JUPITER: KING OF THE PLANETS

JUPITER IS EASILY THE PLANETARY CHAMPION:

  • Mass is 318 times that of Earth = 1.9 x 10^30 g
  • Radius is 71,492 km or 11.21 times Earth's.
  • Density is only 1.33 g/cm^3 or 0.241 of Earth's.

    As seen from Earth:

  • Third brightest object in the night sky.
  • Period of 11.86 years.
  • Semi-major axis of 5.20 AU, e = 0.048.
  • 13 moons discovered from the ground.
  • No solid surface: differential rotation
  • Magnetic (interior) spin period: 9h 55m
  • So fast that ellipticity is over 6.5%

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    JUPITER'S ATMOSPHERE

    Composition

  • Primordial as v_esc = 59.5 km/s
  • 86% H_2 by number; 14% He
  • Small amounts of: CH_4, NH_3, H_2O

    Key Features

    BRIGHT ZONES and DARK BELTS

  • Produced by convection currents:
  • Zones are higher pressure: rising warm
  • Belts are lower pressure: sinking cool
  • Very fast rotation spreads these out E/W
  • Winds up to 400 km/h

    SPOTS and OVALS -- GIANT STORMS

  • Great Red Spot: lasted over 300 years but varies in size
    -- a persistent storm w/ counterclockwise flow
  • White Ovals: over 40 years -- high regions
  • Brown Ovals: holes in clouds -- see depths

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    Vertical Structure of Atmosphere

    NO SOLID SURFACE: Min T (110K) at top of troposphere defines 0 km level

  • There P approx 0.1 P_{oplus}
  • Wien's Law: T = 125K <-- immense internal heat of formation still leaking out
  • Below this, cloud layers:
    Ammonia ice (white)
    Ammonium hydrosulfide (NH_4SH) ice (yellow/brown) -- colorations from Sulfur and S compounds
    Water ice (white/blue)

    Galileo ``lander'' probed atmosphere in 1995

  • penetrated to -150 km
  • 400 K, P approx 30 P_Earth
  • Deep strong winds --> internal heating
  • Ethane (C_2H_6) and phosphine (PH_3) found (some coloring)
    but no organic molecules.

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    JUPITER'S INTERIOR

    All numbers are approximate: from the best theoretical models,
    but no direct data, of course.

    Clouds probably end at -400 km

    MOLECULAR HYDROGEN GAS:

  • 20,000 km thick layer
  • P rises to 3,000,000 atm
  • T increases to 11,000~K

    LIQUID METALLIC HYDROGEN:

  • 40,000 km thick layer
  • P rises to 12,000,000 atm
  • T rises to 25,000 K

    ROCKY/METALLIC CORE:

  • Roughly 10,000 km in radius
  • Central P about 50,000,000 atm
  • Central T about 40,000 K
  • Crushed to about 25 g/cm^3 at center captured asteroid(s); known from Earth
  • 4 more captured moons around 23,000,000 km out: these have retrograde orbits.
  • Many more small moons have been discovered recently by the
    Galileo spacecraft, for a total of 61 known in 2003
    -- all small; most presumably captured asteroids.

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    DETAILS ON THE GALILEAN MOONS

    IO: most active object in SS

    a = 422,000 km; D = 3640 km; M = 1.22 M_{Moon}

    A multicolored surface: yellow, orange, red, brown, and white.

    Thick rocky mantle; Fe/FeS core: rho = 3.5 g/cm^3

    Powerful tidal flexures: P = 1.77d = 1/2 P(Europa)
    ~= 1/4 P(Ganymede) --> forced heating

  • Sulfur volcanos blasting out particles
  • Very smooth, young ( < 1 Myr) surface: new flows
  • Fills up Jupiter's plasma torus with ionized S atoms.

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    EUROPA: Icy & Oceanic?

  • a = 671,000 km
  • D = 3130 km
  • M = 0.65 M_{Moon}
  • rho = 3.04 g/cm^3

  • Icy crust kms thick, temporary cracks
  • Colored areas mostly mineral rich ices
  • Probable 100 km thick ocean -- LIFE EXISTS(ED) THERE ????
  • Surface < 100 Myr old with new ice replacing old
  • Less heating by tidal flexure than Io, but still a good bit

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    GANYMEDE: King of the Moons

  • a = 1,070,000 km
  • D = 5270 km
  • M = 2.02 M_{Moon}

    rho = 1.93 g/cm^3 -- > very thick ice layer

    Rocky mantle, Fe/FeS core

    Many craters, many old ones survive

  • Grooved terrain -- > plate tectonics at 3 Gy
  • Only satellite with a magnetic field