1. Ring World 1

2. Mass EarthSaturn 195.2 (x 10 24 kg) 5.97568 2

3. Size EarthSaturn Radius 1 9.45 Equatorial637860,268 Polar635754,364 Oblateness0.3%9.8% Look for the flattening in the next photo. 3

4. 4 Earth Our Moon

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6. Density EarthSaturn 100%12.5 kg/m 3 5515687 Saturn has the lowest density of all the planets and moons. Saturn would float in water! 6

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8. Large Magnetosphere Saturn’s magnetosphere is about 1/5 th as large as Jupiter’s. –This is expected because Saturn has a thinner conducting mantle of metallic H than Jupiter has. It’s 20x weaker than Jupiter’s field. –It’s actually only 68% as strong as Earth’s! 8

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10. Magnetosphere Jupiter’s magnetosphere is tipped slightly to its rotation, and is complex in structure Saturn’s magnetosphere is aligned almost perfectly with its rotation (axisymmetric), and its structure is very simple. Interesting feature: a ring current. 10

11. Evidence for Saturn’s Magnetic Field! 11

12. Equatorial Ring Current Saturn’s moons Enceladus, Dione, and Tethys are enclosed in a torus of ions (like Jupiter’s Io). This torus is outside the major rings (but inside the thin, tenuous E ring). A current of about 10 million amps flows through this outer ring. 12

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14. Chemical Composition 96.3% H3.25% He (by volume) Traces of methane (CH 4 ), ammonia (NH 3 ), water, ammonium hydrosulfide (NH 4 SH) Like Jupiter, there is a mantle of metallic H under a gaseous H envelope. Rocky / metallic core 14

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16. Saturn’s Orbit Average distance from the sun: 1.43 billion km (9.6 A.U.) Perihelion: 1.35 billion km Aphelion: 1.51 billion km Orbit Eccentricity: 0.056 (slightly more eccentric than Jupiter’s orbit) 16

17. Orbit (2) Orbital Period: 29.5 years –Orbital Velocity: 9.7 km/s Inclination of orbit to ecliptic: 2.5 o 17

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19. Saturn’s Rotation Rotational Period: 10.66 hours (10h 40m) Saturn has zonal winds, like Jupiter, but the colors are more muted. The rotational axis is tilted 26.7 o to the ecliptic. This makes for a periodic tilt in the rings as viewed from the earth. 19

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21. Notice the rotational storm. 21

22. A red oval similar to Jupiter’s GRS. 22

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24. apod.nasa.gov/apod/ap090111.html 24

25. The Rings ! 2 (3) rings visible to the naked eye. –separated by visible gaps. 3 more rings visible telescopically A new ring appears to be forming! 25

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27. Pan orbits within the Encke Division 27

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30. Movie Dusty ring “spokes” 30

31. Rings are Dynamic, not Static Dusty spokes indicate that the rings may be able to change on a short time frame. There are also periodic “ripples” in part of the rings…evidence of a collision between the rings & a comet or asteroid. 31

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33. Braided F ring The ring isn’t really braided, but has spirals around it. 33

34. Here’s a site with more info about the spiral around the F ring. http://www.aim.ufr-physique.univ-paris7.fr/CHARNOZ/homepage/SPIRAL/spiral_uk.htm 34

35. Shepherd Moons Collisions between ring particles should remove kinetic energy from some particles, transfer kinetic energy to others. –Slower particles should fall into Saturn. –Faster particles should leave the ring. –Net: the rings should spread out and dissipate. 35

36. The gravity of the shepherd moons focuses the rings. 36

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38. Barely discernible new ring (with 2 new tiny moons) 38

39. The Larger Moons They’re all ice balls, but they’re not all the same. MimasEnceladusTethys DioneRheaTitan I apetus All of these moons are in synchronous rotation (leading vs. trailing hemisphere differences) 39

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41. Mimas with Herschel Crater Mimas is about the size of Ohio 1150 kg/m 3 41

42. 42 Enceladus

43. 43 Bluish “tiger stripes” South Pole

44. Geysers of water & water vapor erupt from Enceladus’ south pole region. Hot spots have been discovered here by Cassini. 44

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46. Tethys has a gigantic canyon which nearly circles the moon. Ithaca Chasma 46

47. Dione, leading hemisphere at left, trailing at right. 47

48. Dione Direction of movement through space. 48

49. Rhea 49

50. Rhea also has those strange lighter stripes on its trailing hemisphere. 50

51. Titan 5150 km diameter 1880 kg/m 3 Ganymede 5262 km dia. 1940 kg/m 3 How can Titan have a thick atmosphere, when Ganymede doesn’t? Atmosphere of N 2 heavily laden with hydrocarbons: methane ethane Very smoggy 51

52. Titan has a complex layered atmosphere 52

53. Titan’s atmosphere is 95% N 2, 10X denser than Earth’s, and extends 600 km above the surface. 53

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55. Some liquid flows on titan’s surface. 55

56. The shoreline of an ethane lake. 56

57. The darker areas are lakes of liquid methane and ethane. 57

58. At Titan’s surface, the Temperature is about 95K (-290 o F) 58

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60. Iapetus sooty leading hemisphere bright trailing hemisphere equatorial ridge What’s the source of the soot? 60

61. Hyperion – a captured comet? apod.nasa.gov/apod/ap090118.html 61

62. Missions to Saturn Pioneer 11 –Launched 1973, flyby 1979. –Transmitted low-resolution photos of Saturn, rings, moons. Voyager 1 –Launched 1977, flyby 1980 –Transmitted 900+ photos of the moons. –Discovered complexity of rings & nature of Titan’s atmosphere. 62

63. Missions to Saturn (2) Voyager 2 –Launched 1977, flyby 1981 –1150 photographs of the moons Cassini Orbiter with Huygens probe to Titan’s surface. –Launched 1997, arrived in orbit July 1, 2004. 63

64. Cassini’s Mission Cassini is designed to photograph and map Saturn & its moons in visible, infrared, and ultraviolet wavelengths. It has a magnetometer, magnetic imager, and plasma imager to closely study Saturn’s magnetic field. Huygens probe landed on Titan on January 14, 2005. 64

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