Transcript Chapter 8 Moons, Rings, and Plutoids

Chapter 8
Moons, Rings, and Plutoids
Units of Chapter 8
The Galilean Moons of Jupiter
The Large Moons of Saturn and Neptune
The Medium-Sized Jovian Moons
Planetary Rings
Beyond Neptune
Plutoids and the Kuiper Belt
Summary of Chapter 8
8.1 The Galilean Moons of Jupiter
All four Jovian planets have extensive moon
systems, and more are continually being
discovered.
The Galilean moons of Jupiter are those
observed by Galileo: Io, Europa, Ganymede, and
Callisto.
This image shows Jupiter with two of its Galilean
moons.
The Galilean
moons and their
orbits
Their interiors
Io is the densest of Jupiter’s moons, and the
most geologically active object in the solar
system.
• It has many active volcanoes, some quite
large.
• Io can change surface features in a few
weeks.
• Io has no craters; they fill in too fast – Io has
the youngest surface of any solar system
object.
Io is very close to Jupiter, and
also experiences gravitational
forces from Europa. The tidal
forces are huge, and provide the
energy for the volcanoes.
Europa has no craters;
surface is water ice, possibly
with liquid water below.
Tidal forces stress and crack
ice; water flows, keeping
surface relatively flat.
Ganymede is the largest
moon in the solar
system – larger than
Pluto and Mercury.
It has a history similar
to Earth’s Moon, but
with water ice instead
of lunar rock.
Callisto is similar to Ganymede; no evidence
of plate activity.
8.2 The Large Moons of Saturn and
Neptune
Titan has been known for many years to have an
atmosphere thicker and denser than Earth’s;
mostly nitrogen and argon.
Makes surface
impossible to see; the
picture at right was
taken from only 4000 km
away.
Infrared image of Titan,
showing detail, and
possible icy volcano
Few craters, consistent
with active surface
Complex
chemical
interactions in
atmosphere
The
Huygens
lander took
these
images of
the surface
of Titan.
Trace chemicals in
Titan’s atmosphere
make it chemically
complex.
Triton is in a retrograde orbit;
its surface has few craters,
indicating an active surface.
Nitrogen geysers
have been observed
on Triton,
contributing to the
surface features.
8.3 The Medium-Sized Jovian Moons
Densities of these moons suggest that they are
rock and water ice.
Moons of Saturn, in natural color
Moons of Uranus and Neptune
Miranda shows evidence
of a violent past, although
the origin of the surface
features is unknown.
The only body in the solar
system known to have active
volcanos other than the Earth
is:
A titan.
B callisto.
C Io.
D triton.
The Galilean satellite with
the smoothest surface is
A. Io
B. Europa
C. Ganymede
D. Callisto
The largest satellite (moon) in
our planetary system is
A. Phobos
B. Titan
C. Ganymede
D. The Moon
Io appears more active than the
other Galilean satellites of Jupiter.
this activity may arise from
A. stronger heating of Io due to tidal
friction.
B. the radiation close to Jupiter.
C. Io's smaller density.
D. Jupiter's magnetic field.
Which solar system body is
believed to have deep oceans of
liquid water under a surface of
solid ice?
A. Io
B. Titan
C. Triton
D. Europa
The surfaces of some moons of
Jupiter and Saturn are heavily
cratered. we infer that these
surface regions are
A. regions of volcanic activity.
B. relatively old.
C. relatively young.
D. highland regions
E. .lowland regions.
When a celestial body (like a moon)
comes within the roche limit of a
large body, it
A. will stop rotating.
B. will break apart because of tidal
forces.
C. will fall into the larger body.
D. will be accelerated and ejected.
Which of the moons of the giant
planets is known to have
substantial atmosphere?
A. Callisto
B. Titan
C. Europa
D. Phobos
8.4 Planetary Rings
The ring system
of Saturn is
large and
complex, and
easily seen from
Earth. The other
Jovian planets
have ring
systems as well.
The rings are not solid; they are composed of
small rocky and icy particles.
Our view of Saturn’s
rings changes as the
planets move in their
orbits.
The Roche
limit is where
the tidal
forces of the
planet are too
strong for a
moon to
survive; this
is where
rings are
formed.
All observed ring systems are within this limit.
Voyager probes showed Saturn’s rings to be
much more complex than originally thought.
Earth is shown
on the same
scale as the
rings.
“Shepherd”
moons define the
edges of some of
the rings.
Jupiter has been found to have a small, thin ring.
The rings of
Uranus are
more complex.
Two
shepherd
moons keep
the epsilon
ring from
diffusing.
Neptune has five rings, three narrow and two
wide.
8.5 Beyond Neptune
Pluto was
discovered in
1930. It was
thought to be
needed to
explain
irregularities in
the orbits of
Uranus and
Neptune, but it
turned out that
there were no
such
irregularities.
Pluto’s moon, Charon, was discovered in 1978.
It is orbitally locked to Pluto, and about a sixth
as large.
Pluto also has two smaller
moons, Nix and Hydra,
discovered in 2005.
Charon’s orbit is at a large angle to the plane of
Pluto’s orbit.
8.6 Plutoids and the Kuiper Belt
The first Kuiper belt
objects were observed
in the 1990s, and more
than 700 are now
known. Some of them
are comparable in size
to Pluto.
These images show
Eris and its moon
Dysnomia.
This figure shows several of the largest known
trans-Neptunian objects, now collectively called
plutoids.
The major gaps in the rings of Saturn are most
likely caused by
A. mutual gravitational interactions between
the multitude of particles in the rings.
B. the intervention of a massive body, which
moved through the rings in their early
history, leaving the gaps.
C. combined gravitational forces from Saturn
and its moons, which deviated the paths of
particles which stray into the gaps.
D. the rings were formed in that way, with the
gaps in place.
The rings of Saturn
A. do not contain enough matter to
form a satellite.
B. are too close to the planet to form
a satellite.
C. were not allowed to condense into
a satellite because of the intense
radiation.
D. were stripped from the planet
because of its rapid rotation.
Which of the following characteristics
do the rings of Jupiter, Saturn, and
Uranus have in common?
A. Small particles orbiting the planet.
B. Solid sheets of icy materials.
C. Made of dark, uncoated rocky
particles.
D. Made of light-colored, metallic
particles.
E. Are unstable over short periods of
time.
The ringlets within the ring system
of Saturn are thought to be
maintained by
A. tidal forces from Saturn.
B. solar radiation.
C. shepherd satellites.
D. internal collisions.
Summary of Chapter 8
• Outer solar system has 6 large moons, 12
medium ones, and many smaller ones.
• Titan has a thick atmosphere and may have
flowing rivers of methane.
• Triton has a fractured surface and a retrograde
orbit.
• Medium-sized moons of Saturn and Uranus are
mostly rock and water ice.
• Saturn’s rings are complex, and some are
defined by shepherd moons.
Summary of Chapter 8, cont.
• The Roche limit is the closest a moon can
survive near a planet; inside this limit rings
form instead.
• Jupiter, Uranus, and Neptune all have faint
ring systems.
• Pluto has three moons, Charon, Nix, and
Hydra.
• Dwarf planets beyond Neptune (including
Pluto) are now known as plutoids.