1
The Jovian Planets

Huge worlds, heavily mantled in gas at the time of the formation of the
Solar System.
2
Composition of the Jovian Planets

Jupiter and Saturn attracted so much gas gravitationally during
formation that the have a composition that largely matches the Sun

Mostly hydrogen, some helium, and a a tiny fraction of the other
elements.
3
Composition of the Jovian Planets

Jupiter and Saturn attracted so much gas gravitationally during
formation that the have a composition that largely matches the Sun

Mostly hydrogen, some helium, and a a tiny fraction of the other
elements.
- Uranus and Neptune
are also dominate by
Hydrogen and Helium, but
not to the degree that
Jupiter and Saturn are.
- The significant portion of
their mass likely made up
by water leads to Uranus
and Neptune being called
“ice giants”
4
Composition of the Jovian Planets


Under the immense pressure of the “atmosphere” hydrogen and
helium behave more like liquids in the interior.
Only the outermost layers are recognizable as “atmosphere”
5
Jovian Planet Surfaces

There aren't any... The cloudtops provide an apparent surface, but
beneath is nothing but gas of increasing density.

The “cartoon” cores do not represent a surface either (in the same
way as you would not regard the Earth's core as a “surface”).
6
Jovian Cloud Composition

Jovian planets, particularly Jupiter and Saturn, have “cloud decks” of
different composition.
7
Jovian Cloud Composition

The highest (and whitest) clouds are ammonia.

Next deepest is ammonium hydrosulfide, and deeper still is water.
8
Jovian Cloud Composition

The highest (and whitest) clouds are ammonia.

Next deepest is ammonium hydrosulfide, and deeper still is water.
9
Jovian Cloud Composition

For Uranus and Neptune it is cold enough that the high cloud decks
are frozen methane.
10
Jupiter vs. Saturn

Jupiter's cloud features are more sharply defined than Saturn's
because Saturn's cloud decks form lower in the atmosphere.
11
Learning about the Jovian Planets

Earth-based telescopes can provide plenty of analytic information
about atmospheric composition and bulk weather on Jovian worlds but
the view is fuzzy because of our distance.
12
Learning about the Jovian Planets

Going there makes a huge difference....
13
Voyager

Two Voyager spacecraft were launched in 1977 and arrived at Jupiter
in 1979. One of the two visited Jupiter, Saturn, Uranus and Neptune
– the last in 1989.
14
Visits to Jupiter

Pioneer flyby(s) - 1973/4

Voyager flyby(s) - 1979

Galileo orbiter - 1995

Cassini flyby - 2000 (on the way to orbit Saturn in 2004)

New Horizons flyby – 2007 (on the way to fly by Pluto in 2015)
15
16
Visits to Jovian Planets



Jupiter

Pioneer 10 and 11

Voyager 1 and 2

Galileo Orbiter

Cassini (boost to Saturn)

New Horizons (boost to Pluto)

Juno (in transit – arrival 2016)
Saturn

Pioneer 10 and 11

Voyager 1 and 2

Cassini orbiter
Uranus and Neptune

Voyager 2
17
Don't Forget the Moons

These spacecraft also provided detailed views of numerous satellites
of these Jovian worlds.
18
Rapid Rotation

All Jovian planets rotate rapidly. Jupiter completes a rotation in just
under 9 hours.

The rapid spin leads to significant “flattening”

The shape of the planets gives away information about the cores.
19
Rapid Rotation

Rapid rotation also leads to banded
atmospheric circulation – belts and
zones.

These bands correspond to
terrestrial high and low pressures
systems

sinking and rising atmosphere
respectively.
20
Rapid Rotation

Rapid rotation also leads to banded
atmospheric circulation – belts and
zones.

These bands correspond to
terrestrial high and low pressures
systems

sinking and rising atmosphere
respectively.
21
Hadley Circulation
22
23
Oval Storms on Jupiter

The scale of the Great Red Spot
24
The Great Red Spot

The scale of the Great Red Spot
25
Planetary Magnetic Fields

Rapid rotation combined with a liquid metallic interior leads to the
generation of an intense magnetic field
Liquid
Metal
Core?
Rapid
Rotation?
Strong Magnetic
Field?
Mercury
No
No
No
Venus
Yes
No
No
Earth
Yes
Yes
Yes
Mars
No
Yes
No
Jupiter
Yes
Yes, Yes
Huge
Saturn
Yes
Yes, Yes
Huge
Uranus/
Neptune
Salty
slush?
Yes
Yes
26
Interaction with the Solar Wind

Planetary magnetic fields shield planets from the solar wind and cause
energetic particles to interact with the planet's atmosphere causing
auroral emission.
27
Magnetospheres

Planetary magnetic fields shield planets from the solar wind and cause
energetic particles to interact with the planet's atmosphere causing
auroral emission.
28
Jupiter's Immense Magnetic Field

Rapid rotation combined
with a liquid metallic interior
leads to the generation of a
magnetic field so strong that
its influence extends beyond
Saturn's orbit.
29
Aurorae

Planetary magnetic fields guide high-energy solar wind particles to the
planetary poles

The interaction of these particles with atmospheric gases makes the
gases emit spectral line radiation causing aurorae.
30
Jupiter's Aurora
31
Aurorae on Earth

The aurora borealis/australis (also known as the “northern lights” is
typically a phenomenon observed at northerly latitudes.
32
Earth's Aurora
33
Earth's Aurora
34
Why isn't Jupiter a Star?

It's made of the same mix of elements as the Sun.

It's similar in size.
35
Why isn't Jupiter a Star?

Jupiter may be 1/10th the diameter of the Sun, but it has 1/1000th the
mass of the Sun – therein lies the key difference.
36
What Keeps the Sun Shining

The Sun has maintained its current luminosity of
400,000,000,000,000,000,000,000,000 (4x1026) Joules/second for the
past 4.6 billion years.

A 100 Watt lighbulb consumes 100 Joules/second

World energy demand is about 1 trillionth of this rate.

The Sun emits enough energy every second to supply the world
for a million years.
37
What Keeps the Sun Shining

The Sun has maintained its current luminosity of
400,000,000,000,000,000,000,000,000 (4x1026) Joules/second for the
past 4.6 billion years.

A 100 Watt lighbulb consumes 100 Joules/second

World energy demand is about 1 trillionth of this rate.


Where does this energy come from?


The Sun emits enough energy every second to supply the world
for a million years.
Chemical burning last only 10,000 years. Gravitational contraction
would supply energy for 10 million years.
The Answer
E=
2
mc
38
E=mc2




Matter and Energy are interchangeable quantities, if
you have the right tools.
Einstein's famous formula gives the conversion rate.

c is the speed of light (3x108 meters/sec) – a
huge number... squared here.

a small amount of matter represents a huge
amount of energy.
A penny has a mass of 2.5 grams

converted to energy it could keep a 100 watt
light bulb shining for 100,000 years.

or supply the world's energy needs for 20
seconds.

or lay waste to a large city....
This 100% conversion is possible if you are able to
mix equal quantities of matter and antimatter.
39
E=mc2 at 0.7% Efficiency

Hydrogen under pressure and heated to 10's of millions of degrees will
fuse to form Helium.

High temperatures get protons moving fast enough to overcome the
repulsive force of their like charges.
40
E=mc2 at 0.7% Efficiency

At these high speeds the protons can get close enough for the strong
nuclear force to take over and fuse them together.

By the end of the process 0.7% of the mass has disappeared.

This small efficiency is enough to have kept the Sun shining for 4.6
billion years.
41
A Hot Solar Interior

Just as when you descend from a mountain it gets hotter as you go
deeper into the Earth's atmosphere, the crushing pressure of the
Sun's outer layers make the Sun's interior immensely hot.
42
A Hot Solar Interior

The expected central temperature of about 15 million degrees is just
right for thermonuclear fusion to occur.

Jupiter comes up quite short, reaching a central temperature of a few
10's of thousands of degrees.
43
Solar Neutrinos
Each fusion of a pair of protons to form a deuteron produces an
energetic neutrino.
44
Solar Neutrinos
Atoms are mostly empty
space. Squeeze all the
“space” out of the Earth
and it would fit in Scott
Stadium (you would fit in
the head of a pin)
Yes!
NO!
45
Solar Neutrinos
Neutrinos interact weakly even with protons and neutrons.
- When they are produced in the Sun the fly out of the center of the Sun
unimpeded at the speed of light.
–
- A trillion (1012) of them are passing through you every second
right now.
Yes!
46
Solar Neutrinos
Yes!
47
48
Energy Still Leaking out of the Interior

Jupiter as a thermal (infrared) source
49
How Big for Fusion?

Jupiter would have had to have been about 80 times more massive to
get hot enough internally to fuse hydrogen into helium.

We find examples in interstellar space of objects that formed like
stars that didn't reach this threshold – Brown Dwarfs.
50
How Big for Fusion?

Jupiter would have had to have been about 80
times more massive to get hot enough
internally to fuse hydrogen into helium.

We find examples in interstellar space of
objects that formed like stars that didn't
reach this threshold – Brown Dwarfs.
51
Massive Extrasolar Planets


Many of the extrasolar planets being found today are many times the
mass of Jupiter.
Planets this large will still exhibit substantial “leftover” infrared
luminosity.
52
Massive Extrasolar Planets


Many of the extrasolar planets being found today are many times the
mass of Jupiter.
Planets this large will still exhibit substantial “leftover” infrared
luminosity – the younger the brighter – ultimately enabling their direct
detection.
53
Finding Them
54
Finding Them
55
Finding Them