Transcript Jupiter - Stockton University

Jupiter
Jupiter
Largest and most massive
planet in the solar system
Contains almost ¾ of all
planetary matter in the solar
system.
Most striking features visible
from Earth: Multi-colored
cloud belts
Explored in detail by
several space probes:
Visual image
Infrared falsecolor image
Pioneer 10,
Pioneer 11,
Voyager 1,
Voyager 2,
Galileo
Exploration of Jupiter
Previous Missions
Pioneer 10 & 11
Voyager 1 & 2
Latest Jupiter Mission
Galileo (1995 - 2003)
Galileo Probe
What did it tell us?
What did we expect?
Jupiter’s Rotation
Jupiter is the most
rapidly rotating
planet in the solar
system
Rotation period
slightly less than 10
hr.
Centrifugal forces
stretch Jupiter into a
markedly oblate
shape.
Jupiter’s Atmosphere
Jupiter’s liquid hydrogen
ocean has no surface:
Gradual transition from
gaseous to liquid phases.
Only very thin atmosphere
above cloud layers;
transition to liquid hydrogen
zone ~ 1000 km below clouds.
Jupiter’s Cloud layers
•
•
•
•
Haze (at the top)
Ammonia
Ammonium Hydrosulfide
Water (lowest observed layer)
What did the Probe find?
At depth of 1 bar (Earth Sea level):
T = 130 K (-225 F), P=1 bar
Survived to a depth of 150 km:
T = 425 K (305 F), P=22 bars
Hotter and denser than expected
Ammonia and water layers were not detected
Wind velocities much greater (435 mph)
Chemically like Sun in terms of H, He, but a bit
off in other elements
Jupiter’s Atmosphere
Three
layers of
clouds:
1. Ammonia
(NH3)
crystals
2. Ammonia
hydrosulfide
(NH4SH)
3. Water
crystals
Heating mostly from
latent, internal heat
Observations of Jupiter from the Earth
reveal clouds and atmospheric structures
Belts
Zones
The Cloud Belts of Jupiter
Dark belts and bright zones.
Zones higher and cooler than belts;
high-pressure regions of rising gas.
The Cloud Belts on Jupiter
Just like on Earth, high-and low-pressure zones
are bounded by high-pressure winds.
Jupiter’s Cloud belt structure has remained
unchanged since humans began mapping them.
Clouds, clouds, clouds
Rotation rate is about 10 hours
Differential Rotation (different parts rotate at different rates)
Produces turbulence, and storms
© Calvin Hamilton
The Great Red Spot
Has been visible
for over 400
years
Giant storm system
similar to
Hurricanes on
Earth: Wind speeds
of 430 km/h (= 270
miles/h)
Changes appearance
gradually over time
8-year sequence of
images of the
Great Red Spot on
Jupiter
The Great Red Spot
A storm that has been
going on for nearly 400
years
2-3 x size of the Earth
The History of Jupiter
Formed from cold gas in
the outer solar nebula,
where ices were able to
condense.
In the interior, hydrogen
becomes metallic (very good
electrical conductor)
Rapid growth
Rapid rotation → strong
magnetic field
Soon able to trap gas
directly through
gravity
Rapid rotation and large
size → belt-zone cloud
pattern
Heavy materials sink
to the center
Dust from meteorite impacts
onto inner moons trapped to
form ring
Jupiter’s Magnetic Field
Magnetic field at least 10 times stronger than Earth’s magnetic
field.
Magnetosphere over 100 times larger than Earth’s magnetosphere
Aurorae on Jupiter
Just like on
Earth, Jupiter’s
magnetosphere
produces aurorae
concentrated in
rings around the
magnetic poles.
~ 1000 times
more powerful
than aurorae
on Earth.
Particles producing
the aurorae
originate mostly
from moon Io
Aurora requires a
magnetic field
What’s Jupiter’s
magnetic field like?
How is it produced?
Rock and
Metal
Liquid Metallic
Hydrogen
Liquid
Molecular
Hydrogen Hydrogen
Jupiter’s Ring
System
Jupiter’s Ring
Not only Saturn, but all four gas giants have rings.
Galileo spacecraft
image of Jupiter’s
ring, illuminated
from behind
Jupiter’s ring: dark
and reddish; only
discovered by
Voyager 1
spacecraft.
Composed of microscopic
particles of rocky material
Location: Inside Roche limit, where larger bodies (moons)
would be destroyed by tidal forces.
Satellites of Jupiter
Currently 60+ known satellites - most
Most small asteroid-like, only a few km in size
4 largest satellites are the Galilean Satellites
Io, Europa, Ganymede, Callisto
The
Galilean
Satellites
Io - The Volcanic World
Io: Bursting Energy
Most active of all Galilean moons; no impact craters visible at all.
Over 100 active
volcanoes!
Activity powered
by tidal
interactions with
Jupiter.
Interior is
mostly rock.
Surface features have changed since the Voyager
spacecraft visited (1979) and the Galileo
spacecraft’s observations (late 1990’s)
Continual volcanic eruptions
Why?
Io has the highest density
Io has the fewest craters - youngest surface
Io is closest to Jupiter
And on the other side are the other 3 large
satellites
Io is a victim of a tug of war (tidal heating)
due to Jupiter and the other moons!
Jupiter’s Influence on its Moons
Presence of Jupiter has at least two
effects on geology of its moons:
1. Tidal
effects:
possible
source of
heat for
interior of
Ganymede
2. Focusing of
meteoroids,
exposing
nearby
satellites to
more impacts
than those
further out.
Interactions with Jupiter’s Magnetosphere
Io’s volcanoes blow out sulfur-rich gases
→ tenuous atmosphere, but gases can not be retained by Io’s
gravity
→ gases escape from Io
and form an ion torus in
Jupiter’s magnetosphere.
→ Aurorae on Jupiter are
fueled by particles from
Io
Europa - The Ice World
Europa: A Hidden Ocean
Close to Jupiter → should be
hit by many meteoroid
impacts; but few craters
visible.
→ Active surface; impact
craters rapidly erased.
The Surface of Europa
Cracked surface and high albedo (reflectivity)
provide further evidence for geological activity.
Ice features that are slowly changing
Very few craters
Lower density than Io
Slightly older surface
The Interior of Europa
Europa is too small to retain its internal heat → Heating mostly from
tidal interaction with Jupiter.
Europa has a
liquid water
ocean ~ 15
km below the
icy surface.
Ganymede - The Largest Moon
Ganymede: A Hidden Past
Largest of the 4 Galilean moons.
Rocky core
Ice-rich mantle
Crust of ice
1/3 of surface old, dark,
cratered;
rest: bright, young,
grooved terrain
Bright terrain probably
formed through flooding
when surface broke
Light and
Dark
Terrain
indicates
some
resurfacing
Lower Density
More craters, Less resurfacing
Older surface than Europa
Callisto - The Cratered Moon
Callisto: The Ancient Face
Tidally locked to Jupiter, like all of Jupiter’s moons.
Composition: mixture of
ice and rocks
Dark surface, heavily
pocked with craters.
No metallic core:
Callisto never
differentiated to form
core and mantle.
→ No magnetic field.
Layer of liquid water, ~ 10 km thick, ~ 100 km below surface,
probably heated by radioactive decay.
Valhalla Impact Basin - rings extend out 1500 km
Lowest Density
Most craters
Very little
resurfacing
Oldest surface