Giant Planets Jupiter Saturn Uranus Neptune. Notes: Read Chapter 11: “Jovian Planet Systems”...

Giant Planets

Jupiter

Saturn

Uranus

Neptune

Notes:

Read Chapter 11:

“Jovian Planet Systems”

Homework: in Mastering Astronomy due Friday.

Results from Midterm 1

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

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

Spacecraft Reconnaisance1980’s: Voyager 1 & 2

Camera

Spectrometer

Visited all 4

giant planets

Measures spectral lines:

Chemical composition

Voyager SpacecraftMovie of Jupiter

Approach of Voyager SpacecraftIn Rotating Frame of Reference

• This is the original Voyager 'Blue Movie' (so named because it was built from blue filter images). It records Voyager 1's approach during a period of 60 Jupiter days. Notice the difference in speed and direction of the various zones of the atmosphere.

Voyager SpacecraftMovie of Jupiter:

In Rotating Frame of Reference

Galileo SpacecraftVisited Jupiter

• Launched from Space Shuttle 1989

Galileo SpacecraftArrived: 1995

2003:Dropped into Jupiter’s

Atmosphere:

Measure Chemical

Composition:

The 4 “Giant Planets”“Jovian Planets”

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

H & He (most common

atoms in universe)

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

“Ice Giants”

Jupiter Saturn Uranus Neptune

All have rocky cores (silicates+iron) of 10-20 Earth masses

H & He H2O,

H & He

H2O,

H & He

Comparison of Sun’s and Jupiter’s composition (as measured by the

Galileo Probe)

Jupiter Sun Jupiter Sun

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

Fractional composition in mass %.

H 0.742 0.736 Ne 0.00023(3) 0.0018

He 0.231(4) 0.249 P < 0.00007 0.00001

C 0.009(2) 0.0029 S 0.00091(6) 0.00050

N < 0.012 0.00085 Ar < 0.00015 0.00007

O < 0.0035 0.0057 “Z” 0.027 0.015


Jupiter – King of the PlanetsMass = 0.001 solar (318 Earth masses), Radius = 10.5 … 11.2 Earth radii, Density = 1.3 g/cc (1.3 x water)

Distance: 5.2AUOrbital Period: 11.8 years Rotation period: 9:55 hours.

Flattened Spheroid

11.2 RE

10.5 RE


SaturnMass = 95 Earths (only 30% of Jupiter)

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

Rings: Composed of billions of icy rocks and icy dust particles (water ice and silicates).

Interior of Jupiter and Saturn

“Phases” of Hydrogen: The Interiors of Jupiter & Saturn

Density

Tem

per

atu

re (

K)

Phases of Hydrogen

Computer Simulation: Molecular and Metallic hydrogen

Molecular hydrogen

Metallic hydrogen

• Electrons free to move• Electrons bound to molecules

“Phases” of Hydrogen: The Interiors of Jupiter & Saturn

Density

Tem

per

atu

re (

K)

Phases of Hydrogen

A New Probe of Jupiter: “Juno”Launch August 5, 2011

Interior of JupiterA New Probe: “Juno”

Surfaces of theGiant Planets

Jupiter

Jupiter’s Atmospheric Properties

Rotation Period = 9 hours 55 minutes

(based on Jupiter’s magnetic field)

Cassini (2000)

Rotation Period = 9 hours 55 minutes

(based on Jupiter’s magnetic field)

Cassini (2000)

Jupiter’s Atmosphere

Cassini (2000)

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

Bands of JupiterWhat Causes them?

Red Spotin SouthernHemisphere

Winds of Jupiter’s Bands


A Hurricane that has

lasted 300 yearsGreat Red Spot

Giant red spot in motion

Giant red spot in motion

Red Oval in motion

Red Oval in motion

Cyclones and Anticyclones on Jupiter

Computer Simulation of Cyclone Formation

Red Spot Jr. spot formed from three white ovals and later turned red.

Cyclonic Motions

Coriolis effect: Motion fromHigh Pressure area

NorthernHemisphere

SouthernHemisphere

Cyclones: • Low pressure weather phenomena, • Winds blow inwards,• Typical storm systems on Earth• Rotate counter-clockwise on Northern

hemisphere, • Rotate on clockwise on Southern

hemisphere,

Anti-Cyclones: • High-pressure weather phenomena, • Winds blow outwards,• Example: Jupiter’s red spot• Rotate clockwise on Northern

hemisphere, • Rotate counter-clockwise on Southern

hemisphere,

Comparison of Cyclones and Anti-Cyclones

(A) Anti-cyclone on northern HS

(B) Cyclone on the northern HS

(C) Anti-cyclone on the southern HS

(D) Cyclone on the southern HS

What is this?

Cyclones: • Low pressure weather phenomena, • Winds blow inwards,• Typical storm systems on Earth• Rotate counter-clockwise on Northern

hemisphere, • Rotate on clockwise on Southern

hemisphere,

Anti-Cyclones: • High-pressure weather phenomena, • Winds blow outwards,• Example: Jupiter’s red spot• Rotate clockwise on Northern

hemisphere, • Rotate counter-clockwise on Southern

hemisphere,

Comparison of Cyclones and Anti-Cyclones

What is this?

(A) Anti-cyclone on northern HS

(B) Cyclone on the northern HS

(C) Anti-cyclone on the southern HS

(D) Cyclone on the southern HS

Jovian StormsRed Spot: A High Pressure Storm

• Analogous to hurricanes (low pressure systems, material flows in), but they rotate in the opposite direction because they high pressure systems where material flow out

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

Neptune• the Great Dark Spot

Planet

Rotation

Uranus – Haze but any Clouds?Mass = 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).

Visible Light

• Featureless in visible light, because clouds

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

Uranus – Yes Plenty of Clouds

Uranus – Yes Plenty of Clouds

NeptuneMass = 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.

Uranus & Neptune Giants of H, He, and Water!

Rocky core (silicates+iron)

Liquid mixture of H2O, CH4, NH3 ices

Gaseous envelope of H, He, and some CH4


Hydrostatic 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 Giant PlanetsSaturn emits almost twice as much energy as it absorbs from the Sun.

• Neither Cooling nor Radioactivity can account for it• Saturn must a different “secret” heat source

Jupiter has 3x more mass than Saturn, but is only slightly larger in radius!• the added weight of H & He compresses the gases below 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 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:

More Rock & Water !

How do you construct a model for Jupiter’s interior?

A typical Jupiter model is based on1) Hydrogen-helium

relationship between pressure-density-temperature

2) Abundance of all atoms from measurements (Galileo probe)

3) Gravitational “shape”, inferred from fly-by trajectories (Galileo & Cassini missions)

R

Rotation flattens shape —> Less pull on satellite at poles

Higher densitytoward center —> Exerts Point-like Gravitational Force

Track acceleration ofsatellites accurately

—> Density profile throughout interior

Determining the Density inside a Rotating PlanetUse Motion of Orbiting Satellites

Interactive Quiz

How would you land on Jupiter?

(A)With parachutes

(B) With thrust rockets

(C) With pontoons like a seaplane

(D) You cannot land on Jupiter.

How would you land on Jupiter?

(A)With parachutes

(B) With thrust rockets

(C) With pontoons like a seaplane

(D) You cannot land on Jupiter.

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.How many Jovian moons are there?

Thursday’s Lecture:

Moons orbiting the Giant Planets


Jupiter – King of the Planets Radius = 10.5 … 11.2 Earth radii

Make a bigger Earth that has a radius 10 times larger. Assume the density would be the same, what would its mass be?

(A)The same, one Earth mass

(B) 10 Earth masses

(C) 100 Earth masses

(D) 1000 Earth masses



(B) 10 Earth masses




Jupiter – King of the Planets Radius = 10.5 … 11.2 Earth radii



(B) 10 Earth masses





(B) 10 Earth masses



But Jupiter’s mass is only 318 Earth masses. What does this tell us?


Size of Rocky Planets

Make the Earth a 1000 times more massive. How large would its radius be?

(A)The same, one Earth radius

(B) 3 Earth radii

(C) 6 Earth radii

(D) 10 Earth radii



(B) 3 Earth radii

(C) 6 Earth radii

(D) 10 Earth radii


Size of Rocky Planets



(B) 3 Earth radii (because of gravity!!)

(C) 6 Earth radii

(D) 10 Earth radii



(B) 3 Earth radii (because of gravity!!)

(C) 6 Earth radii

(D) 10 Earth radii


Saturn’s

Storms


After 15 years of winter on Saturn’s Northern hemisphere, spring arrives with gigantic storms


scooter

Neptune’s

Storms

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) (high altitude)

• ammonium hydrosulfide (NH4SH)

• water (H2O)

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

A

ltit

ude

abov

e cl

ouds

tops

(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

Aurora Borealis near Jupiter’s North Pole


Auroral ZonesThe high energy particles come down the magnetic 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.

Magnetic FieldsJupiter Saturn

Uranus Neptune


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.


Inside the Jovian PlanetsAll 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.

Quiz

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

(A)Would have a bigger core

(B) Might have more hydrogen

(C) Might have more metallic hydrogen

(D)All of the above

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


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 gasPlanet attracts ices and dust that orbitMoons formed out of these disks: A miniature solar system.

Young Solar System:

Gas & Dust

Young Jupiter

Giant Planets Jupiter Saturn Uranus Neptune. Notes: Read Chapter 11: “Jovian Planet Systems”...

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