Comparative Planetology of the Outer Planets. A Travel Guide to the Outer Planets. Chapter 18 (150+ slides) Jupiter

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1 Comparative Planetology of the Outer Planets A Travel Guide to the Outer Planets Chapter 18 (150+ slides) Hydrogen-rich atmospheres belt-zone circulation interiors mostly liquid hydrogen shallow atmospheres Large satellite systems

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4 Physical Properties of Equatorial Radius: 71,494 km times the earth s radius Mass times the earth s mass Distance from Sun AU Orbital Period years

5 Planet Mass (Earth) Mercury Venus Earth Mars Uranus Neptune Pluto The scale of the Solar System Object Distance (million km) AU Light Minute Light Hour Light Day Light Year Mercury Venus Earth Mars Ceres (asteroid) , Uranus 2, Neptune 4, Pluto 5, Farthest comets 14,958,302 99, ,017 13, Proxima Centauri (nearest star) 41,041, ,340 2,280,070 38,001 1,583 4 Orion Nebula 14,200,920,000 94,672, ,940,000 13,149, ,875 1,500 Center of the Milky Way Andromeda Galaxy (farthest naked-eye object) 246,149,280,000 1,640,995, ,342,780,800,000, ,951,872,000, ,674,960,0 00 1,241,265,600,000, ,916,000 9,496,500 26,000 20,687,760,000, ,990,000,000 2,360,000,000 Largest and most massive planet in the solar system: s Interior From radius and mass Average density of 1.34 g/cm 3 => can not be made mostly of rock, like earthlike planets. consists mostly of hydrogen and helium. Contains almost 3/4 of all planetary matter in the solar system. Visual image Infrared falsecolor image Most striking features visible from Earth: Multi-colored cloud belts Due to the high pressure, hydrogen is compressed into a liquid, and even metallic state.

6 Aurorae on Just like on Earth, s magnetosphere produces aurorae concentrated in rings around the magnetic poles. ~ 1000 times more powerful than aurorae on Earth. s Magnetic Field Discovered through observations of decimeter (radio) radiation Magnetic field at least 10 times stronger than Earth s magnetic field. Magnetosphere over 100 times larger than Earth s magnetosphere. Extremely intense radiation belts: Very high energy particles can be trapped; radiation doses corresponding to ~ 100 times lethal doses for humans! Comet Impact on s Atmosphere Impact of 21 fragments of comet Shoemaker- Levy 9 in 1994 Visual: Impacts seen for many days as dark spots Impacts occurred just behind the horizon as seen from Earth, but came into view about 15 min. later. Impact sites appeared very bright in the infrared. Impacts released energies equivalent to a few megatons of TNT (Hiroshima bomb: ~ 0.15 megaton)! s liquid hydrogen ocean has no surface: Gradual transition from gaseous to liquid phases as temperature and pressure combine to exceed the critical point. shows limb darkening hydrogen atmosphere above cloud layers. Only very thin atmosphere above cloud layers; transition to liquid hydrogen zone ~ 1000 km below clouds.

7 Clouds in s Atmosphere (II) Three layers of clouds: 1. Ammonia (NH 3 ) crystals The Cloud Belts of Dark belts and bright zones. Zones higher and cooler than belts; high-pressure regions of rising gas. 2. Ammonia hydrosulfide (NH 4 SH) 3. Water crystals The Cloud Belts on (II) Just like on Earth, high-and low-pressure zones are bounded by high-pressure winds. s cloud belt structure has remained unchanged since humans began mapping them. Coriolis

8 Galileo spacecraft image of s ring, illuminated from behind s Ring Not only, but all four gas giants have rings. s ring: dark and reddish; only discovered by Voyager 1 spacecraft. Composed of microscopic particles of rocky material Location: Inside Roche limit, where larger bodies (moons) would be destroyed by tidal forces. Rings must be constantly re-supplied with new dust. Ring material can t be old because radiation pressure and s magnetic field force dust particles to spiral down into the planet. Uranus Rings made of Dust Rings made of Dust Neptune Rings made of Ice Rings made of Dust

9 s Moons s Moons 1. Io 2. Europa 3. Ganymede 4. Callisto 5. Amalthea Io 6. Himalia 7. Elara Europa 8. Pasiphae 9. Sinope 10. Lysithea Callisto 11. Carme 12. Ananke 13. Leda Ganymede 14. Thebe 15. Adrastea 16. Metis 17. Callirrhoe 18. Themisto 19. Megaclite 20. Taygete 21. Chaldene 22. Harpalyke 23. Kalyke 24. Iocaste 25. Erinome 26. Isonoe 27. Praxidike 28. Autonoe 29. Thyone 30. Hermippe 31. Aitne 32. Eurydome 33. Euanthe 34. Euporie 35. Orthosie 36. Sponde 37. Kale 38. Pasithee 39. Hegemone 40. Mneme 41. Aoede 42. Thelxinoe 43. Arche 44. Kallichore 45. Helike 46. Carpo 47. Eukelade 48. Cyllene 49. Kore 50. Herse 1. S/2003 J2 2. S/2003 J3 3. S/2003 J4 4. S/2003 J5 5. S/2003 J9 6. S/2003 J10 7. S/2003 J12 8. S/2003 J15 9. S/2003 J S/2003 J S/2003 J S/2003 J S/2010 J S/2010 J 2 and two moons 50 moons & 14 provisional moons are known of for Four largest moons discovered by Galileo are know as The Galilean Moons Io Europa Ganymede Callisto

10 Callisto: The Ancient Face Callisto Tidally locked to, like all of s moons. Av. density: 1.79 g/cm3 composition: mixture of ice and rocks Dark surface, heavily pocked with craters. No metallic core: Callisto never differentiated to form core and mantle. No magnetic field. Layer of liquid water, ~ 10 km thick, ~ 100 km below surface, probably heated by radioactive decay. Ganymede: A Hidden Past Largest of the 4 Galilean moons. Av. density = 1.9 g/cm3 Rocky core Ice-rich mantle Crust of ice 1/3 of surface old, dark, cratered; rest: bright, young, grooved terrain Callisto is surrounded by an extremely thin atmosphere composed of carbon dioxide and probably molecular oxygen. Investigation revealed that Callisto may possibly have a subsurface ocean of liquid water at depths less than 300 kilometers. The likely presence of an ocean within Callisto indicates that it can or could harbor life. However, this is less likely than on nearby Europa. Callisto has long been considered the most suitable place for a human base for future exploration of the system since it is furthest from the intense radiation of. Bright terrain probably formed through flooding when surface broke

11 Ganymede Europa: A Hidden Ocean The Surface of Europa Av. density: 3 g/cm 3 composition: mostly rock and metal; icy surface. Close to should be hit by many meteoroid impacts; but few craters visible. Active surface; impact craters rapidly erased. Cracked surface and high albedo (reflectivity) provide further evidence for geological activity.

12 The Interior of Europa Europa is too small to retain its internal heat Heating mostly from tidal interaction with. Core not molten No magnetic field. Europa Europa has a liquid water ocean ~ 15 km below the icy surface. Ganymede is composed of approximately equal amounts of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core, and an internal ocean that may contain more water than all of Earth's oceans combined. Its surface is composed of two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of the satellite. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's disrupted geology is not fully known, but was likely the result of tectonic activity due to tidal heating.

13 Io: Bursting Energy - Io Most active of all Galilean moons; no impact craters visible at all. Over 100 active volcanoes! Activity powered by tidal interactions with. Av. density = 3.55 g/cm 3 Interior is mostly rock. Io's volcanism is responsible for many of its unique features. Its volcanic plumes and lava flows produce large surface changes and paint the surface in various subtle shades of yellow, red, white, black, and green, largely due to allotropes and compounds of sulfur.

14 With over 400 active volcanoes, Io is the most geologically active object in the Solar System. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Io's silicate crust. Io is primarily composed of silicate rock surrounding a molten iron or iron-sulfide core. Most of Io's surface is composed of extensive plains coated with sulfur and sulfur-dioxide frost.

15 Formed from cold gas in the outer solar nebula, where ices were able to condense. Rapid growth Soon able to trap gas directly through gravity Heavy materials sink to the center The History of In the interior, hydrogen becomes metallic (very good electrical conductor) Rapid rotation strong magnetic field Rapid rotation and large size belt-zone cloud pattern Dust from meteorite impacts onto inner moons trapped to form ring Moons (For Test Including Terrestrial Planets) Deimos (Mars) Io () Europa () Callisto () Ganymede () Moon (Earth) Phobos (Mars)

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17 Physical Properties of Mass: ~ 1/3 of mass of Radius: ~ 16% smaller than Equatorial Radius: 60,330 km 94.2 times Earth s radius 0.84 times s radius Mass times Earth s mass times s mass Distance from Sun AU ( is 5.2 AU) Orbital Period years ( is years) Av. density: 0.69 g/cm 3 Would float in water! Rotates about as fast as, but is twice as oblate No large core of heavy elements. Mostly hydrogen and helium; liquid hydrogen core. radiates ~ 1.8 times the energy received from the sun. Probably heated by liquid helium droplets falling towards center. s Atmosphere Three-layered cloud structure, just like on Main difference to : Fewer wind zones, but much stronger winds than on : Winds up to ~ 500 m/s near the equator!

18 s Rings Ring consists of 3 main segments: A, B, and C Ring separated by empty regions: divisions Rings can t have been formed together with because material would have been blown away by particle stream from hot at time of formation. A Ring B Ring C Ring Cassini Division Rings must be replenished by fragments of passing comets / meteoroids. The full set of rings, as photographed by the Cassini spacecraft on September 15, 2006 (brightness has been exaggerated in this image).

19 Composition of s Rings Rings are composed of ice particles moving at large velocities around, but small relative velocities (all moving in the same direction). s Moons s Moons Titan 1. Mimas 2. Enceladus 3. Tethys 4. Dione 5. Rhea 6. Titan 7. Hyperion 8. Iapetus 9. Erriapus 10. Phoebe 11. Janus 12. Epimetheus 13. Helene 14. Telesto 15. Calypso 16. Kiviuq 17. Atlas 18. Prometheus 19. Pandora 20. Pan 21. Ymir 22. Paaliaq 23. Tarvos 24. Ijiraq 25. Suttungr 26. Mundilfari 27. Albiorix 28. Skathi 29. Siarnaq 30. Thrymr 31. Narvi 32. Methone 33. Pallene 34. Polydeuces 35. Daphnis 36. Aegir 37. Bebhionn 38. Bergelmir 39. Bestla 40. Farbauti 41. Fenrir 42. Fornjot 43. Hati 44. Hyrrokkin 45. Kari 46. Loge 47. Skoll 48. Surtur 49. Greip 50. Jarnsaxa 51. Tarqeq 52. Anthe 53. Aegaeon 1. S/2004 S7 2. S/2004 S12 3. S/2004 S13 4. S/2004 S17 5. S/2006 S1 6. S/2006 S3 7. S/2007 S2 8. S/2007 S3 9. S/2009 S1

20 A Shepherd, his Staff and the Sheep Shepherd Moons Some moons on orbits close to the rings focus the ring material, keeping the rings confined. Shepherd Moons () Divisions and Resonances Moons do not only serve as shepherds. Where the orbital period of a moon is a small-number fractional multiple (e.g., 2:3) of the orbital period of material in the disk ( resonance ), the material is cleared out Divisions

21 Electromagnetic Phenomena in s Rings Titan: s Largest Moon Radial spokes in the rings rotate with the rotation period of : Magnetized ring particles lifted out of the ring plane and rotating along with the magnetic-field structure About the size of s moon Ganymede. Rocky core, but also large amount of ice. Thick atmosphere, hiding the surface from direct view. Titan s Atmosphere Liquid Methane on the surface of Titan Because of the thick, hazy atmosphere, surface features are only visible in infrared images. Many of the organic compounds in Titan s atmosphere may have been precursors of life on Earth. Surface pressure: 50% greater than air pressure on Earth Surface temperature: 94 K (-290 o F) Methane and ethane are liquid! Methane is gradually converted to ethane in the Atmosphere Methane must be constantly replenished, probably through breakdown of ammonia (NH 3 ).

22 s Smaller Moons s smaller moons formed of rock and ice. s Smaller Moons s smaller moons formed of rock and ice. Tethys: Heavily cratered; marked by 3 km deep, 1500 km long crack. Iapetus: Two-toned moon with larger crater

23 s Smaller Moons s smaller moons formed of rock and ice. Moons (For Test Including Terrestrial Planets) Enceladus: Possibly active; regions with fewer craters, containing parallel grooves, believed to be filled with frozen water. Deimos (Mars) Titan () Io () Europa () Callisto () Ganymede () Moon (Earth) Phobos (Mars) Uranus What The you way expect it is

24 Orbit slightly elliptical; orbital period 84 years. Very unusual orientation of rotation axis: Almost in the orbital plane. Possibly result of impact of a large planetesimal during the phase of planet formation. Large portions of the planet exposed to eternal sunlight for many years, then complete darkness for many years! The Motion of Uranus AU 97.9 o Physical Properties of Uranus Equatorial Radius: 25,559 km 4.01 times Earth s radius 0.36 times s radius Mass times Earth s mass times s mass Distance from Sun AU ( is 5.2 AU) Orbital Period years ( is years) 1/3 the diameter of 1/20 the mass of no liquid metallic hydrogen Deep hydrogen + helium atmosphere Uranus The Atmosphere of Uranus Like other gas giants: No surface. Gradual transition from gas phase to fluid interior. Mostly H; 15% He, a few % methane, ammonia and water vapor. Optical view from Earth: Blue color due to methane, absorbing longer wavelengths Cloud structures only visible after artificial computer enhancement of optical images taken from Voyager spacecraft.

25 Cloud Structures of Uranus Hubble Space Telescope image of Uranus shows cloud structures not present during Voyager s passage in Possibly due to seasonal changes of the cloud structures. The Rings of Uranus Rings of Uranus and Neptune are similar to s rings. Confined by shepherd moons; consist of dark material. Apparent motion of star behind Uranus and rings Rings of Uranus were discovered through occultations of a background star

26 Uranus Uranus Moons Uranus Uranus Moons Oberon Titania Umbriel Ariel Miranda 1. Cordelia 2. Ophelia 3. Bianca 4. Cressida 5. Desdemona 6. Juliet 7. Portia 8. Rosalind 9. Mab 10. Belinda 11. Perdita 12. Puck 13. Cupid 14. Miranda 15. Francisco 16. Ariel 17. Umbriel 18. Titania 19. Oberon 20. Caliban 21. Stephano 22. Trinculo 23. Sycorax 24. Margaret 25. Prospero 26. Setebos 27. Ferdinand The Moons of Uranus 5 largest moons visible from Earth. 10 more discovered by Voyager 2; more are still being found. Uranus s Moons Moon Location Size %Moon Oberon outermost 775km 44% Dark surfaces, probably ice darkened by dust from meteorite impacts. 5 largest moons all tidally locked to Uranus.

27 Uranus s Moons Moon Location Size %Moon Titania 805km 44% Uranus s Moons Moon Location Size %Moon Umbriel 595km 35% Uranus s Moons Moon Location Size %Moon Ariel 580km 35% Uranus s Moons Moon Location Size %Moon Miranda innermost 242km 14%

28 Uranus s Moons Moons (For Test Including Terrestrial Planets) Moon Location Size %Moon Oberon outermost 775km 44% Titania 805km 44% Umbriel 595km 35% Ariel 580km 35% Miranda innermost 242km 14% They all have active surfaces Oberon (Uranus) Titania (Uranus) Umbriel (Uranus) Ariel (Uranus) Deimos (Mars) Miranda (Uranus) Titan () Io () Europa () Callisto () Ganymede () Moon (Earth) Phobos (Mars) Neptune

29 Physical Properties of Neptune Equatorial Radius: km 39.3 times Earth s radius 0.35 times s radius Mass times Earth s mass times s mass Distance from Sun 30.1 AU ( is 5.2 AU) Orbital Period years ( is years) Made of dark material, visible in forwardscattered light. Ring material must be regularly re-supplied by dust from meteorite impacts on the moons. The Rings of Neptune Focused by small shepherd moons embedded in the ring structure. Interrupted between denser segments (arcs) Neptune Discovered in 1846 at position predicted from gravitational disturbances on Uranus orbit by J. C. Adams and U. J. Leverrier. Blue-green color from methane in the atmosphere 4 times Earth s diameter; 4 % smaller than Uranus

30 The Atmosphere of Neptune Neptune Triton Nereid Neptune s Moons 1. Naiad 2. Thalassa 3. Despina 4. Galatea 5. Larissa 6. Proteus 7. Triton 8. Nereid 9. Psamathe Cloud-belt structure with high-velocity winds; origin not well understood. Darker cyclonic disturbances, similar to Great Red Spot on, but not long-lived. White cloud features of methane ice crystals 1. S/2002 N 1 2. S/2002 N 2 3. S/2002 N 3 4. S/2002 N 4 The Moons of Neptune Two moons (Triton and Nereid) visible from Earth; 6 more discovered by Voyager 2 Unusual orbits: Triton: Only satellite in the solar system orbiting clockwise, i.e. backward. Nereid: Highly eccentric orbit; very long orbital period (359.4 d). Neptune The Surface of Triton Very low temperature (34.5 K) Triton can hold a tenuous atmosphere of nitrogen and some methane; 10 5 times less dense than Earth s atmosphere. Surface composed of ices: nitrogen, methane, carbon monoxide, carbon dioxide. Possibly cyclic nitrogen ice deposition and re-vaporizing on Triton s south pole, similar to CO 2 ice polar cap cycles on Mars. Dark smudges on the nitrogen ice surface, probably due to methane rising from below surface, forming carbon-rich deposits when exposed to sunlight.

31 Neptune The Surface of Triton (II) Ongoing surface activity: Surface features probably not more than 100 million years old. Large basins might have been flooded multiple times by liquids from the interior. Ice equivalent of greenhouse effect may be one of the heat sources for Triton s geological activity. Triton (Neptune) Nereid (Neptune) Oberon (Uranus) Titania (Uranus) Umbriel (Uranus) Ariel (Uranus) Deimos (Mars) Moons (For Test Including Terrestrial Planets) Miranda (Uranus) Titan () Io () Europa () Callisto () Ganymede () Moon (Earth) Phobos (Mars) The Jovian Planets Uranus Neptune Name Distance from sun (AU) Size (km) 3 1 Ceres TY KX XV VS TC QF Orcus AZ Pluto Ixion Huya RN SM MS SB GV UX Varuna TX TO OP EL Quaoar QW CD CS CN WH FY PR MW CY KW AW WC QX FY UR TC DE XR YW Eris RM Sedna

32 Physical Properties of Pluto Equatorial Radius: 1185 km 0.18 times Earth s radius 0.02 times s radius Mass times Earth s mass times s mass Distance from Sun AU ( is 5.2 AU) Rotation Period years ( is years) Pluto is NOT a Planet Virtually no surface features visible from Earth. ~ 65 % of size of Earth s Moon. Highly elliptical orbit; coming occasionally closer to the sun than Neptune. Orbit highly inclined (17 o ) against other planets orbits Neptune and Pluto will never collide. Surface covered with nitrogen ice; traces of frozen methane and carbon monoxide. Daytime temperature (50 K) enough to vaporize some N and CO to form a very tenuous atmosphere.

33 Definition of a Planet Pluto s Moon Charon Planets: The eight worlds starting with Mercury and moving out to Venus, Earth, Mars,,, Uranus and Neptune. Dwarf planets: Pluto and any other round object that "has not cleared the neighborhood around its orbit, and is not a satellite." Small solar system bodies: All other objects orbiting the sun. Discovered in 1978; about half the size and 1/12 the mass of Pluto itself. Tidally locked to Pluto. Hubble Space Telescope image

34 Pluto and Charon Orbit highly inclined against orbital plane. From separation and orbital period: M pluto ~ 0.2 Earth masses. The Origin of Pluto and Charon Probably very different history than neighboring Jovian planets. Older theory: Pluto and Charon formed as moons of Neptune, ejected by interaction with massive planetesimal. Mostly abandoned today since such interactions are unlikely. Density 2 g/cm 3 (both Pluto and Charon) ~ 35% ice and 65% rock. Large orbital inclinations Large seasonal changes on Pluto and Charon. Modern theory: Pluto and Charon members of Kuiper belt of small, icy objects. Collision between Pluto and Charon may have caused the peculiar orbital patterns and large inclination of Pluto s rotation axis. Moons (For Test Including Terrestrial Planets) Triton (Neptune) Nereid (Neptune) Oberon (Uranus) Titania (Uranus) Umbriel (Uranus) Ariel (Uranus) Deimos (Mars) Miranda (Uranus) Titan () Io () Europa () Callisto () Ganymede () Moon (Earth) Phobos (Mars)

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36 October 7, 2002 NASA's Hubble Space Telescope has measured the largest object discovered in the solar system since the discovery of Pluto 72 years ago. Approximately half the size of Pluto, the icy world 2002 LM60, dubbed "Quaoar" (pronounced kwa-whar) by its discoverers, is the farthest object in the solar system ever to be resolved by a telescope. It was initially detected by a groundbased telescope, as simply a dot of light, until astronomers aimed the powerful Hubble telescope at it. Sedna This artist's concept shows the planet catalogued as 2003UB313 at the lonely outer fringes of our solar system. Our Sun can be seen in the distance. The new planet, which is yet to be formally named, is at least as big as Pluto and about three times farther away from the Sun than Pluto. It is very cold and dark. The planet was discovered by the Samuel Oschin Telescope at the Palomar Observatory near San Diego, Calif., on Jan. 8, Image credit: NASA/JPL-Caltech

37 Triton (Neptune) Nereid (Neptune) Oberon (Uranus) Titania (Uranus) Umbriel (Uranus) Ariel (Uranus) Deimos (Mars) Moons (For Test Including Terrestrial Planets) Miranda (Uranus) Titan () Io () Europa () Callisto () Ganymede () Moon (Earth) Phobos (Mars) Don t forget In Class Test next week!!!