The Outer Planets

1. The Outer Planets

2. Cosmic Abundance of Elements

3. Major Constituents

4. Interiors: Big H2 Atmospheres

5. Jupiter vs Saturn

6. Jupiter’s Ammonia Clouds: Belts: Dark bands Zones: Bright bands Great Red Spot White Ovals The GRS has lived at least 300 yrs. Ovals have been seen to survive tens of years

7. Jupiter’s clouds result from convection. • Hot air expands. • Lighter than the rest of the air, it rises. • As it rises, it cools and condenses forming clouds. • When it is cooler than the ambient air, it sinks.

8. Great Red Spot

9. Saturn’s Clouds

10. Uranus Absorption of sunlight at red wavelengths by methane renders the planet blue.

11. Neptune Neptune emits more energy from its interior than does Uranus. This energy drives weather. The colder temperatures cause methane to condense in the upper atmosphere – these are the clouds that we see.

12. Jupiter’s Rings Silicate dust, 10,000 times more transparent than window glass.

13. Moons Their densities tell us that they are 1/2 rock & 1/2 ice. A typical, heavily cratered, terrain. Saturn’s moon, Tethys

14. Jupiter’s Moons

15. Europa Few craters A terrain containing elements that were recently dislodged can be seen to neatly fit together if rotated and translated in position.

16. Io Io • Images\iovol_vgr.gif

17. What fuels Io? Each time Ganymede orbits once, Europa orbits twice, and Io orbits 4 times.

18. Plumes fountain 500 km above the Surface

19. Io’s surface is almost devoid of craters, for it is being repaved at a rapid rate. The glow of warm lava. A pool of lava (black) covered with sulfur deposits (orange). This is called Tupan Patera after the Brazilian thunder god. Images taken from the Galileo spacecraft.

20. Io is hot Lava flows on Io exceed 1500 K in temperature. Lavas this hot are not sulfur (which would evaporate immediately). This is hotter than present lavas on Earth (1300-1450 K). Instead these lavas are likely ultramafic (rich in Mg and Fe), similar to the lavas that occurred on early Earth. Present hypothesis, a ~100 km thick crust floats on top of a worldwide ocean of magma 800 km deep.

21. Neptune’s Largest Moon: Triton Triton On Triton the main component of the atmosphere, nitrogen, exits in vapor pressure equilibrium. That is, it exists as an ice on the surface and as vapor in the atmosphere, in the same way that water exists as liquid and ice on Earth’s surface and as a gas in the atmosphere. The amount of gas depends on the temperature. Less exists at cooler temperatures. This is seen on Earth with the condensation of water at dew point. Atmosphere: 1.6x10-7 bar 38K Nitrogen

22. Summary • Giant planets are large gas planets with nearly solar elemental abundances. • They have small ice-rock cores. • Their moons are ½ rock and ½ ice. • Most moons display heavily cratered terrains. Io, Europa, Triton and Titan are exceptions. • All jovian planets sport rings of differing thicknesses, compositions & character. • Titan supports an atmosphere second only to Venus’ (considering bodies with proper surfaces). It is rich with organics, and its origin is unknown. • The Cassini mission to the saturnian system is in route and functioning well.

23. Titan: a moon with an atmosphere

24. Saturn’s largest moon compared to Jupiter’s largest moons Ganymede Size: 4800 Mass: 1.5x1023 Titan Size:5150 km Mass: 1.3x1023 Callisto Size: 5268 Mass: 1.1x1023

25. Observações da alta atmosfera

26. Composition of Titan’s stratosphere MoleculeAbundance N2 65-98% CH4 2-10% H2 0.2-0.6% CO 6-150 ppm CH3D 5-180 ppm C2H6 13-20 ppm C2H2 2-5 ppm C3H8 0.5-4 ppm C2H4 0.09-3 ppm HCN 0.2-2 ppm HC3N 80-250 ppb CH3C2H 4-60 ppb C4H2 1-40 ppb C2N2 5-16 ppb CO2 1.5-14 ppb Derived from radiative transfer analyses of Voyager, ISO and ground-based data.

27. Oceans? hν H2 CH4  + CH4 -> other hydrocarbons Methane in atmosphere is depleted in107 years. Either methane is supplied or we are witnessing Titan at a particular moment in its history. Oceans containing methane explain the near saturated tropospheric conditions, provide a source for methane, and don’t require a penchant for being lucky. Flasar et al. Science221, 55 Lunine et al. Science222, 1229 haze C2H2 C2H6 Ocean (CH4, C2H6, N2)

28. Production Rate * Depth assuming global coverage & 4.5 Gyr of production Taken from Lunine et al. 1989. Based on Yung et al. 1984, Raulin (1984)

29. Expected Surface ScenarioSagan & Dermott 1982

31. Titan’s Surface HST images Peter Smith et al. U. of Arizona

34. Testing Cassini (Jet Propulsion Laboratory, California) We can see the main antenna. All the instruments (e.g. the cameras) are covered.

35. Huygens Probe, European Space Agency We can see the shield that protects the instruments against the heat of entry into the atmosphere.

36. In 2005, the desent of Huygen’s into Titan’s atmosphere. At 170 km altitude, Huygens releases the shield and begins measurements.

37. 15 October 1997 Cassini-Huygens spacecraft, on a Titan IV rocket, waiting for takeoff.

38. A perfect takeoff that saved fuel.

39. ISS Images

40. Huygens DIRS Descent Movie Ice Mountains  Landing Site View of Landing Site

41. Huygen’s DISR ImagesPI: Marty TomaskoUniversity of Arizona Foreground stones are 6 inches

42. More DISR Images. DISR

43. Washes flow downhill Tomasko et al. Nature 438, 765

44. Huygens aterrizou ~30km ao sul das dunas  Sitio de aterrissagem Imagem do Cassini Radar (no modulo orbital) Larry Soderblom