© 2005 Pearson Education Inc., publishing as Addison-Wesley Giant Planets Jupiter Saturn Uranus...

© 2005 Pearson Education Inc., publishing as Addison-Wesley

Giant PlanetsGiant Planets

Jupiter

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Saturn

Uranus

Neptune


Important Notes:Important Notes:

• Read Chapter 11: “Jovian Planet Systems”Read Chapter 11: “Jovian Planet Systems”• Homework #8 due Friday Homework #8 due Friday

(on today’s and Thursday’s lecture)(on today’s and Thursday’s lecture)• MarsMars: Mark mid-semester position!: Mark mid-semester position!

• Midterm #2: Tuesday, April 15Midterm #2: Tuesday, April 15


The Solar SystemThe Solar SystemTerrestrial (Rocky) Outer 4 Planets: Gaseous Giants


The 4 “Giant Planets”The 4 “Giant Planets”“Jovian Planets”:“Jovian Planets”:



Much higher mass & radius than Earth, Venus, Mars.• No solid surfaces !!!


are needed to see this picture. H & He

(most common atoms in universe)

(text: “hydrogen compounds” = water, methane, ammonia)

“Ice Giants”

Jupiter Saturn Uranus Neptune

All have Rock Cores: 10-15 Earth-Masses

H & He H2O,

H & He

H2O,

H & He


Jupiter’s Moon: Io

• A volcanic explosion can be seen silhouetted against dark space over Io's brilliant limb. Io more volcanically active than Earth.



Next Lecture:Next Lecture:

Moons orbiting the Giant PlanetsMoons orbiting the Giant Planets


Jupiter – King of the PlanetsJupiter – King of the PlanetsMass = 0.001 solar (318 earths), Radius = 11.2 Earths, Density = 1.3 g/cc (1.3 x water)

Distance: 5.2AUOrbital Period: 11.8 years Rotation period: 9.9 hours.

Flattened Spheroid


SaturnMass = 95 EarthsRadius = 9.4 Earths Density = 0.7 gram/cm3 (floats)Distance: 9.5 AUOrbital Period: 29.4 yearsRotation period: 10.6 hours.

Rings: Composed ofbillions of icy-rocks and icy dust (water and silicates).


UranusUranusMass = 14.5 Earths Orbital Period: 84 years; Radius = 4.0 EarthsDensity = 1.3 gram/cm3 = 1.3 x water Distance: 19.2 AU Rotation period: 17.2 hours.

Visible Light Infrared Light (Thermal Emission)

•Featureless in visible light, because clouds

are below haze layer of methane (colder than Saturn).


NeptuneNeptune


Neptune

Mass = 17 Earths

Radius = 3.9 Earths

Density = 1.76 x water

Distance: 30 AU

Orbital Period: 163 years;

Rotation period: 16.1 hours.

Cyclonic storms.


GIANT PLANETS


Spacecraft Reconnaisance







1980’s: Voyager 1 & 2

Camera

Spectrometer

Visit all 4

giant planets

Measures spectral lines:

Chemical composition


Spacecraft Reconnaisance;

Galileo Spacecraft

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•Launched from Space Shuttle 1989


Spacecraft Reconnaisance;

Galileo Spacecraft





Arrived: 1995

2003:Dropped into Jupiter’s

Atmosphere:

Measure Chemical

Composition:

97% hydrogen & helium

Plus 3% C, N, O, S, Si …


C, N, O, HChemistry

Giant Planet’s Chemical CompositionGiant Planet’s Chemical Composition

Mostly Hydrogen and HeliumMostly Hydrogen and Helium

•Add H to:

C, N, O


Why are the Jovian Planets Massive and Gaseous (H, He) ?

• Formed beyond the frost line (3 AU): so cold that ice particles exist with silicate dust.

• Ice and Dust collides, sticks grows into icy-rocky core.• Core’s gravity captures H/He gas• Planet attracts ices and dust that orbit• Moons formed out of these disks: A miniature solar system.

Young Solar System:

Gas & Dust

Young Jupiter


Quiz

If Jupiter formed in a protoplanetary disk that had twice as much dust it:

a) Would have a bigger core

b) Might have more hydrogen

c) Might have more metallic hydrogen

d) All of the above




• Color Enhancement


Hydrostatic Equilibrium: Pressure balanceHydrostatic Equilibrium: Pressure balance

“Hydrostatic equilibrium” governs the structure of all planets. The inside has higher pressure and density because of the weight of the overlying material.

Pressure at any depth = gravitational weight of column above


Inside Jupiter• Jupiter emits almost twice as much energy as it absorbs from the Sun.

• accretion, differentiation, radioactivity can not account for it

• Jupiter must still be contracting

• Jupiter has 3 x more mass than Saturn, but is only slightly larger in radius!• the added weight of H & He compresses the core to a higher density

• like stacking pillows• If Jupiter had 10x its mass,

it would have same radius ! Add even more mass, and Jupiter would get smaller !

• Jupiter is about as large as a planet can get.

• Uranus & Neptune have less mass than Saturn, yet

they have higher densities

• They must be made of denser material:

• Rock & Ice !


Quiz

On the moon, a cup of sugar has some pressure, P, at its bottom. You add 50% more sugar to the cup. The new pressure at the bottom is:

a) 0.5 P

b) 1.0 P

c) 1.5 P

d) 2.0 P


Inside Jupiter

• Moving from the surface to the core:• temperature increases• pressure & density increases

• Hydrogen atoms so dense: Electrons not associated with

any one atom: Free- electrons. Metallic Hydrogen!

• Jupiter's core is rock & ice: ~10 times the mass of Earth.

. . . Controversial.

No solid surface and consists mostly of H & He.Distinct interior layers, defined by increasing density inward.


Inside the Jovian Planets• All Jovian cores appear to be similar.

• made of rock, metal, and Hydrogen compounds• 10 x the mass of Earth

• Uranus & Neptune captured less gas from the Solar nebula.• accretion of planetesimals took longer• not much time for gas capture before nebula was cleared out by Solar wind

• Only Jupiter and Saturn have high enough pressure for H & He to exist in liquid and metallic states.


Centrifugal Force:

Flings material at equator outward

Due to Rotation

Rotational Distortionof Planet’s Shape


Rotation flattens shape—> Less pull on satellite at poles

Higher densitytoward center —> Exerts Point-like Grav. Force

Track acceleration ofTrack acceleration ofsatellites accuratelysatellites accurately

—> Density throughout interiorDensity throughout interior

Determining the Density inside a Rotating PlanetUse Motion of Orbiting Satellites


The Great Red Spot



- Another Effect of Planet’s Rotation -




A Hurricane that has

lasted 300 yearsGreat Red SpotGreat Red Spot


Cyclonic MotionsCyclonic Motions

Coriolis effect: Coriolis effect: Motion fromMotion fromHigh PressureHigh Pressure area area

NorthernNorthernHemisphereHemisphere

SouthernSouthernHemisphereHemisphere


Jovian Storms• Red Spot: A High Pressure Storm

• Analogous to hurricanes, but they rotate in the opposite direction

• Jupiter• the Great Red Spot• we are not sure why it is red

• Neptune• the Great Dark Spot

Planet

Rotation


scooter

Neptune’s

Storms


Quiz

You are standing on the equator of the Earth and you throw a ball fast, directly toward the south pole. The ball’s trajectory will

a) Carry it toward the south pole

b) Veer to the right

c) Veer to the left

d) Curl around in a spiral


Jupiter’s Cloud Layers

• Convection in the troposphere causes Jovian weather.

• Warm gas rises to cooler altitudes, where it condenses to form clouds.

• Three gases condense in the Jovian atmosphere:• ammonia (NH3)

• ammonium hydrosulfide (NH4SH)

• water (H2O)

• They condense at different temperatures, so their clouds form at different altitudes.

Alt

itud

e ab

ove

clou

ds to

ps (

km)

Temperature (C )


The Jovian Atmospheres

• The temperature profile of each planet determines the color of its appearance.

• Cloud layers form where a particular gas condenses.

• Saturn has the same cloud layers as Jupiter.• they form deeper since Saturn is

colder overall

• they are spread farther apart since Saturn has lower gravity

• Uranus & Neptune• cold enough to form methane clouds


Bands of JupiterWhat Causes them?


Convection on Jupiter:

•Warm air rises•Coriolis force

diverts path sideways

Coriolis force is due to

rotation of planet

•Jupiter rotates fast:

Period = 10 hours


Wind Speed in Jupiter’s Bands

•1000 km/hr


Red SpotRed Spotin Southernin SouthernHemisphereHemisphere

Winds of Jupiter’s Bands


Magnetic FieldsJupiter Saturn

Uranus Neptune


Jupiter's Magnetosphere

• Ion and neutral mass spectrometer instrument on the Cassini spacecraft, makes the huge magnetosphere surrounding Jupiter visible. The magnetosphere is a bubble of charged particles trapped within the magnetic environment of the planet. In this picture, a magnetic field is sketched over the image to place the energetic neutral atom emissions in perspective.

• Also shown for scale and location are the disk of Jupiter (black circle) and the approximate position (yellow circles) of the doughnut-shaped torus created from material spewed out by volcanoes on Io, one of Jupiter's large moons.




Jupiter’s Magnetosphere – Bigger than the Sun

Solar Wind

protons &

electrons


Jovian Magnetospheres

• Saturn, Uranus, & Neptune have smaller & weaker magnetospheres.• fraction of electrically conducting material in interiors is smaller

• Solar wind is weaker farther out, or else their magnetospheres would be even smaller

• we can not explain the magnetic field tilts of Uranus & Neptune.


Auroral ZonesThe high energy particles come down the field lines and hit the atmosphere near the poles, causing the gases to glow. Just like on the Earth, this makes an “aurora” in a ring-like zone.


The 4 “Jovian” Worlds

• Major features : Massive: 14 - 300 x mass of Earth Gaseous: Hydrogen, Helium & Water Rocky Core (Si, O, Fe, Ni …) Rotating Fast: 10 hours (squashed shape)

© 2005 Pearson Education Inc., publishing as Addison-Wesley Giant Planets Jupiter Saturn Uranus...

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