Lecture Slides
CHAPTER 8: The Giant Planets
Understanding Our Universe
SECOND EDITION
Stacy Palen, Laura Kay, Brad Smith, and George Blumenthal
Prepared by Lisa M. Will,
San Diego City College
Copyright © 2015, W. W. Norton & Company
The Giant Planets
 We will learn how the
giant planets are
different from the
terrestrial planets.
 We will learn the
similarities and
differences between
the giant planets
themselves.
Comparative Planetology
Comparative Planetology:
Physical Properties of the Giant Planets
 Jupiter and Saturn: easily seen by naked eye.
 Uranus (1781) and Neptune (1846) were discovered
after invention of telescope.
 These worlds are all larger and more massive than
the terrestrial planets.
 Their orbits span a large distance: 5-30 AU.
 Called “giant planets” because of their mass (15 - 318
Earth masses) and also their physical size (4-11 Earth
radii).
Properties of the Giant Planets
 Astronomers determine diameters by observing how
long it takes for a planet to pass over a star: stellar
occultation.
 Masses can be found by gravitational effects
(Kepler’s laws!) on moons and planetary spacecraft.
Properties of the Giant Planets: Gas and Ice Giants
 Jupiter and Saturn are primarily hydrogen and
helium - gas giants.
 Uranus and Neptune contain more water ice and
other ices than Jupiter and Saturn - ice giants.
 No solid surfaces: we just see the cloud layers in
the atmospheres.
Properties of the Giant Planets:
Composition and Comparison
 The giant planets are less dense than the terrestrial
planets—in fact, Saturn would float in a large enough
vat of water.
 Jupiter’s chemistry is like the Sun: mostly hydrogen
and helium.
 Saturn has more heavy elements than Jupiter.
 Uranus and Neptune have a significantly larger
fraction of massive elements in their composition than
either Saturn or Jupiter.
Properties of the Giant Planets: Axial Tilt
 All giants have
rapid rotation.
 Each as a different
axial tilt, ranging
from:
• Jupiter: 3°,
effectively no
seasonal variation
• Uranus: 98°, which
results in extreme
seasons.
Jupiter: Properties
 Jupiter: strong dark bands (belts) and light bands
(zones).
 A long-lasting giant storm (Great Red Spot).
 Many smaller storms.
 Complex behavior including “cloud cannibalism.”
 The colors of the bands on Jupiter are determined by
their chemical composition.
Jupiter: Properties (Cont.)
Jupiter: Properties (Cont.)
Jupiter: Properties (Cont.)
Jupiter: Properties (Cont.)
Jupiter: Properties (Cont.)
 The colors of the bands on
Jupiter are determined by
their chemical composition.
Saturn: Properties
 Has lightningproducing storms, as
well as a strong wind
pattern similar to
Earth’s jet stream.
 Saturn: similar band
structure to Jupiter, but
less obvious.
 The cloud layers on
Saturn are thicker than
Jupiter because of the
lower gravity of Saturn.
Saturn: Properties (Cont.)
Saturn: Properties (Cont.)
Saturn: Properties (Cont.)
 Saturn: similar band
structure to Jupiter, but
less obvious.
 The cloud layers on Saturn
are thicker than Jupiter
because of the lower gravity
of Saturn.
Uranus & Neptune
 Uranus and Neptune: infrared observations show
weak patterns of bands.
 Small, scattered bright or dark clouds.
 Transient large storms (Great Dark Spot on Neptune).
Uranus & Neptune (Cont.)
Uranus & Neptune (Cont.)
Uranus & Neptune: Presence of Methane
 Highest clouds on Uranus and
Neptune: methane ice.
 Bluish-green color because of
presence of methane in their
atmospheres (methane
absorbs red, orange, yellow).
Properties of the Giant Planets: Wind Speeds
 Rapid planetary rotation results in strong Coriolis
forces, giving storms a rotation.
 Most extreme winds are in Saturn’s atmosphere
(1,690 km/hr).
Properties of the Giant Planets: Circulation Patterns
 The alternating east/west winds make the prominent
banded cloud pattern on Jupiter.
 Circulation patterns differ from planet to planet for
reasons not yet understood.
Properties of the Giant Planets: Depths and Pressure
Jupiter/Saturn:
 At depths of a few 1,000 km, gases are compressed
so much they liquefy.
 At higher pressure and temperature, this liquid
hydrogen can act like a metal.
Properties of the Giant Planets: Composition
Uranus/Neptune:
 Have much less hydrogen and helium.
 Have more water and ices (ammonia, methane).
Properties of the Giant Planets: Cores
 All four giant planets have large, dense “rocky” cores.
 The cores are molten, because of the very high
temperatures and pressures.
Properties of the Giant Planets: Magnetic Fields
 Strong magnetic
fields are generated
by the motion of the
conducting liquids.
=>Stronger than
those of the
terrestrial planets.
 The shapes of the
magnetic field are
similar to that of a
bar magnet.
Properties of the Giant Planets: Magnetic Fields (Cont.)
Properties of the Giant Planets: Magnetic Fields (Cont.)
Properties of the Giant Planets: Magnetic Fields (Cont.)
Properties of the Giant Planets: Magnetic Fields (Cont.)
Properties of the Giant Planets: Magnetospheres




Magnetospheres are huge.
They interact with the solar wind.
Create radiation belts and auroras.
Emit radio waves.
Rings
 All four gas giants
have ring systems.
 The rings are
composed of
countless tiny
particles.
 Ring particles orbit
their planet following
Kepler’s laws.
Rings: Shepherd Moons
 The rings are
influenced and
maintained by
shepherd moons.
 Particles most likely
came from moons
disrupted by tidal
stresses.
Rings: Shepherd Moons (Cont.)
Rings: Shepherd Moons (Cont.)
Rings: Shepherd Moons (Cont.)
Rings: Shepherd Moons (Cont.)
Rings: Ringlets
 Saturn has the most
complex rings.
 A very complicated
system, composed
of thousands
of ringlets.
 There are bright and
dark rings, “gaps,”
and divisions.
Rings: Facts
 Gaps are not
empty.
 Brightness/darknes
s reflects the
amount of material
in each ring.
 Though wide, the
ring system is
extremely thin.
Rings: Ring Arcs
 The other giants’ rings
are mostly narrow
and diffuse.
 Backlighting brings
them into view.
 Neptune has denser
sections known as
ring arcs.
Rings: Ring Arcs (Cont.)
Rings: Ring Arcs (Cont.)
Rings: Visual Comparison
 Saturn: bright rings because they are made of mostly
water ice.
 Uranus and Neptune: dark rings from organic material
(darker than coal).
 Jupiter: not as dark as the ice giants, nor as bright as
Saturn’s, likely composed of silicates, and possibly
caused by asteroid collisions with one or more moons.
 Volcanism on moons can also contribute ring material.
Rings: Lifespan
 Rings do not last
forever.
 Collisions and
sunlight destroy the
rings.
 Shepherd moons
can help stabilize
the rings.
Class Question
If you could measure the velocities of ring particles
at each distance from Saturn, you would find:
A. Particles closer to Saturn orbit at slower
speeds.
B. Particles farther from Saturn orbit at slower
speeds.
C. Orbital speed is the same at all distances.
Class Question
Which of the following statements about the giant
planets compared to terrestrial planets is correct?
A. The giant planets have more mass and
higher densities.
B. The giant planets have larger radii and
weaker magnetic fields.
C. The giant planets have more mass, larger
radii, lower densities, and stronger magnetic
fields.
D. The giant planets and terrestrial planets
have overall similar characteristics.
Chapter Summary
 The giant planets are larger and less dense than the
terrestrial planets and consist primarily of light
elements rather than rock.
 Temperatures and pressures in the cores of the giant
planets are very high.
 All four giant planets have ring systems.
Nebraska Applet
Planetary Formation Temperatures Plot
Click the image to launch the Nebraska Applet
(Requires an active Internet connection)
Nebraska Applet
Solar System Properties Explorer
Click the image to launch the Nebraska Applet
(Requires an active Internet connection)
Nebraska Applet
Planetary Orbit Simulator
Click the image to launch the Nebraska Applet
(Requires an active Internet connection)
Understanding Our Universe
SECOND EDITION
Stacy Palen, Laura Kay, Brad Smith, and George Blumenthal
Prepared by Lisa M. Will,
San Diego City College
This concludes the Lecture slides for
CHAPTER 8:
The Giant Planets
wwnpag.es/uou2
Copyright © 2015, W. W. Norton & Company