Download Jupiter and Its Moons Jupiter`s Atmosphere

Jupiter and Its Moons
History and Interior of Jupiter
• Accreted as gas
giant (H2, He)
• Gaseous atmosphere,
underlain by liquid, Trace compounds
Fluid molecular
with small core
Hydrogen
• Interior heat
Transition zone
generated by
Fluid metallic
hydrogen
gravitational
Possible core
collapse?
Cloud tops — aerosols
Ammonia crystals
Ammonium hydroxide clouds
Ice crystal clouds
Water droplets
20Mm
40Mm
60Mm
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Jupiter’s Atmosphere
Various Prominent Banded Features
• Pronounced zonal winds, eddies
• White ovals, brown
blebs, streaks, bands
• Great Red Spot
• cyclonic feature
Great Red Spot
white ovals
Brown blebs
Great Red
Spot
eddies
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Jupiter’s Gravity
Comet Shoemaker-Levy 9
• Broken into fragments by
Jupiter’s gravity in 1992
• Each fragment impacted
Jupiter’s surface in 1994
Impact of Fragment G
• Chains of
Jul 18 1994
impacts
also
observed
on moons
Jupiter
and Comet
Shoemaker
-Levy 9
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Jupiter’s Moons
17 Moons and a Ring System
• Range of Distances, Sizes, and Orbital Periods:
• 128 - 24,200 x 103 km (Moon = 384)
• 20km - 5,276km (Moon = 3476km)
• 0.3 - 774 days (proportional to distance)
• Galilean satellites:
Callisto
Name
Size
(km)
Distance
(103 km)
Callisto
Europa
Ganymede
Io
4,880
3,126
5,276
3,629
1,883
671
1,070
422
Ganymede
Europa
Io
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Jupiter’s Moons: Io
History and Features of Io
• Heated by tidal forcing
sulfur,
rock
mantle
• caused loss of icy mantle?
• Volcanically active
• Density: ~3.5g/cm3
• Atmosphere:
Fe, rock
core
• 90% sulfur
• Composition:
• silicates
• sulfur
• iron
volcano
and lava
plain
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Jupiter’s Moons: Europa
Features of Europa
cracked
surface
• Ice crust with cracks
•
•
•
•
• stressed and heated by tidal forcing
• evidence of ice volcanism
• ice movement in plates?
Rocky interior and core
Density: ~3.0g/cm3
No atmosphere
Liquid water below ice
surface?
• viable environment for life?
• focus for astrobiological studies
refrozen
ice flows
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Jupiter’s Moons: Ganymede
History of Ganymede
ice crust
• Surface features
metallic core
• older cratered dark regions (40%)
• younger light grooved terrain from
faulting and water release (60%)
• Metallic core (400-1500km)
grooved terrain
• Density: ~1.9g/cm3
water/ice
mantle
cratered
dark region
tectonic
features
old terrain
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Jupiter’s Moons: Callisto
History of Callisto
• Geologically inactive
• crust frozen at formation
• highly cratered (maximal density)
• no signs of tectonism
• Interior
• partially differentiated?
• or homogeneous, never molten
• low abundance of radioactive
isotopes
• little tidal forcing
• Density: ~1.9g/cm3
• mixture of rock and ice
Valhalla
crater
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Galilean Moons: Comparisons
Io
Europa
Ganymede
Callisto
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Saturn, Its Moons and Rings
History and Interior of Saturn
• Accreted as gas
giant (H2, He)
• Gaseous atmosphere,
with interior largely
liquid, plus small core
and mantle
• Interior radiates heat from
internal heat source
(gravitational collapse?)
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Interior of Saturn
Characteristics of Core
Possible
composition
of interior
• Formed by accretion and
gravitational collapse?
• Iron core surrounded by liquid H2
and ice?
Sequential formation of core by aggregation and separation
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Features of Saturn
General Characteristics and Surface
• Low density (0.7 g/cm3)
• Fast rotation (10-11 hours)
• Bands, anticyclones, storms
around great white spot
• High velocity winds (up to
1800 km/hr?)
• Aurora in
upper
atmosphere
anticyclone
(size of
Earth)
aurora
white spot
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Saturn’s
Atmosphere
auroras
250
tropopause
200
Layered Structure
haze layers
0.5
visible cloud tops
altitude (km)
150
NH3 ice?
1
100
pressure (bar)
• Aurora in upper
atmosphere
• Ammonia (NH3)
• Ammonium hydrosulfide (NH4HS)
• Water (H20)
• Liquid layers below
(H2, He, CH4,
NH3, H20)
0.1
NH4HS ice?
50
Troposphere
H2, He, CH4, NH3, H2O
10
H2O ice?
0
H2O fog?
0
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200
400
600
800
temperature (K)
Saturn’s Rings
Five Major Components
• G, F, A, B and C rings, with
innumerable ringlets
• Cassini division between A, B
• Composed of particles, mainly
ice crystals
spokes
major ring and ringlets
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Saturn’s Moons
General Characteristics
• 19 moons named, most are icy (densities 1-1.5
g/cm3), but may have rocky constituents, cratered
• Many are locked by tidal forces.
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Saturn’s Moon Titan
Characteristics
• Opaque atmosphere with
several layers of haze
• Primary liquid N2, with 1%
CH4
• Thick smog composed of
hydrocarbons?
• Oceans of CH4, ethane (C2H6)
• Surface temperature -180°C
Titan
Variations in
Titan’s surface
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Saturn’s Moons
Major Moons
Tethys
• Icy surfaces, with impact craters
• Mimas impact ~25% of diameter
• Some ‘shepherd moons’ stabilize rings
Rhea
Mimas
Iapetus
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Uranus
Major Characteristics
• Discovered in 1781 by Herschel
• Gas giant: hydrogen and helium
(1.2g/cm3), also heavier elements
• Rotational axis 8°off orbital plane
• Rings (> 5, rock not ice?) and
many moons (5 major, 10 smaller),
some may be ‘shepherd moons’
• Methane (gives blue color), ethane,
acetylene, diacetylene in
atmosphere. Surface is -210°C
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Uranus’s Icy Moons
Shakespherian Names
• Miranda, Ariel, Umbriel, Oberon,
Titania, Ophelia, Bianca, Cressida,
Desdemona, Juliet, Portia,
Rosalind, Belinda, Puck, Caliban,
Sycorax, Prospero, Setebos,
Stephano
Oberon
Miranda is geologically
active: tidal forcing?
Miranda
Ariel
Umbriel
Titania
Oberon
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Neptune
Major Characteristics
• Discovered in 1845
• Gas giant: H2, He (1.6g/cm3),
also heavier elements
• Internal heat source
• Methane (gives blue color) in
atmosphere. Surface is -216°C
• ‘Great dark spot’ long-lived storm
system; winds 1000 km/hr.
• Faint rings (dust grains?) and two
large moons; weak magnetic field
Great dark spot
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Neptune’s Moons
Triton and Nepeid
• Triton: comparable in size to Earth’s Moon
• Retrograde motion around Neptune (captured?)
• Thin atmosphere (mostly N2) and polar ice cap of
solid N2
Triton
• Giant faults on surface
• Volcanoes of N2 ice vent
through surface of CH4
ice?
• Nepeid: highly eccentric
orbit (captured asteroid?)
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Pluto
Major Characteristics
• Discovered in 1930 by Tombaugh
• Smaller than the Moon, about
20% the size of the Earth
• Irregular orbit, tilted at 17°,
rotation rate about 6.5 days
• One moon - Charon (discovered
1978 by Christy)
• Surface is -240°C
• Planet or Kuiper belt object (One
of 200,000,000 comets)
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