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Jupiter and the Jovian Planets

Jupiter and the Jovian Planets. Formation of Jovian Planets. Step 1  Accretion of planetesimals to form large Earth-like solid planet cores of rocks, iron, nickel Masses of Cores in terms of Earth ’ s mass Jupiter - 28 Saturn - 17

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Jupiter and the Jovian Planets

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  1. Jupiter and the Jovian Planets

  2. Formation of Jovian Planets • Step 1 Accretion of planetesimals to form large Earth-like solid planet cores of rocks, iron, nickel • Masses of Cores in terms of Earth’s mass Jupiter - 28 Saturn - 17 Uranus - 3.5 Neptune - 4.3 • Step 2  Lighter gases condense on to the planet cores due to gravity and cold temperatures

  3. Jupiter – Formation of Planetary Systems

  4. Jupiter – “A Failed Star” • Jupiter is 318 times more massive than the Earth; yet, it is 80 times too small to become a star, i.e. make nuclear energy from fusion like the Sun • But Jupiter (and Saturn) emits roughly twice the energy it receives from the Sun • Energy derives from self-gravity  gravitational compression of the interior (Jupiter shrinks about an inch per century) • Surface T = 124 K, but expected 109 K (assuming Sun to be the only source) • Jupiter radiates (124 / 109)4 = 1.7 times more energy than would be expected

  5. “Ice” Rock Jupiter Interior Molecular Hydrogen Metallic Hydrogen

  6. Conditions inside Jupiter • Composition like the Sun: mostly H, He • Atmosphere 500 miles thick, largely H2, He, and CH4, NH3, H2O • Very low mean density of 1.33 g/cc (including compressed core)  planet must be largely liquid • “Surface” is largely top of liquid hydrogen ocean (Jovian planets have no solid surface), where “Air pressure” is 500 x Earth’s, and temperature of 4000 F • Equator and poles do not rotate at same rate (oblate shape): 9h 50min and 9h 55 min respectively • Huge magnetic field, why?

  7. Jupiter’s Interior • Most of Jupiter is about 40,000 mile deep ocean of liquid hydrogen • But it is mostly metallic H2: high density and pressure compress the H2 molecule so that they “share” electrons, i.e. electrons can move around like in a metal  conduct electricity • “Core” is solid ice, rock, iron, nickel at very high pressure (1 billion lbs / sq. inch) - core itself is about 28 x Earth’s mass - temperature 50,000 F

  8. Rock Saturn Interior Molecular Hydrogen Metallic Hydrogen “Ice”

  9. Interiors of Jupiter and Saturn

  10. Molecular Hydrogen Rocky Cores Slushy “Ice”Mantles Uranus Neptune Interiors of Uranus & Neptune

  11. Earth Jupiter Saturn Metallic Hydrogen Neptune Uranus Jupiter and Saturn have metallic hydrogen mantle; Uranus and Neptune don’t

  12. Temperature (pressure) in Jupiter rises faster than in Saturn with depth Although T and P are high in the cores, not sufficient for nuclear fusion like stars Require millions of degrees!

  13. Jupiter – The King of Planets Stripes, What are they?

  14. The Red Spot – What is it? First seen by Galileo, over 350 years ago ! Twice the size of the Earth

  15. A long lasting (over 300 years!!), internally powered, cyclonic storm (but what sustains it?)

  16. Rapid rotation of Jupiter Period ~ 10 hrs  In spite of its size (318 times more massive than the Earth) it rotates 2 ½ times faster. But there is very little tilt of rotation axis (3 degrees)  No Seasons !

  17. Internal energy source Strong convection currents What provides the internal energy source ? Self-gravity!

  18. Jupiter – Vital Statistics • Equatorial radius = 71,500 Kms • Orbital period = 11.86 Earth years • Mean density = 1.33 g/cc (3.5 times lower than Earth’s) • Indicates mostly H2 interior, but at tremendous pressure  Metallic Hydrogen (conducts electricity!), up to about 20,000 Kms into the center • Alternating lighter and darker stripes on the surface are zones of rising (warmer) and falling (cooler) material

  19. Vertical Convection: “Belts” and “Zones” Cloud patterns are at different temperatures (altitudes) and wind speeds; tremendous “wind shear” (reverse direction at different altitudes)

  20. Jovian Interior Mostly metallic hydrogen  electrically conducting interior  huge magnetic field

  21. Jovian Magnetosphere Note that scale on bottom right! Jupiter’s magnetic field is 20,000 times stronger than Earth’s

  22. Jupiter’s Magnetic Field • 20,000 times stronger than Earth’s, due to convection in liquid metallic H2 interior; convection is due to rapid rotation • “Fast electrons” produced when the solar wind hits Jupiter’s magnetosphere • Lethal rays: density of particles is thousands of times fatal human dosage • Magnetosphere extends up to Saturn, 5 AU away

  23. Jupiter and the 4 Galilean Moons:Io, Europa, Ganymede, Callisto

  24. Relative sizes of Galilean Moons

  25. Galilean Moons: Io, Europa, Ganymede, Callisto Rocky to Icy (Ganymede is the largest moon in the solar system) Io and Europa are mostly rocky but Ganymede and Callisto have more ices; Densities: 3.6, 3.0, 1.9, 1.8 g/cc respectively.

  26. Jovian Moons • In addition to the 4 Galilean satellites, 12 other moons of Jupiter have been discovered • Owing to Jupiter’s tidal effects all Galilean moons are ‘synchronous rotators’: they keep the same face towards Jupiter • Voyager also found a ring around Jupiter, in between two small moons before Io • Latest NASA probe of Jupiter is called Galileo

  27. IO • Closest large moon to Jupiter • Orbital period = 42 hrs • Surface has no impact craters, so less than 1 million years old • Many volcanic craters – active volcanoes • No water (too hot), but lots of sulfur on surface (sulfur condenses easily; appears black when heated)

  28. Erupting volcanoes (taped live!)

  29. Hot-spots at volcanoes

  30. Io’s Volcanic Activity • Eight volcanoes seen by Voyager (many more seen since) • Plumes rise 100 miles, spread over hundreds of miles • Surface temp roughly 700 F near volcanoes, -250 F away from them • Caused by Jupiter’s tidal effect  large land tides, up to 100 yards in height • Friction inside Io produces heat and volcanic activity (“squeezed” like a ketchup bottle !)

  31. Pizza?

  32. Volcanic features on Io

  33. Typical volcanic feature on Io

  34. Io’s orbit around Jupiter:Sulfur emission (spectral lines)

  35. Io and Jupiter’s Magnetic Field • Magnetic field rotates with the planet, and electrifies the orbit of IO  plasma (charged particles) torus surrounding orbit of IO; contains Sulfur ions S+ (emission spectral lines detected on the Earth)

  36. Electrically charged atmosphere surrounding Jupiter and orbit of Io

  37. Radio emission from around Jupiter • “Synchrotron radiation” at radio wavelengths is produced by “fast electrons” • from the magnetosphere • Jupiter’s radio signals are detected on the earth! Interfere with radio • Communications with CB, short-wave radio, radar, UHF TV, etc.

  38. Europa: Ice rafts moving on liquid water oceans Very thin Oxygen atmosphere has been detected on Europa

  39. Comparison of Jovian Moons: Evolution due to Jupiter’s gravity Resolution Rocky  Icy

  40. Sizes and Distances of Galilean Satellites Sizes relative to Earth’s Moon ( = 1): 1.1, 0.9, 1.5, 1.4 respectively

  41. Many moons of Jupiter

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