Chapter 11: Jupiter
Giant of the Solar System
• Differences
from terrestrial
planets
• Atmosphere
• Structure and
Composition
• Magnetosphere
• Satellites
After completing this chapter,
you should be able to:
• compare the general physical properties of Jupiter/Earth.
• compare orbital and rotational properties of Jupiter/Earth.
• describe atmosphere, hydrosphere, lithosphere,
magnetosphere, and biosphere of Jupiter and
compare to Earth.
• describe Jupiter's cycle of visibility as seen from Earth.
• explain why Jupiter's atmosphere is
so different from Earth's.
• describe Jupiter's ring system.
• describe physical properties/origin of Galilean satellites.
• explain the origin of Io's volcanoes, Europa’s surface.
Jupiter, Saturn,
Uranus, Neptune:
The Jovian Planets
• Outer or giant or jovian planets.
– Over 1400 Earths could fit inside Jupiter
• Composed primarily of lighter ices, liquids, gases.
• Do not have solid surfaces; more like vast, ball-shaped
oceans with much smaller, dense cores at their centers.
• Extensive satellite and ring systems.
Planet Properties:
Relative Mass of Planets
Planet Properties
Average Distance from Sun
Planet Properties:
Planetary Densities
Chemistry of Giant Planets
• Jupiter & Saturn nearly same chemical makeup as Sun.
– primarily hydrogen and helium
– by mass: 75% hydrogen, 25% helium
• Gas compressed in interior until hydrogen liquifies.
• Uranus and Neptune are smaller,
attracted less hydrogen and helium.
• All have interior core composed of rock, metal, and ice;
approximately 10 x mass of Earth.
• Chemistry dominated by hydrogen, oxygen
in form of H2O (water and water ice)
• Reducing chemistry
• Atmospheres hydrogen-based gases:
CH4 (methane) or NH3 (ammonia) or more complex
Jupiter Fact Sheet
•Diameter: 142,800 km (88,736 miles, 11.2 x Earth, 1/10 x Sun)
•Mass: 318 x Earth (~1/1000 x Sun)
•Density: 1.33 g/cm3 (H2O=1, Earth = 5.5)
•Length of Day: 9 hrs 55 min
•Length of year: 12 Earth years
•Average Distance from Sun: 5.2 AU
(483 million miles)
•Tilt of Axis: 3.1o
•Escape Velocity: 60 km/s
•Distance across the Great Red Spot:
40,000 km (~2xEarth’s diameter)
•Temperature at Cloud Tops: 124 K
•Temperature at core: 20,000 K
•Rings: 1, very thin
•Satellites: 28 known
Two Object Solar System?
• The Sun and Jupiter.
• Jupiter has more mass than all of the other objects
in solar system combined.
• Its gravity:
–
–
–
–
moves comets into new orbits,
helps keep asteroids in place,
may have created the Oort Cloud of comets,
controls a system of 28 moons
• Its tidal pull has:
– kept Io molten for billions of years
– probably provided Europa with a deep, liquid ocean
• Its atmosphere has:
– storm swirls larger than the entire Earth
– winds that move at over 400 km/hr faster than interior
View from Earth
• Closest of Jovian
planets to Earth
(~ 4AU at its nearest).
• Fourth brightest object
– brightest when
near opposition
– up to 50” across
• Earth-based telescopes
– distinct, multi-colored bands across surface;
large reddish area in southern hemisphere
– satellites
– intense bursts of radio energy
Viewing Jupiter
• Oppositions occur every 399 days, so Jupiter is
nearest the Earth and brightest once each year.
• Because of its great distance from the Earth, its
brightness does not vary greatly.
• It moves eastward through approximately one
constellation of the zodiac each year, because it
takes just under 12 years to orbit the Sun.
• Jupiter's four large moons (Galilean satellites)
are easily visible through a small telescope
and even binoculars.
• The changing positions of these moons can be
seen during one night's observations.
Rotation Rate
• No solid surface features to observe.
• Cloud features in upper atmosphere move at
different rates, depending on latitude, activity.
– Near equator: 9 hr 50 m period
– Closer to poles: 9 hr 55 m period
(globe)
• Magnetosphere-related radiation
– 9 hr 55 m period
• Observed flattening too small for planet
composed entirely of hydrogen and helium.
Questions
• How do observations of magnetosphere
allow astronomers to measure the
rotation rate of a planet’s interior?
• What is differential rotation?
How is it observed on Jupiter?
• What does Jupiter’s degree of flattening
tell us about its interior?
View from Space
• Pioneer 10 and Pioneer 11 (launched 1972, 1973)
were first spacecraft to visit outer planets.
– navigate asteroid belt
– study charged particles and magnetic field
– photograph “surface”
• Voyager 1 and Voyager 2 launched in 1977.
– Designed to study Jupiter and Saturn; both still
transmitting data as they travel toward boundary
of solar system and into interstellar space.
– Voyager 2 passed
• within 80,000 km of Uranus
(within 16 km of planned target) and
• 5000 km above Neptune’s clouds.
• Galileo launched in 1989; arrived December, 1995.
Voyager Missions
Path through the Solar System
Jupiter Highlights of Voyager Mission
• Found 3 new satellites.
• Io - active volcanism.
• Discovered zones of aurora.
• Discovered rings.
Galileo Project
The Moon, Asteroids, Jupiter, Io, and Europa
• Launched in 1989
from space shuttle
Atlantis.
• Orbiter and
atmospheric probe
Galileo Highlights
• Discovery of an intense new radiation belt approximately 50,000
km (31,000 miles) above Jupiter's cloud tops.
• Jovian wind speeds in excess of 600 km/hr (> 400 mph) detected.
• Far less water was detected in Jupiter's atmosphere than
estimated from earlier Voyager observations and from models of
the Comet Shoemaker-Levy 9 impact.
• Far less lightning activity than anticipated (about 10% of that
found in an equal area on Earth). Individual lightning events,
however, are about ten times stronger on Jupiter than the Earth.
• Helium abundance in Jupiter is very nearly the same as its
abundance in the Sun (24% compared to 25%).
• Extensive resurfacing of Io's surface due to continuing volcanic
activity since the Voyagers flew by in 1979.
• Preliminary data support the tentative identification of intrinsic
magnetic fields for both Io and Ganymede.
• Evidence for liquid water ocean under Europa's surface.
Cassini’s View of Jupiter
• Jupiter in three wavelengths
– left: blue (visible)
– middle: ultraviolet
– right: infrared
Interior Structure
• A rough model of Jupiter's internal structure
can be deduced from the planet's mass,
density, rotation, and shape.
• Jupiter appears to be highly differentiated
with a relatively small rocky and/or metallic
core, perhaps the size of Earth and
with ~10 x Earth’s mass.
Jupiter’s Internal Structure
Structural
Components
% of total
planetary
radius
1 meter =
radius of Jupiter
Cloud layers in upper
atmosphere
0.1
99.9 – 100 cm
Gaseous atmosphere
7
93 – 100 cm
Hydrogen in liquid form
22
71 – 93 cm
Hydrogen in liquid metal
form
57
14 – 71 cm
Rocky, high density core
14
0 – 14 cm
Scaled
Jupiter’s Interior
Jupiter: Composition
• Interior composition:
mostly simple molecules of
hydrogen, liquid form.
• Under the cloud layers,
as the pressure increases,
the hydrogen changes to
liquid hydrogen.
• Further increases in pressure
change liquid hydrogen to
liquid metallic hydrogen.
• Core composition:
heavier,
rocky and
metal
elements.
Jupiter’s Heat Engine
infrared wavelengths
visible wavelengths
Atmospheric motions appear to be driven
by internal and external heating.
Jupiter: Heat Sources
• Atmospheric motions driven by
internal and external heating.
• External
– Solar energy
• Internal
– Primordial heat
generated during formation by collapse of materials onto core.
– Contraction
slow shrinking of planet after formation
• Jupiter radiates about 1.6 times as much
energy into space as it receives from the Sun.
Jupiter’s Internal Motions
• The drawing illustrates a kind of
global motion typical of motions
in both the atmosphere and the
interior of a planet.
• Material rises from warmest
region, and moves in a roiling
motion (like boiling of a pot).
• Shown are three different cells
of activity in the atmosphere
where the air turns over
(depicted by red sheets).
• In the interior of Jupiter,
the liquid layers are warm
enough to move in this fashion.
More on Interior Motions
The drawing shows layered
cylinders of material, in
motion, rolling in different
directions. This pattern may
be in operation with the tips
of cylinders corresponding to
the striped pattern of clouds
seen in the atmosphere.
Questions: Internal Structure
• What is thought to lie beneath Jupiter’s clouds?
– Why do we think this?
• Explain a theory that accounts for the
unexpectedly high temperatures observed at
Jupiter’s cloud tops.
Atmosphere
Atmosphere: Composition
• Jupiter has an extremely dense atmosphere.
• Its composition is more like the Sun
than any of the terrestrial planets.
– Hydrogen - 86%.
– Helium - 13%.
– Methane (CH4) - trace.
– Ammonia (NH3) - trace.
– Water (H2O) - trace.
• Believed that the bulk of the interior has similar
composition.
– This property makes it quite different than the terrestrial
planets and explains its relatively low bulk density.
Jupiter’s Cloud Patterns
• Pattern of clouds in white,
brown, and orange.
• Other shapes include eddy
shapes, white ovals, brown ovals,
and brown barges.
• Eddies and white ovals are
outlined in this picture.
– Form in stripes and move
across face of Jupiter.
– Stripes similar to those found
on all the giant planets.
Cloud Layers of Jupiter
• Three different layers of
clouds or clouddecks.
• Composition of clouddecks.
– 1st: ammonia.
– 2nd: ammonium
hydrosulfide
(ammonia & sulfur)
– 3rd: ordinary water clouds
Atmosphere: Circulation
• Rapid rotation rate causes planet's atmosphere to
– bulge at the equator and
– be flattened at the poles.
• Rotation rate is greater at the equator than
at the poles (differential rotation).
• Jupiter's rapid rotation deflects rising and sinking
currents of gases (Coriolis effect) into
strong zonal flows of winds moving east and west.
– somewhat like super jet streams on Earth.
• The dark belts are bands of sinking, cooler gases,
and the light zones are bands of rising, warmer
gases.
– Equivalent to Earth’s high and low pressure systems.
Global Circulation
Circulation of the Jovian atmosphere. The global circulation
pattern shown here indicates the location and designations of the
belts and zones in Jupiter's cloud layer. (NASA)
Belts
and
Zones
Motions in the Jovian
atmosphere. These drawings
indicate both the horizontal
(left) and vertical (right)
circulation in the clouds of
Jupiter.
(NASA)
Belts and Zones
Wind flow patterns in Jupiter’s belts and zones
Atmosphere: Colors
• Colors are caused by
trace amounts of
organic, sulfur,
and/or hydrogen
molecules which
absorb sunlight at
different wavelengths.
• A great deal of
turbulence occurs at
the interface between
belts and zones.
• These are regions of
large jovian storms.
Storms: The Great Red Spot
The Great Red Spot is thought to be a hurricane which has been
raging on Jupiter for well over 300 years.
High-pressure region with high, cold cloud tops (CCW rotation).
Great Red Spot
Great
Red
Spot
HST images of
Great Red Spot
over a seven
year period.
Storms: White Ovals
Collections of white clouds, grouped together into an oval shape;
commonly found in all regions of Jupiter’s atmosphere.
White Spots vs. GRS
• High pressure storms.
• Compared to Great Red Spot (GRS)
– Lower in the atmosphere than GRS.
– Smaller than GRS.
– Do not last as long as GRS.
Storms: Brown Barges
• Low pressure
storms.
• Lowest in the
atmosphere.
– actually holes
in atmosphere
• Appear around
20oN latitude.
• Short-lived
compared to
GRS
Atmosphere: Origin and Evolution
• Jupiter's atmosphere is thought to be a
remnant of Solar System formation.
• Evolved very little since initial formation.
• That is why planetary scientists feel it is
extremely important to study it.
– It may be somewhat similar to
Earth's primary atmosphere.
Questions: Atmosphere
• Why has Jupiter retained most of its
original atmosphere?
• List some similarities and differences
between Jupiter’s belts, zones, and spots
and weather systems on Earth.
• What is the Great Red Spot?
• What is the cause of the colors in
Jupiter’s atmosphere?
Magnetosphere
• Jupiter has an extensive magnetosphere about
10 time stronger than the Earth's.
• This strong magnetic field is probably caused
by Jupiter's very rapid rotation and its
considerable liquid metallic hydrogen core.
• Its magnetic field extends far out into space in a
sheet structure centered on the plant's equator.
• Jupiter has extremely powerful (and deadly)
radiation belts circling the planet. They are
much more forceful than Earth's.
Jupiter’s Magnetosphere
•Jupiter's magnetosphere is biggest thing in entire solar system.
– Big enough to hold all of Jupiter's moons or Sun itself.
– Tail extends to Saturn.
– From Earth, would appear as large as the full moon.
• High levels of energetic particles trapped in regions of
magnetosphere, similar to Earth’s Van Allen radiation belts.
– New region found by Galileo in uppermost atmosphere
10 x Van Allen in strength.
– Donut-shaped cloud inside the magnetosphere coincides with Io.
•Jupiter lights up with very beautiful aurora. Jupiter also makes
radio signals and other waves (whistler waves, chorus and hiss).
Jupiter’s Magnetosphere
Model of Jupiter’s Magnetosphere
Model of magnetosphere showing
interaction with solar wind and Io torus.
The Io Torus
The Io plasma torus is the result of material being ejected from
Io's volcanoes and swept up by Jupiter's rapidly rotating
magnetic field. Spectroscopic analysis indicates that the torus is
composed primarily of sodium and sulfur atoms.
The Io Torus
Jupiter’s Aurora
• Very powerful energy source.
Produces much more power
(~1,000,000 MWatts) than the
Earth's aurora (~1000 MWatts).
– For comparison, a large city uses about
10,000 MWatts.
• Significantly impacts atmosphere.
• Unlike the Earth, the Jovian aurora
is thought to come from two places:
– from the moon Io, and
– from currents carrying particles
from somewhere deeper in
Jupiter's magnetotail.
Aurora
Jupiter in Radio Wavelengths
View of radio wavelength radiation from particles
trapped in Jupiter’s magnetic field.
Questions: Magnetosphere
• What is responsible for Jupiter’s enormous
magnetic field?
Why is it so much larger than Earth’s?
• How was Jupiter’s magnetic field discovered?
• Compare Jupiter’s magnetic field to Earth’s
magnetic field.
– Include generation, field strength, aurora, trapped
particles, interaction with moons.
Hydrosphere
• Near the top of Jupiter's atmosphere, water is
frozen, but below the cloud tops the
temperature and pressure gradually change
increase.
• There is probably a level at which liquid water
is stable.
• There should be a fair amount of water in the
jovian atmosphere.
• Results from the Galileo atmospheric probe
indicated less water than predicted. These
results are still being analyzed.
Biosphere
• Of course, none is known, but some have
speculated about the possibility of life
existing at hospitable levels in the jovian
atmosphere.
• However, strong down drafts are likely to
destroy fragile organic compounds soon
after they form.
Jupiter’s Moons
Transits of Jupiter’s Moons
The Moons of
Jupiter
•28 known moons
– 4 very small moons orbiting
< 3.1 x radius of Jupiter
– 4 large “Galilean” moons
– 8 small moons
• 4 in eccentric, inclined orbits,
~11 million km from Jupiter
• 4 in eccentric, retrograde orbits,
~22 million km from Jupiter
– 12 recently discovered small moons in inclined, eccentric,
mainly retrograde orbits, 10-25 million km from Jupiter
Jupiter’s Moons
• Jupiter has 28 known moons.
• Most are rather small, but the four largest
(discovered by Galileo in 1609) are as large or
larger than the Earth's Moon.
• The largest (Ganymede) is larger than the
planets Mercury and Pluto.
• The comparative features of the Galilean
Moons mimic to some extent the properties of
the planets in the Solar System.
• The jovian satellite system is itself somewhat
like a miniature solar system.
Jupiter’s “Galilean Satellites”
• Io, Europa, Ganymede, Callisto comparable in
size to Earth’s Moon, move in nearly circular
orbits about Jupiter.
• System similar to scaled-down solar system,
– as distance from Jupiter increases, moons’ sizes
increase and moons’ densities decrease,
• Jupiter’s rotation slowing due to tidal drag of
Galilean satellites, and satellites’ orbits slowly
increasing.
• Io, Europa, and Gandymede locked in a 1:2:4
orbital resonance; Callisto approaching 2x period
of Gandymede. (1:2:4:8)
The Galilean Satellites
These are the
four moons
discovered by
Galileo, shown in
correct relative
size. Ganymede is
the largest
satellite in the
solar system..
(NASA)
Galilean Moons
Galilean Moon
Facts
Distance
Orbital
Diameter
from Jupiter
period
(km)
(days)
(km)
Io
422,000
3640
1.77
Europa
671,000
3130
3.55
Ganymede
1,070,000
5270
7.15
Callissto
1,880,000
4800
16.7
Galilean Moons
in Cross-Section
Core
Mantle
Crust
Io
Iron/iron sulfide
Rocky
Young, thin,
volcanic
Europa
Iron/iron sulfide
Rocky
Thin?, water/ice
Ganymede Iron/iron sulfide
Rocky
Thick, icy
Callisto
Ice/rock
Io
Io
Io
• Innermost Galilean satellite.
• Composition is mostly rocky,
almost no volatiles.
• Driest place in the outer Solar System.
• No impact craters, surface renewed to 300 feet
every million years.
• Surface composition is sulfur lava and SO2.
• Active volcanoes erupting sulfur, SO2, and
sodium compounds.
• Extremely violent eruptions are 10 x greater than
Earth's.
• Volcanoes eject matter into Jupiter's magnetic
field and radiation belts (10,000 tons/second).
Volcanic Activity on Io
• Source of geological activity
on Io is tidal effect of Jupiter
on Io as it orbits the giant
planet.
• These tidal forces are so large
that Io's surface is pulled
upwards and downwards by
hundreds of meters in each
rotation.
• Tidal squeezing causes the
interior to melt, causing
volcanic activity.
• Heat flow is 30 times greater
than Earth's.
• A very thin (10-7 Earth's)
atmosphere of SO2.
Volcanic Vents on Io
Recent Volcanic Activity on Io
Io Torus
• The following series of photographs, taken through a
ground-based telescope on Earth, shows the cloud of
sodium atoms surrounding Io as it orbits Jupiter.
• The yellow color of the cloud is due to the fact that
sodium atoms emit most strongly in a pair of emission
lines in the yellow part of the spectrum.
• Once this gas, which also includes other atoms such as
sulfur, escapes from Io, it becomes ionized and then is
spread all the way around Io's orbit by magnetic forces.
• This ionized gas is not visible here, so we do not see the
full extent of the torus.
• The sizes of Jupiter, Io (dot inside the cross-hair), and Io's
orbit are all to correct relative scale.
• (B. A. Goldberg, G. W. Garneau, and S.K. LaVoie, JPL)
Io Torus
Ground-based
telescope on Earth,
shows the cloud of
sodium atoms
surrounding Io as it
orbits Jupiter.
The sizes of Jupiter, Io
(dot inside the crosshair), and Io's orbit
are all to correct
relative scale.
(B. A. Goldberg, G. W.
Garneau, and S.K.
LaVoie, JPL)
Three Icy Moons
Callisto
Ganymede
Europa
Europa
Europa
• Young smooth surface with
very few craters.
• Perhaps an icy surface and
a rocky interior.
• Cracks are observed as
ridges of fresh ice on the
surface.
• May be an ocean of liquid
water below the icy
surface.
• A thin atmosphere of
oxygen was detected by
Galileo spacecraft.
Europa’s Surface: A Close-up View
Surface of Europa
• The blue hues represent ice plains divided by dirty red and brown
bands of terrain. The dark color may represent organic matter.
• The cause for many of the cracks remains unknown but may
involve shifting stresses from gravity and temperature variations.
Europa’s Evolution
• Europa, like Io, is heated internally
by the tidal tug-of-war with Jupiter.
• Since Europa is further from
Jupiter than Io,
the tidal effect is less dramatic.
• In the case of Europa, the effect of
the tides induced by Jupiter is to
heat the interior of Europa
sufficiently to keep the surface soft.
• Thus, no vertical relief features can
survive for long on Europa's
surface, explaining its smooth
appearance.
Europa--Surface and Interior
Ganymede
Ganymede
• Largest satellite in the
Solar System.
• Composed of a mixture of rock
and water ice.
• Probably a very thick crust of
water ice.
• It has a combination of cratered
and grooved terrain.
• Changing ice phases may have
caused it to expand 3.5 billion
years ago forming grooves and
ridges.
Moon Size
Ganymede’s Features
•
•
•
•
•
Largest moon in the Solar System (larger than Mercury).
Largely covered by a frozen water ocean.
Portions of surface look young geologically; portions look old.
Large grooves in surface; crust broken into fragments.
Evidence for past plate tectonic activity; first conclusive
evidence of plate tectonics in the Solar System beyond the Earth.
• Weak magnetic field,
first detected for
satellite in this Solar
System.
Ganymede-Surface Features
Tectonic features
New and Old Terrain
Crater Basin
Ganymede’s Interior
Callisto
Callisto
• Outermost of the Galilean Satellites.
• Very old surface, covered with craters and
impact basins.
• Lowest density of the large moons.
• Composed of perhaps 50% water ice.
• Shows the least amount of tectonic activity.
• It may have some internal differentiation
caused by radioactive decay.
Callisto’s Cratered Surface
•Callisto has the most
heavily cratered
surface of the four
Galilean moons.
•The number of craters
imply that the surface
of Callisto is
~ 4 billion years old.
Callisto’s Surface
• Similar in appearance to Ganymede,
more craters and fewer fault lines.
• Most obvious feature: huge series of
concentric ridges surrounding two
large basins.
• Ridges resulted from impact with
asteroid or comet. Up-thrust ice
partially melted; resolidified quickly,
before the ripples subsided.
• Today, ridges and rest of crust are
frigid ice, showing no obvious signs of
geological activity.
• The density of impact craters on the
Valhalla basin indicates that it
formed ~ 4 billion years ago.
Valhalla Impact Basin
Comparison of Galilean Satellites
MOON
WATER
DENSITY
ACTIVITY
CONTENT
Io
highest
least
greatest
Europa
2nd
2nd
2nd
Ganymede
3rd
3rd
3rd
Callisto
lowest
most
least
Questions: Moons
• Compare sizes of Galilean moons terrestrial objects.
• Describe the variation in density as a function of
distance from Jupiter for the Galilean moons.
• How does the amount of cratering vary among the
Galilean moons? Does it depend on their location?
If so, how?
• What is the source of all the activity observed on
Jupiter’s Galilean satellites?
• Why is there speculation that the Galilean moon
Europa might be an abode for life?
• Water is relatively uncommon among the terrestrial
planets. Is it common among the moons of Jupiter?
Jupiter’s Ring
Discovered in 1979 by Voyager missions; inside orbit of innermost
moon; few 1000 km across, few 10’s km thick; in equatorial plane;
made of small grains of rocky material, albedo ~0.05, no ice.
Questions: Rings
• How was Jupiter’s ring discovered?
• Describe the ring:
– location,
– particle size range,
– particle density,
– particle color,
– source of ring material.
Jupiter
•
•
•
•
•
Largest planet in the solar system.
Primarily composed of hydrogen and helium.
Rapid, differential rotation.
Internal structure and heat source.
Thick atmosphere with 3 main cloud layers.
– Layers arranged into bands of bright zones and darker belts
that cross surface parallel to equator and are the result of
convection and rapid planetary rotation.
– Stable zonal E-W wind flow underlying belts/zones.
– Long term weather patterns/storms:
Great Red Spot, white ovals, brown ovals.
• Magnetosphere
• 28 known satellites
– Galilean satellites
• Small, dark, faint rings; discovered by Voyager 1.
Overview of Jupiter from Earth
• Jupiter is a giant planet located fifth from Sun.
– It’s mass of 318 x Earth’s and diameter of 11 Earth
diameters yield an average density of 1.3 x water.
• It appears through ground-based telescopes as a gas
giant flattened by rapid rotation, with reddish and
whitish belts and zones. Within one zone in
S-hemisphere is the Giant Red Spot (~2xEarth). Many
satellites visible; four largest called Galilean satellites.
• Ground-based radio telescopes found synchrotron
radiation, indicating the presence of a strong magnetic
field.
• Other observations show that Jupiter emits 2x energy
it captures from Sun. Excess energy from internal heat
from time of Jupiter’s formation.
Overview of Jupiter from Space
• Pioneer and Voyager probes show highly turbulent,
stormy atmosphere, lightning, and aurorae.
• Confirmed expected presence of hydrogen and
helium as the main constituents of the planet.
–Atmosphere: hydrogen, helium, ammonia, methane
• Voyager discovered a ring composed of small, dark,
rocky grains.
• Magnetosphere mapped: extensive and tilted 100 to
rotation axis.
• Interior structure modeled as a rocky core
surrounded by a region of liquid metallic hydrogen.
Believed that this material behaves like a metal and
that its rotational and turbulent convection motions
produce the planet’s magnetic field.
Overview of Jupiter’s Moons
•28 known satellites
•Four largest, called the Galilean satellites, form a “miniature
solar system” around Jupiter .
–Io
•volcanic
•gases form a cloud around Io and its orbit; creates aurora torus
–Europa
•straight-line features in icy methane and ammonia surface
•possible water ocean beneath surface
–Ganymede
•largest satellite in solar system, first observed with magnetic field.
•cratered, icy crust with evidence past plate tectonics activity
•Possible water ocean beneath surface
–Callisto
•old, icy, saturated with craters and a large multi-ringed basin