Jovian Planets
Jupiter’s mass
is greater than
all other
planets
combined!
Jovian Planets Basic properties
Jupiter
Saturn
Uranus
Neptune
Semimajor
axis
5.2 AU
9.5 AU
19.2 AU
30.1 AU
Mass (units of
317
90
14
17
11
9
4
4
1.3
0.7
1.3
1.6
H (71%),
He (24%),
5% other
Similar to
Jupiter
H ices, rocks,
H&He
H ices, rocks,
H&He
Earth mass)
Radius (units of
Earh radius)
Density
(gm/cc)
Composition
Very similar to
Solar Values
Large, rock/iron cores, H, He and metalic Hydrogen for Jupiter
and Saturn. Low density. Have many moons, rotate rapidly , and
all have rings
The Solar System
Spacecraft to the Outer Solar System
Flybys: Pioneer 10, 11, Voyager 1, 2
Orbiters/ : Galileo, Cassini
Landers (Jupiter) (Saturn)
Pioneer 10- launch:1972 flyby:1973
Pioneer 11- launch:1973 flyby:1974
Voyager
1- launch:1977 flyby:1979
Voyager 2launch:1977 flyby:1979
Galileo launch:1989 orbit: 1995-2003
Cassini & Huygens probe: launch:1997
orbit: 2004, probe Dec. 2004
Jupiter’s Interior
Molecular
Hydrogen
Metallic
Hydrogen
“Ice”
Rock
Jovian planets radiate extra energy
• Most planets radiate some of the energy
they receive from the Sun
• Jovian planets radiate more energy than
they receive from Sun
• Jovian planets are heated by a mix of
solar heating and extra energy by
gravitational contraction.
318x more massive than
Earth Diameter 11x Earth
Distance 5 A.U.
Gravity = 2.53x Earth
Orbital period ~ 12 Earth
years
Rotation of Jupiter
(9h 50m at
equator, 9h 55m at
poles) fastest of
any planet. This
causes noticeable
oblateness
Jupiter as seen by Cassini
Zones:
Light Bands
High NH3 clouds
Belts
Dark Bands
Clear to lower layers
Great Red Spot
Chaotic pattern
at high latitude
Belts and Zones
convection
Jupiter and Saturn have belts and zones of
clouds, plus circular storms.
Air heated from
above by the
Sun, from
below by
internal heat:
Strong winds and
large storms.
We see clouds of
ammonia
(NH3), colored
compounds.
The Great Red Spot
~ 2 - 3 times
diameter of the
earth.
White = ammonia
clouds
Orange = sulfurcolored ammonia
The Great Red
Spot is a storm that
has been observed
for over 300 years.
Great Red Spot was first seen in 1664!
Jupiter’s Atmosphere
• Spectroscopy from earth and spacecraft reveal
• 86% hydrogen & 13% helium
– traces of other simple compounds
• methane, ammonia, water vapor
Jupiter’s has a wind velocity of 360 km/hr, similar to jet
streams on the Earth
Jupiter has both a liquid
metal core , and fast rotation
which are needed for a
strong magnetic field. So it’s
field is ~14 times stronger
than that of the Earth.
Jupiter’s Rings
• Rings comprised of
small particles of dust
and ice and are darker.
Jupiter Atmospheric Probe Results
• Probe measured temperature, pressure, wind
speed and chemical composition as it descended ~
100km.
• Probe detected
Only heavy clouds
Very dry air
Strong winds >600 km/hr
• Chemical composition
• consistent with solar +
• cometary material
Largest Moons, Smallest Planets
Galilean Satellite Geology
Callisto
• The
image taken by Voyager 2.
•
•The temperature of
Callisto varies from
about 100 K at noon
to 150 K at night.
• Ice was observed
on the surface of
Callisto (by
spectroscopy.
Picture credit: NASA/JPL Voyager 2
Callisto Surface
•The craters are of different shapes compared to those of the
Moon, because at Callisto’s temperature, the ice
is not perfectly solid, and flows very slowly over time.
Ganymede :
largest moon in the solar system
•The large dark
region is about
3200 km in
diameter.
•Parts of this terrain may be
covered
Picture credit:
in aNASA/JPL
bright frost.
Ganymede’s Varied Geology
Two types of terrain are found on Ganymede:
Bright Terrain
Fewer craters,Younger
Dark Terrain
Many craters, Older
Groves caused by expansion of Ganymede’s crust.
Ganymede has a small number of very bright
craters, suggesting that nearly pure water ice
has been ‘splashed’ across the surface by an
impact.
•
•• This
Galileo
•image shows a
crater chain
Picture credit: NASA/JPL Galileo
Europa
Dark Material Seeping
Through Cracks
•Europa is basically a small rocky core,
surrounded by a deep, salty ocean and topped
with a thin water-ice crust.
•The ocean is kept liquid by tidal forces of
Jupiter and nearby moons.
•Europa is the
smoothest
planetary object in
the solar system,
with almost no
impact craters
visible at all.
one of only a few
impact craters on
Europa
Fresh ice oozes
to the surface
through
cracks.
Europa’s magnetic field also suggests a salt-water ocean below the ice.
•The markings are in fact
tectonic cracks produced by
stresses in the crust.
Io: Jupiter’s Volcanic Moon
Io is the most
volcanically active
object in the solar
system, showing
extensive re-surfacing
The pull of Jupiter
causes Io to be pulled
into a elongated shape
(similar to an egg). This
causes enormous
heating.
The next outer moons, Europa and Ganymede also
exert gravitational forces on Io .
Volcanic Plume eruptions can
reach 300 km above the surface.
The Galileo image
(right) shows two
plumes: one on
the limb (130 km
high), and one
erupting from
Prometheus in the
center of the
image.
Surface Colors- The colorful yellows, oranges,
browns and blacks is sulfur, which may form
different colored solid compounds, depending on
how it has cooled.
•
Io’s
gravity
so low
•It is
believed
thatthat
the plumes
plumes reach
occurgreat
whenheights.
a lava
flow meets a deposit of frozen SO2 on the surface.
The SO2 explosively heats up and vaporizes.
•Tidal forces heat the interior. Volcanic plumes
feed a tenuous, patchy atmosphere of SO2 - and S2.
•Escape of 1 ton/second of sulfur and oxygen ions
Jupiter’s magnetic field
makes 3 million amps of
electric currents flows
through IO, producing
intense bursts of radio
emissions.
Saturn
•Composition: Mostly made of
H (70%), He, methane, and
ammonia; Colder than Jupiter,
but hot inside.
Mass = 5.685×1026 kg (92.16 Earths)
Diameter = 120,536 km (9.45 Earths)
Density = 0.687 g/cm³
Sidereal rotation period = 0.449 d (10 h 47 min)
Albedo = 0.47 (Earth = 0.39)
Average distance from Sun = 9.537 A.U.
•General appearance: Cloud belts, wind and
turbulence; Thicker clouds, but clouds are under
methane haze in the top layer, so Saturn is less
colorful than Jupiter.
•Core: It has a larger icy/rocky core than Jupiter.
•Energy: Produces more than it Receives
Saturn could float in water
•Saturn is thought
to have the same
three cloud levels
as Jupiter, but
Saturn is colder.
1.Ammonia cirrus
2.Clouds of
ammonium
hydrosulfide
(NH4SH)
3.Water clouds
Saturn Interior
Molecular
Hydrogen
Metallic
Hydrogen
“Ice”
Rock
Saturn also has a strong eastward jet stream moving at an amazing 1600
km/hr, (1100 mi/hr) extending to 40° either side of the equator.
The Rings disappear, every 16 years, due to the tilt of the
planet.
Saturn’s rings are very thin!
Rings are 270,000,000 meters in diameter and
only 30 meters thick.
Saturn’s rings consist of thousands of narrow,
loosely spaced ringlets, most inside the Roche
limit of Saturn.
Roche Limit: The closest distance from a planet or
object at which a second object can approach
before the tidal forces overwhelms the smaller
object breaking it into smaller pieces, which could
form a ring around the planet.
A rocket ship landing on the Moon holds together,
because of the strength of the materials and the
bolts, or welds holding it together.
Since Saturn's rings lie within the Roche limit, it is
likely that they were either formed by the breakup
of a moon that came too close or particles too close
to Saturn to form a large moon.
Another possibility is that collisions of large moons
outside the Roche limit spewed material into the
region inside the Roche limit.
The ring particles range in size from ‘grain of sand’
size, up to boulders . Small particles of course
greatly outnumber large ones
Gaps in the rings are most likely caused by small
moonlets embedded in the rings.
The tiny moons can also act as shepherd
satellites.They can constrain or shepherd the ring
particles to stay between the moonlet orbits.
Saturn has 7 ring regions, named A through G.
Rings named in order of discovery, not distance
from Saturn, Ring order is: D, C, B, A, F, G, E.
The tiny moon Pan (20 kilometers, or 12 miles across) 0rbits
within the Encke gap and maintains it. Encke- (En-Key)
Potato-shaped Prometheus is seen here, pulling a faint strand
of material away from the ring gravitationally.
Enceladus is a
remarkable object.
Its surface has an
albedo of nearly
100%, the highest
of any object in the
solar system.
•
Enceladus (En-sel a dus)
• This causes the
surface temperature
to be very cold, a
chilly 55 K.
Eruptions of water
vapor from Enceladus probably are the source of
the E ring material. (Fountains of matter)
Titan
Titan has an atmosphere that is more massive
than any terrestrial planet except Venus.
Titan’s atmosphere is largely nitrogen (like the
Earth), with methane and possibly argon as
the most significant minor gases.
Some of Titan’s surface is probably covered
with lakes of methane
January 14, 2005
Rounded boulders 4-15 cm across,
probably frozen water
Rhea
(Re-ah)
Rhea’s density of 1.3 g/cm3 is lower than Titan, Ganymede
Rhea is highly reflective (60% reflection).
Its spectrum shows the features of water ice on the
surface, as we might expect.
Dione
• Dione
(Die-on)
(1120 km) diameter, shows light,
medium and heavily cratered terrain.
The most
interesting
object is the
bright, wispy
material, which
is perhaps
snow extruded
from eruptions
from surface
cracks.
Tethys
(Teth-us)
(1060 km diameter) has
several interesting
surface features.
Visible in the image is
the massive crater 400
km across.
Tethys is also notable
for a huge trench, which
stretches 3/4 of the way
around Tethys.
Tethys
Mimas (No it’s not the Death Star!) (mye-mus)
•The moon Mimas (390 km) has suffered a
very large impact relative to its size: the
crater Herschel is
130 km wide,
10 km deep, and
has a central peak
6 km high! (~4 miles)
The Herschel impact
must have nearly
destroyed this small
moon.
Unusual
(Ep-i-mee –thus)
Janus
Uranus and Neptune
Uranus and Neptune--Interiors
•Uranus and Neptune are very similar sizes: Uranus
is slightly larger, but Neptune is heavier, due to
slightly larger rocky core. ( greater density)
Atmospheres
• Both planets appear green to blue in color. The high, white
clouds we see on Saturn and Jupiter are mostly absent on
Uranus.
• Absorption by methane gives the characteristic blue-green
color.
No distinct features
Blue green
Uranus
Methane clouds and spots
Bluish in color
Neptune
Uranus
Mass = 14.5 Earths, Radius = 4.0 Earths, density =
1.3 x water . Distance: 19.2 AU; Orbital Period: 84
years; Rotation period: 17.2 hours.
•Uranus rotates backwards compared to
most other planets, with a spin axis inclined at 98° to
the plane of the solar system – i.e. it is lying on its
side.
Rings and Moons of Uranus
Neptune
Mass = 17 Earths, Radius = 3.9 Earths,
density = 1.76 x water
Distance: 30 AU; Orbital Period: 163 years;
Rotation period: 16.1 hours.
Clouds and Storms on Neptune
High clouds are made of methane ice crystals. The
heat flow is greater than expected, giving more
storms.
Neptune emits more
heat than it receives .
The conclusion is that
Neptune, being slightly
larger than Uranus, is
still radiating primordial
heat from its formation.
Neptune - The Great Dark Spot and clouds
The Great Dark spot has already disappeared.
Rings
The rings of Uranus and
Neptune are much darker
than Saturn's rings,
reflecting only a few
percent of what little
sunlight reaches them
The rings are also much
narrower than Saturn's
rings.
Ariel
• Ariel
is the brightest
moon of Uranus.
•Shows a surface pockmarked with craters
and criss-crossed with
huge canyons, like
those of Mars.
• The
canyons are
thought to be caused
by down-dropped
fault blocks, due to
expansion of the
moon.
Miranda Surface
• The
surface of Miranda is like a jigsaw puzzle. The
surface shows massive cliffs and valleys 10 to 20
km deep.
•
• One theory is that
the moon was
shattered apart and
fell back together
again multiple
times, exposing
portions of
the core and
burying parts of
the surface.
Triton
(not to be confused with Titan!)
•The mottled surface in the image is called
‘cantaloupe terrain’ due to its appearance.
•Triton is 2,705 km diameter and it orbits Neptune
the ‘wrong way’ - in the opposite sense to the
motion of the planets around the Sun.
• Hence, we suspect
that Triton was
captured by
Neptune’s gravity,
rather than forming
with the planet.
Thanks to the following for allowing me
to use information from their web site :
Nick Stobel
NASA, JPL
The End