Saturn. Slightly smaller 1/3 the mass density 700 kg/m 3. Interior - light elements, lack of rocky materials. Voyager 2, NASA

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1 Saturn Slightly smaller 1/3 the mass density 700 kg/m 3 Interior - light elements, lack of rocky materials Voyager 2, NASA 1

2 Saturn - Atmosphere belts - driven by rapid rotation period - 10 hrs 14 min storms at intervals of 30 years mostly H, He, some methane, water vapor, ammonia clouds - less colorful than Jupiter, yellow and orange winds 500 m/s near equator 2

3 Saturn - Interior Composition - much like Jupiter maybe a small, rocky core OR no core at all large zone of liquid hydrogen smaller one of metallic liquid hydrogen Saturn emits more energy than it receives from the Sun - leftover from formation 3

4 Moons and Rings Voyager 1, JPL, NASA at least 18 moons densities kg/m 3 Titan: largest Mimas, Enceladus, Tethys, Dione, Rhea, Iapetus moons: mostly ice (60-70%) some rocks (30-40%) 4

5 Titan 50% ice, 50% rock atmosphere - 80% molecular nitrogen (sound familiar?) pressure atm Voyager - orange smog layer, blue at edges => atmosphere varies in composition model: surface covered with a frozen ocean of ethane, methane, nitrogen, below that a layer of acetylene 5

6 Voyager 2, JPL, NASA Enceladus Moons and Rings rotation speeds of rings follow Kepler s Third Law the closer they are to Saturn, the faster they rotate => the rings are made of separate particles 6

7 Ring System ring particles: water ice, rocky particles covered with ice size of golf balls to the size of a house Saturn s crowning glory - the rings 7

8 Uranus Voyager 2, NASA 8

9 Uranus upper atmosphere 58 K mostly molecular H and He bluish green - sunlight scattered by the atmosphere - methane ammonia clouds, banded structure rotation axis almost in plane of orbit density 1300 kg/m 3 9

10 Uranus Composition 15 % H, He 60 % ices - water, methane, ammonia 25% silicates and iron may have a small icy-rock core encased in an icy or watery mantle 10

11 Moons and Rings 5 major moons: Miranda, Ariel, Umbriel, Titania, Oberon surfaces appear to be dirty ice 11

12 Voyager 2, JPL, NASA Miranda: many types of terrain, jumbled together - grooved regions, faults, cliffs strangest surface in the Solar System 12

13 Rings rings discovered accidently rings have low albedo dark carbon material, probably no ice Erich Karkoschka, University of Arizona Lunar & Planetary Lab, NASA magnetic field is tipped 59 o with respect to rotation axis 13

14 Neptune discovered by gravitational effects orbits in 165 years bluish color - methane molecular H and He cloud bands temperature 60 K Voyager Project, NASA 14

15 Neptune - Atmosphere Great Dark Spot storm 30,000 km across region of high pressure bright, cirrus-like clouds, condensed methane no complex swirls seen magnetic field - tilted 47 o from rotation axis 15

16 Moons and Rings Triton largest retrograde orbit tidally locked very thin atmosphere, mostly nitrogen with trace methane APOD 16

17 Triton not too heavily cratered surface relatively young, recently modified temperature 37 K atmosphere - mostly nitrogen, trace of methane erupting geyser! 2100 kg/m 3 => rocky core surrounded by a mantle of methane and water ice 17

18 Pluto and Charon discovered by tedious searching of photographic plates 39 AU from the Sun, now is orbiting closer than Neptune methane coated ice surface temperature 60 K nitrogen and CO ices rotation period 6.4 days atmosphere - N, CO, methane 18

19 Charon - Moon or Double Planet? smaller than Pluto km diameter, Pluto 2300 km synchronous rotation can use Charon to calculate the mass of Pluto ( now how do you do that?) average density together is 2000 kg/m 3 Pluto is 75% rocky materials 19

20 Charon water frost on surface, could be icy materials totally could these be moons of Neptune s that escaped? 20