JOVIAN (GAS GIANT) PLANETS

JUPITER: King of the Planets It’s got more than twice the right stuff (mass, that is) than all the other planets put together! Viewed from distant space, the solar system would look like just Sun+Jupiter

JUPITER: THE PLANETARY CHAMPION Mass is 318 times that of Earth = 1.9 x 1030 g Radius is 71,492 km or 11.21 times Earth's. So Density is only 1.33 g/cm3 or 0.241 of Earth's. Vesc=59.5 km/s Period is 11.86 years Semi-major axis is 5.20 AU Eccentricity of 0.048 Inclination to ecliptic =1.3o Axial tilt = 3.08o so little seasonal variation

Jupiter as seen from Earth: Third brightest object in the night sky. 13 moons discovered from the ground. No solid surface: differential rotation. Magnetic (interior) spin period: 9h 55m So fast that ellipticity (1-Rp/Re) is over 6.5%

Views from Earth, Hubble & Cassini

JUPITER'S ATMOSPHERE: Composition Primordial as Vesc = 59.5 km/s 86% H2 by number; 14% He Small amounts of: CH4 , NH3 , H2O, NH4SH; ices provide colors

Jupiter’s Atmosphere: Features BRIGHT ZONES and DARK BELTS Produced by convection currents: Zones are higher pressure: rising warm gas Belts are lower pressure: sinking cool gas Very fast rotation spreads these out E/W Winds up to 400 km/h

Atmospheric Structure NO SOLID SURFACE: Min T (110K) at top of troposphere defines 0 km level There P approx 0.1 PEarth Wien's Law: T = 125K  immense internal heat of formation still leaking out Below this, cloud layers: Ammonia ice (white) Ammonium hydrosulfide (NH4SH) ice (yellow/brown) -- colorations from Sulfur and S compounds Water ice (white/blue) Galileo “lander” probed atmosphere in 1995 & penetrated to -150 km, where T = 400 K, P = 30 Pearth Deep strong winds  internal heating Ethane (C2H6) and phosphine (PH3) found (some coloring) but no organic molecules.

SPOTS and OVALS -- GIANT STORMS Great Red Spot: lasted over 300 years but varies in size -- a persistent storm w/ counterclockwise flow: 2 or 3 earths would fit in it! White Ovals: over 40 years -- high regions Brown Ovals: holes in clouds -- see depths

Details of Atmospheric Flows

JUPITER’S INTERIOR

Interior in Words All numbers are approximate: from best 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 up 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 ~ 5x107 atm; Central T~ 40,000 K Crushed to about 25 g/cm3 at center

Jupiter’s Magnetic Field Interior field is over 20,000 Earth’s; surface field about 14 times Earth’s Energy in magnetic field: millions of times Earth’s Magnetosphere’s tail goes out past Saturn! Inwards, ~30,000,000 km Generated in huge liquid metallic Hydrogen layer: a fast rotating magnetic fluid

Magnetosphere and Aurora Charged plasma ring running through Io’s orbit - made up of gas from its volcanoes Synchrotron radiation and lightning storms in the charged upper atmosphere and inner magnetosphere yield strong radio waves

SPACE MISSIONS TO JUPITER In the 70's Pioneer 10 and 11 flew past Jupiter and sent back close-up photos, discovered a couple small moons and measured the huge extent of the magnetosphere. In the 80's Voyager 1 and 2 went flew past Jupiter, then used its gravity for boosts outwards. Voyager 1 went past Saturn, then flew through its ring system and out of the ecliptic plane (where it measured solar wind and magnetosphere). Voyager 2 used Saturn's gravity to fly past both Uranus and Neptune -- The "Grand Tour".

Voyagers: Gravitational Slingshot

The Galileo Mission In the 90's Galileo flew past Venus and the Earth twice to get gravitational boosts that got it out to Jupiter. Orbited Jupiter for about 8 years, sending back many close-ups of it and its many moons. It dispatched a “lander” which penetrated Jupiter's atmosphere. Galileo crashed into Jupiter in September 2003 so as to avoid ever hitting Europa and possibly contaminating it.

Galileo’s Complex Orbits Swung past various moons to change orbit and get close to other moons on later swings