large Moons of Saturn and Neptune Triton is in a retrograde orbit; its surface has few craters, indicating an active surface. Nitrogen geysers have been observed on Triton, contributing to the surface features.

24. Copyright © 2010 Pearson Education, Inc. The Medium-Sized Jovian Moons Densities of these moons suggest that they are rock and water ice.

25. Copyright © 2010 Pearson Education, Inc. The Medium-Sized Jovian Moons Moons of Saturn, in natural color Note the similarities, as well as the large crater on Mimas.

26. Copyright © 2010 Pearson Education, Inc. The Medium-Sized Jovian Moons Moons of Uranus and Neptune

27. Copyright © 2010 Pearson Education, Inc. The Medium-Sized Jovian Moons Miranda shows evidence of a violent past, although the origin of the surface features is unknown.

28. Copyright © 2010 Pearson Education, Inc. Question 8 a) our Moon b) Phobos c) Europa d) Titan e) Triton Which moon in the solar system shows a dense atmosphere?

29. Copyright © 2010 Pearson Education, Inc. Question 8 a) our Moon b) Phobos c) Europa d) Titan e) Triton Which moon in the solar system shows a dense atmosphere? The Huygens probe, deployed by the Cassini spacecraft in 2005, showed that Titan’s atmosphere has a complex organic chemistry.

30. Copyright © 2010 Pearson Education, Inc. Planetary Rings The ring system of Saturn is large and complex, and easily seen from Earth. The other Jovian planets have ring systems as well.

31. Copyright © 2010 Pearson Education, Inc. Which of these moons are most exciting to exobiologists? Question 13 a) Io and Enceladus b) Titan and Europa c) Titan and Triton d) Europa and Miranda e) Phobos and Deimos

32. Copyright © 2010 Pearson Education, Inc. Which of these moons are most exciting to exobiologists? Question 13 a) Io and Enceladus b) Titan and Europa c) Titan and Triton d) Europa and Miranda e) Phobos and Deimos Europa has indications of liquid water beneath the ice. Titan shows evidence of channels under its dense atmosphere.

33. Copyright © 2010 Pearson Education, Inc. Planetary Rings The rings are not solid; they are composed of small rocky and icy particles.

34. Copyright © 2010 Pearson Education, Inc. Planetary Rings Our view of Saturn’s rings changes as the planets move in their orbits.

35. Copyright © 2010 Pearson Education, Inc. Why are the rings of Saturn so bright? Question 7 a) They are made of frozen metallic hydrogen. b) They contain glassy beads expelled by volcanoes on Enceladus. c) They contain shiny bits of iron. d) Titan and other moons reflect additional glow onto the rings. e) They are made of relatively new ice.

36. Copyright © 2010 Pearson Education, Inc. Why are the rings of Saturn so bright? Question 7 a) They are made of frozen metallic hydrogen. b) They contain glassy beads expelled by volcanoes on Enceladus. c) They contain shiny bits of iron. d) Titan and other moons reflect an additional glow onto the rings. e) They are made of relatively new ice. Saturn’s rings are perhaps only 50 million years old, the result of a small moon coming within the planet’s Roche limit.

37. Copyright © 2010 Pearson Education, Inc. Planetary Rings The Roche limit is where the tidal forces of the planet are too strong for a moon to survive; this is where rings are formed.

38. Copyright © 2010 Pearson Education, Inc. The Roche limit is defined as the critical Question 5 a) distance from a planet, inside of which a moon can be tidally destroyed. b) density that a moon can have and be solid. c) distance from a planet that a moon can experience synchronous rotation. d) mass a moon can have and still be classified as a moon.

39. Copyright © 2010 Pearson Education, Inc. The Roche limit is defined as the critical Question 5 a) distance from a planet, inside of which a moon can be tidally destroyed. b) density that a moon can have and be solid. c) distance from a planet that a moon can experience synchronous rotation. d) mass a moon can have and still be classified as a moon. Saturn’s rings, as well as those of the other jovian planets, lie within its planet’s Roche limit.

40. Copyright © 2010 Pearson Education, Inc. Planetary Rings All observed ring systems are within this limit.

41. Copyright © 2010 Pearson Education, Inc. Planetary Rings Voyager probes showed Saturn’s rings to be much more complex than originally thought. Earth is shown on the same scale as the rings. Ring Crossing

42. Copyright © 2010 Pearson Education, Inc. Planetary Rings “Shepherd” moons define the edges of some of the rings.

43. Copyright © 2010 Pearson Education, Inc. Cassini Spacecraft

44. Copyright © 2010 Pearson Education, Inc. Shepherd satellites are defined as Question 6 a) satellites in the coma of a comet. b) moons that confine a narrow ring. c) a type of moon that orbits another moon. d) moons that share an orbit of another, larger moon. e) moons that orbit inside a system of rings.

45. Copyright © 2010 Pearson Education, Inc. Shepherd satellites are defined as Question 6 a) satellites in the coma of a comet. b) moons that confine a narrow ring. c) a type of moon that orbits another moon. d) moons that share an orbit of another, larger moon. e) moons that orbit inside a system of rings.

46. Copyright © 2010 Pearson Education, Inc. Planetary Rings Jupiter has been found to have a small, thin ring.

47. Copyright © 2010 Pearson Education, Inc. How was the ring of Jupiter discovered? Question 4 a) by optical telescopic observers from Earth b) by Voyager I as it passed Jupiter c) by an occultation of a star d) by radar imaging using the Arecibo dish e) with the Hubble Space Telescope’s superior resolution

48. Copyright © 2010 Pearson Education, Inc. How was the ring of Jupiter discovered? Question 4 a) by optical telescopic observers from Earth b) by Voyager I as it passed Jupiter c) by an occultation of a star d) by radar imaging using the Arecibo dish e) with the Hubble Space Telescope’s superior resolution Jupiter’s ring is composed of dark, dusty particles that were first seen when Voyager was past the planet, looking back toward the Sun.

49. Copyright © 2010 Pearson Education, Inc. Planetary Rings The rings of Uranus are more complex.

50. Copyright © 2010 Pearson Education, Inc. Planetary Rings Two shepherd moons keep the epsilon ring from diffusing.

51. Copyright © 2010 Pearson Education, Inc. Planetary Rings Neptune has five rings, three narrow and two wide.

52. Copyright © 2010 Pearson Education, Inc. The rings of Neptune Question 10 a) were confirmed by Voyager 2 in 1989. b) appear both narrow and diffuse. c) all lie within Neptune’s Roche limit. d) often appear as clumpy ring arcs, rather than complete and symmetrical rings. e) All of these are correct.

53. Copyright © 2010 Pearson Education, Inc. The rings of Neptune Question 10 a) were confirmed by Voyager 2 in 1989. b) appear both narrow and diffuse. c) all lie within Neptune’s Roche limit. d) often appear as clumpy ring arcs, rather than complete and symmetrical rings. e) All of these are correct.

54. Copyright © 2010 Pearson Education, Inc. Beyond Neptune Pluto was discovered in 1930. It was thought to be needed to explain irregularities in the orbits of Uranus and Neptune, but it turned out that there were no such irregularities.

55. Copyright © 2010 Pearson Education, Inc. Beyond Neptune Pluto’s moon, Charon, was discovered in 1978. It is orbitally locked to Pluto, and about a sixth as large. Pluto also has two smaller moons, Nix and Hydra, discovered in 2005.

56. Copyright © 2010 Pearson Education, Inc. Question 12 a) a cold terrestrial planet. b) a small jovian planet. c) a large Kuiper belt object. d) a wandering moon. e) a captured comet. Many astronomers believe Pluto is perhaps best classified as

57. Copyright © 2010 Pearson Education, Inc. Many astronomers believe Pluto is perhaps best classified as Question 12 a) a cold terrestrial planet. b) a small jovian planet. c) a large Kuiper belt object. d) a wandering moon. e) a captured comet. Several other large Kuiper belt objects have been discovered, including the largest known, called Eris.

58. Copyright © 2010 Pearson Education, Inc. Beyond Neptune Charon’s orbit is at a large angle to the plane of Pluto’s orbit.

59. Copyright © 2010 Pearson Education, Inc. Astronomy for $100 What is a celestial body that (a)is in orbit around the Sun (b)has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape (c) has cleared the neighborhood around its orbit

60. Copyright © 2010 Pearson Education, Inc. What is a planet?

61. Copyright © 2010 Pearson Education, Inc. Plutoids and the Kuiper Belt The first Kuiper belt objects were observed in the 1990s, and more than 700 are now known. Some of them are comparable in size to Pluto. These images show Eris and its moon Dysnomia.

62. Copyright © 2010 Pearson Education, Inc. Plutoids and the Kuiper Belt This figure shows several of the largest known trans-Neptunian objects, now collectively called plutoids.

63. Copyright © 2010 Pearson Education, Inc. Summary of Chapter 8 Outer solar system has 6 large moons, 12 medium ones, and many smaller ones. Titan has a thick atmosphere and may have flowing rivers of methane. Triton has a fractured surface and a retrograde orbit. Medium-sized moons of Saturn and Uranus are mostly rock and water ice. Saturn’s rings are complex, and some are defined by shepherd moons.

64. Copyright © 2010 Pearson Education, Inc. Summary of Chapter 8, cont. The Roche limit is the closest a moon can survive near a planet; inside this limit rings form instead. Jupiter, Uranus, and Neptune all have faint ring systems. Pluto has three moons, Charon, Nix, and Hydra. Dwarf planets beyond Neptune (including Pluto) are now known as plutoids.