Jovian Planet Systems - (Chpt11)

8/6/2019 Jovian Planet Systems - (Chpt11)

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Chapter 11

Jovian Planet Systems


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11.1 A Different Kind of Planet

Our goals for learning Are jovian planets all alike?

h t re o i n l nets like on the inside?

What is the weather like on jovian planets?

Do jovian planets have magnetospheres like

Earths?


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Are jovian planets all alike?


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Jovian Planet Composition

Jupiter and Saturn

Mostly H and He gas

Mostly hydrogen compounds: water (H2O),methane (CH4), ammonia (NH3)

Some H, He, and rock


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Density Differences

1.5

2

(g/cc)

Uranus and Neptune

0

0.5

JupiterSa

turnUr

anus

Neptune

Densit

because they have less

H/He, proportionately


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Density Differences

1.5

2

(g/cc) But that explanation

doesnt work for

0

0.5

JupiterSa

turnUr

anus

Neptune

Densit

.


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Sizes of Jovian Planets

Adding mass to a

jovian planetcompresses theunderlying gas

layers


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Sizes of Jovian Planets Greater compression

is why Jupiter is notmuch larger thanSaturn even though it

massive

Jovian planets with

even more mass canbe smaller thanJupiter


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Rotation and Shape

Jovian planets are

not quite sphericalbecause of theirrapid rotation


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What are jovian planets like onthe inside?


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Interiors of Jovian Planets

No solid surface. Layers under high pressure and

.

Cores (~10 Earth masses) made of hydrogen

compounds, metals & rock

The layers are different for the differentplanets. WHY?


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Inside Jupiter

High pressures

inside Jupiter causephase of hydrogen

to change with depth

Hydrogen acts like a

metal at great depths

because its electronsmove freely


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Inside Jupiter

Core is thought to

be made of rock,metals, and

hydrogen

compounds

Core is about same

size as Earth but 10times as massive


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Comparing Jovian Interiors

Models suggest cores of jovian planets have similar

composition Lower pressures inside Uranus and Neptune mean no

metallic hydrogen


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Jupiters Internal Heat

Jupiter radiates

twice as muchenergy it receives

from Sun

Energy probably

comes from slow

contraction ofinterior (releasing

potential energy)


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Internal Heat of Other Planets

Saturn also radiates twice as much energy itreceives from Sun

(helium rain)

Neptune emits nearly twice as much energy

as it recieves, but the source of that energyremains mysterious


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What is the weather like onjovian planets?


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Jupiters Atmosphere

Hydrogen

compounds inJupiter form clouds

Different cloudlayers correspond to

freezing points of

different hydrogencompounds

H2O

NH4SH

NH3


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Jovian Planet Atmospheres

Other jovian planets

have cloud layerssimilar to Jupiters

Differentcompounds make

clouds of different

colors


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Jupiterscolors

Ammonium sulfide clouds (NH4SH) reflect red/brown.

Ammonia, the highest, coldest layer, reflects white.


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Saturns

colors

Saturns layers are similar, but deeper in and

farther from the Sun --- more subdued.


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Methane on Uranus and Neptune Methane gas of

Neptune and Uranusabsorb red light but

transmit blue light

Blue light reflects

off methane clouds,

making those planeslook blue


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Jupiters BandsWhite ammonia

clouds form

where air rises Coriolis effectchanges N-S

flow to E-W

windsBetween white

deeper reddishclouds of

NH4SH

Warmer red bands

are brighter in IR


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Jupiters

Great

Red

A storm twice as wide as Earth

Has existed for at least 3 centuries


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Weather on Jovian Planets

All the jovian planets have strong winds and

storms


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Do jovian planets havemagnetospheres like Earths?


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Jupiters Magnetosphere

Jupiters strong magnetic field gives it an enormousmagnetosphere

Gases escaping Io feed the donut-shaped Io torus

Aurora on Jupiter


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Thought QuestionJupiter does nothave a large metal core like

the Earth. How can it have a magnetic field?

a) The magnetic field is left over from when Jupiter

accreteb) Its magnetic field comes from the Sun

c) It has metallic hydrogen inside, which circulates

and makes a magnetic fieldd) Thats why its magnetic field is weak


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Thought QuestionJupiter does nothave a large metal core like

the Earth. How can it have a magnetic field?

a) The magnetic field is left over from when Jupiter

accreteb) Its magnetic field comes from the Sun

c) It has metallic hydrogen inside, which circulates

and makes a magnetic fieldd) Thats why its magnetic field is weak


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What have we learned?

Are jovian planets all alike?

Jupiter and Saturn are mostly H and He gas

Uranus and Nepture are mostly H compounds

What are jovian planets like on the inside?

ayere nter ors w t very g pressure ancores made of rock, metals, and hydrogencompounds

Very high pressure in Jupiter and Saturn can

produce metallic hydrogen


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What is the weather like on jovian planets?

Multiple cloud layers determine colors of

jovian planets All have strong storms and winds

like Earths? All have substantial magnetospheres

Jupiters is largest by far


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11.2 A Wealth of Worlds: Satellites ofIce and Rock

Our goals for learning What kinds of moons orbit jovian planets?

h re iters lile n moons so

geologically active? What is special about Titan and other major

moons of the solar system?

Why are small icy moons more geologicallyactive than small rocky planets?


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What kinds of moons orbit thejovian planets?


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Sizes of Moons

Small moons (< 300 km) No geological activity

- - ,

Geological activity in past

Large moons (> 1,500 km)

Ongoing geological activity


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Medium &

Large Moons

Enough self-gravity tobe spherical

Have substantial

amounts of ice. Formed in orbit

around jovian planets.

Circular orbits in samedirection as planet

rotation.


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SmallMoons

Far more numerous than the medium and large

moons. Not enough gravity to be spherical: potato-

shaped


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SmallMoons

Captured asteroids or comets, so orbits do

not follow usual patterns.


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Why are Jupiters Galileanmoons so geologically active?


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Ios Volcanoes

Volcanic eruptions continue to change Ios surface


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Tidal Heating

Io is squished and

stretched as it orbits

Jupiter But why is itsorbit so

elliptical?

O bit l


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Orbital

Resonances

The tugs add up over

time, making all 3orbits elliptical.

Every 7 days,

these 3 moonsline up.


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Europas Ocean: Waterworld?


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Tidal stresses crack Europassurface ice.


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Europas interior also warmed by tidal heating


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Ganymede

Largest moon in the

solar system

Clear evidence of

geo og ca act v ty

Tidal heating plus

heat from radio-

active decay?


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Callisto Classic cratered

iceball. No tidal heating,

resonances. But it has

magnetic field !?


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Thought QuestionHow does Io get heated by Jupiter?

a) Auroras

b) Infrared Light

c) Jupiter pulls harder on one side than the otherd) Volcanoes


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Thought QuestionHow does Io get heated by Jupiter?

a) Auroras

b) Infrared Light

c) Jupiter pulls harder on one side than the otherd) Volcanoes

What is special about Titan and


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What is special about Titan and

other major moons of the outersolar system?


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Titans Atmosphere Titan is the only

moon in the solarsystem to have a

thick atmosphere

It consists mostly of

nitrogen with some

argon, methane, andethane


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Titans Surface

Huygens probe provided first look at Titans surface inearly 2005

Liquid methane, rocks made of ice


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Medium Moons of Saturn

Almost all show evidence of past volcanismand/or tectonics


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Medium Moons of Uranus Varying amounts of

geological activity

Moon Miranda has

large tectonicfeatures and few

craters (episode of

tidal heating inpast?)


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Neptunes Moon Triton Similar to Pluto, but

larger

E idence for ast

geological activity

Why are small icy moons more


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Why are small icy moons more

geologically active than smallrocky planets?

Rocky Planets vs Icy Moons


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Rocky Planets vs. Icy Moons

Rock melts at higher

temperatures

Only large rocky

planets have enough

heat for activity

Ice melts at lower

temperatures

Tidal heating can

melt internal ice,

driving activity



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What kinds of moons orbit jovian planets?

Moons of many sizes

Level of geological activity depends on size

Why are Jupiters Galilean moons so

Tidal heating drives activity, leading to Iosvolcanoes and ice geology on other moons



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What is special about Titan and other major

moons of the solar system?

Titan is only moon with thick atmosphere Many other major moons show signs of geological

activity

Why are small icy moons more geologicallyactive than small rocky planets?

Ice melts and deforms at lower temperatures enabling

tidal heating to drive activity


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11.3 Jovian Planet Rings

Our goals for learning

What are Saturns rings like?

Ho do other o i n rin s stems com re

to Saturns? Why do the jovian planets have rings?


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They are made up of numerous, tinyindividual particles

They are very thin


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Earth-based view


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Spacecraft view of ring gaps


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Artists conception of close-up


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Gap Moons Some small moons

create gaps within

rings


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Shepherd Moons

Pair of small moons can force particles into a narrow ring


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Resonance Gaps Orbital resonance

with a larger moon

can also produce a

gap


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How do other jovian ring systemscompare to Saturns?


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Why do the jovian planets haverings?


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Why do the jovian planets haverings?

They formed from dust created in impacts

on moons orbiting those planets

How do we know that?


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Ring Formation


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Ring Formation

Jovian planets all have rings because they

possess many small moons close-in

Impacts on these moons are random Saturns incredible rings may be an accident

of our time



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Made up of countless individual ice particles

Extremely thin with many gaps How do other jovian ring systems compare

Much fainter ring systems with smaller,darker, less numerous particles

Why do the jovian planets have rings?

Ring particles are probably debris frommoons


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Thought QuestionWhat would happen to Earths temperature if Earth

were more reflective?

a) It would go up.

b) It would go down.

c) It wouldnt change


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Thought QuestionIf Earth didnt have an atmosphere, what would

happen to its temperature?

a) It would go up a little.

b) It would go up a lot.

c) It would go down a little.

d) It would go down a lot.

e) It would not change.

Thought Question


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g Q

If Earth didnt have an atmosphere, what would

happen to its temperature?

a) It would go up a little.

b) It would go up a lot.

c) It would go down a little.

d) It would go down a lot.

e) It would not change.

Thought Question


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g Q

Why is the sky blue?

a) The sky reflects light from the oceans.

b) Oxygen atoms are blue.

c) Nitrogen atoms are blue.

d) Air molecules scatter blue light more than red light.

e) Air molecules absorb red light.

Thought Question


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g Q

Why is the sky blue?

a) The sky reflects light from the oceans.

b) Oxygen atoms are blue.

c) Nitrogen atoms are blue.

d) Air molecules scatter blue light more than red light.

e) Air molecules absorb red light.

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Jovian Planet Systems - (Chpt11)