Jupiter & Jovian Planets!
The Outer Solar System.... differences? Jovians: General Characteristics • BIG - (99.5% total mass!)
• Thick Atmospheres
• NO Solid Surfaces
• rock/ice inner core
• Rings
• LOTS of Satellites
• Rotate FAST (10-17 hours!) Jovian Planets: Masses & Sizes
Planet Mass Mass Radius Radius (kg) (Earth (km) (Earth Radii) masses)
Jupiter 1.898 x 1027 317.7 71,492 11.2
Saturn 5.69 x 1026 95.2 60,268 9.4
Uranus 8.682 x 1025 14.5 25,559 4.0
Neptune 1.024 x 1026 17.1 24,764 3.9 Structure of Gas Giants (Atmospheric) Composition Jupiter (and Saturn) are quite like the Sun: (but very different from Earth)
Percent Sun Jupiter Saturn Earth by mass Atmosphere Atmosphere Atmosphere Hydrogen 74% 75% 92% <1%
Helium 25% 24% 6% 5%
“Metals” 1% 1% 2% 94%
Density of Jovians ~1-2 g/cc (Earth ~ 5.5) What is Metallic H (& He)?
Molecular H & He Metallic H & He
images fr. Burkhard Militzer
High pressure “squishes” molecules: electrons decouple; nuclei become degenerate 7 Jupiter & Saturn GLOW
Jupiter emits 2x as much energy as it receives from the Sun!! WHY?? Emission from Jupiter & Saturn
Conversion of Gravitational Potential Energy into Heat... Just like PROTOSTARS!!
How did Jovians form?? Jupiter
Mass ~ 318 Earth Masses Size - 11.2 Earth Radii (71,492 km) Density - 1.33 g/cc Jupiter is OBLATE
New Horizons flyby
11 RSun = 9.7 RJupiter
RJupiter = 11.2 REarth
RSun ~ 110 REarth Jupiter
Mass ~ 318 Earth Masses Size - 11.2 Earth Radii (71,492 km) Density - 1.33 g/cc Jupiter is OBLATE
Orbital Period - 11.7 years Orbital Distance - 5.2 AU Rotation Period - 9.9 hours “Surface” T (1 bar) - 165 K Core T - >36,000 K Obliquity - 3.1∘
New Horizons flyby Jupiter - Bodacious B (Magnetic Field)
20,000x stronger than Earth!
passes through Saturn’s orbit
Why so Strong? 14 Spinning metallic hydrogen insides create strong magnetospheres • Aurorae! 15 Spinning metallic hydrogen insides create strong magnetospheres • Aurorae! Jupiter’s Atmosphere
Percent Jupiter by mass Atmosphere Hydrogen 75%
Helium 24%
“Metals” 1%
Layered Structure: Methane, Ammonia & deep layer of water or ice droplets. Weather on Jupiter
Belts and Zones differential Rotation
Images from Cassini (Fast) Differential Rotation!! 300-500 km/hr Causes a lot of WEATHER! Jupiter - Great Red Spot
Giant Cyclone
More than one! discovered 1664
rotates in 6 days
BIGGER than Earth!
HST 2006 19 Why is the Red Spot Red?
• The Red Spot is actually quite stuck up, (about 8km).
Galileo Spacecraft, IR Data 1996 Blue: Lower (warmer) Yellow: Higher (cooler) 20 Cassini
Looking inside CONTINENT-SIZED storms.... Cloud colors correspond to HST infrared images. March, 2007. different T Jupiter - Rings
Galileo image Adrastea Preview: Jupiter’s Moons 4 Galilean Satellites
Video: Universe, 23:04 Orbital Motion of the Galilean Satellites
Io: 1.8 days Europa: 3.6 days Ganymede: 7.2 days Callisto: 16.7 days
• Motion is Observable! •Io, Europa, Ganymede are in a Resonance
Animation: A. Cidadao Composition of Galilean Satellites
Average Densities:
Io - 3.5 g/cc Europa - 3.0 g/cc Ganymede - 1.9 g/cc Callisto - 1.8 g/cc
REMEMBER: Rocks - ~3.0 g/cc ??? Ices - 1-2 g/cc xt Ices condense beyond Frost Line! Jupiter is a mini-Solar System!! Adrastea (Many) Moons of Jupiter 63 total at last count
59 outer satellites:
Likely captured asteroids (like Phobos & Deimos) Saturn Orbital Period - 29.4 years Rotation Period - 10.6 hours Saturn is OBLATE Orbital Distance - 9.5 AU
Images from Cassini Saturn Orbital Period - 29.4 years Rotation Period - 10.6 hours Orbital Distance - 9.5 AU
“Surface” T (1 bar) - 134 K Obliquity - 25.3 degrees Seasons?
Images from Cassini Saturn Mass - 95.2 Earth Masses Size - 9.4 Earth Radii (60,268 km) Density - 0.69 g/cc !! Saturn’s Atmosphere
Percent Saturn by mass Atmosphere Hydrogen 96%
Helium 3%
“Metals” 1%
•Bands Similar to Jupiter • why? •Weather! Why so little Helium? Helium Rain on Saturn?
H/He like oil & water Helium Rain (Differentiation): -contributes to internal heat -reduces He in atmosphere Saturn Glows
Why? IR images from Cassini Saturn’s Magnetic Field
-Fast Rotation -Liquid Metallic H/He 33 Saturn’s Rings
1610: Galileo confused
1655: Huygens interpreted as a disk... 34 Saturn’s Rings
1676: Cassini saw the gap in the rings (now named for him)
1883: 1st photo
Why does Saturn have rings?? 35 Roche Limit (Edouard Roche, 1859) Tides! • A distance from a massive body inside which tidal stresses can break up bodies.
• Most of the ring systems are inside the Roche limit 36 Roche Limit (Edouard Roche, 1859) • Comet Shoemaker- Levy 9 broke up inside Jupiter’s Roche limit: Made of dust and water ice particles Adrastea
Moons of Saturn
61 at last count (most recent 2007) 1 Relatively large Satellite
6 Moderate-sized satellites
53 small satellites (similar to Jupiter’s)