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 & SizesPlanet Mass

(kg)Mass (Earth masses)

Radius(km)

Radius(Earth Radii)

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) CompositionJupiter (and Saturn) are quite like the Sun:

(but very different from Earth)Percent by mass

Sun Jupiter Atmosphere

Saturn Atmosphere

Earth Atmosphere

Hydrogen 74% 75% 92%

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??

JupiterMass ~ 318 Earth MassesSize - 11.2 Earth Radii (71,492 km)Density - 1.33 g/cc

New Horizons flyby

Jupiter is OBLATE

11

RSun = 9.7 RJupiterRJupiter = 11.2 REarth

RSun ~ 110 REarth

JupiterMass ~ 318 Earth MassesSize - 11.2 Earth Radii (71,492 km)Density - 1.33 g/cc

Orbital Period - 11.7 yearsOrbital Distance - 5.2 AURotation Period - 9.9 hours“Surface” T (1 bar) - 165 KCore T - >36,000 KObliquity - 3.1∘

New Horizons flyby

Jupiter is OBLATE

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 AtmospherePercent by mass

Jupiter Atmosphere

Hydrogen 75%

Helium 24%

“Metals” 1%

Layered Structure: Methane, Ammonia & deep layer of water or ice droplets.

Weather on Jupiter

Belts and Zonesdifferential Rotation

(Fast) Differential Rotation!! 300-500 km/hr

Images from Cassini

Causes a lot of WEATHER!

Jupiter - Great Red SpotGiant Cyclone

discovered 1664

rotates in 6 days

BIGGER than Earth!

HST 2006

More than one!

19

Why is the Red Spot Red?

• The Red Spot is actually quite stuck up, (about 8km).

IR Data

Blue: Lower (warmer)

Yellow: Higher (cooler)

Galileo Spacecraft, 1996

20

Cassini

Looking inside CONTINENT-SIZED storms....

HST infrared images. March, 2007.

Cloud colorscorrespond to different T

Jupiter - Rings

Galileo image

Preview: Jupiter’s Moons 4 Galilean Satellites

AdrasteaAdrastea

Video:Universe, 23:04

Orbital Motion of the Galilean Satellites

Animation: A. Cidadao

Io: 1.8 daysEuropa: 3.6 days

Ganymede: 7.2 daysCallisto: 16.7 days

• Motion is Observable!•Io, Europa, Ganymede are in a Resonance

Composition of Galilean Satellites

Average Densities:

Io - 3.5 g/ccEuropa - 3.0 g/cc

Ganymede - 1.9 g/cc Callisto - 1.8 g/cc

???

Jupiter is a mini-Solar System!!Ices condense beyond Frost Line!

REMEMBER: Rocks - ~3.0 g/cc Ices - 1-2 g/cc

xt

(Many) Moons of Jupiter63 total at last count

59 outer satellites:

Likely captured asteroids (like Phobos & Deimos)

AdrasteaAdrastea

SaturnOrbital Period - 29.4 yearsRotation Period - 10.6 hoursOrbital Distance - 9.5 AU

Images from Cassini

Saturn is OBLATE

SaturnOrbital Period - 29.4 yearsRotation Period - 10.6 hoursOrbital Distance - 9.5 AU

Images from Cassini

“Surface” T (1 bar) - 134 KObliquity - 25.3 degrees

Seasons?

SaturnMass - 95.2 Earth MassesSize - 9.4 Earth Radii (60,268 km)Density - 0.69 g/cc !!

Saturn’s AtmospherePercent by mass

Saturn 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 & waterHelium 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

1655: Huygens interpreted as a disk...

1610: Galileo confused

34

Saturn’s Rings1676: 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)

• A distance from a massive body inside which tidal stresses can break up bodies.

• Most of the ring systems are inside the Roche limit

Tides!

36

Roche Limit (Edouard Roche, 1859)• Comet Shoemaker-

Levy 9 broke up inside Jupiter’s Roche limit:

Made of dust and water ice particles

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)

AdrasteaAdrastea