Download PDF file of Lecture 9a - Planet Jupiter

JUPITER
GLG-190 - The Planets
Chapter 9
LECTURE OUTLINE
Introduction
 Atmosphere composition
 Weather

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Zones and Belts
Storms
Cloud Layers
Internal structure
 Magnetic field

Sign spotted in
Edinburgh UK
GAS GIANT (JOVIAN) PLANETS
Orbit outside of asteroid belt
 Accreted in colder parts of
solar nebula beyond “snow
line”
 Mostly hydrogen and helium
 Thick cloudy atmospheres

snow line
TERRESTRIAL VS. JOVIAN PLANETS

Compositional differences from
inner planets shown by densities
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Jupiter: 1.33 g/cm3 (about same as
Sun)
Saturn: 0.7 g/cm3 (less than water)
Uranus 1.30 g/cm3
Neptune: 1.76 g/cm3
Values for inner planets and Moon
range from 3.3 to 5.5 g/cm3
Low densities indicate materials
less dense than rock and metal
 gas, liquid, and ice
BASIC JUPITER DATA
Orbital radius of 5.2 AU
 Largest planet
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Diameter = 11 x Dearth
Mass = 318 x Mearth (2.5x mass of
all other planets combined)
Low density: 1.33 g/cm3 (about
same as Sun)
 Short day: 9h 55m
 Axial tilt 3.1°
 Strong magnetic field
 63 confirmed satellites
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Four major moons: Io, Europa,
Ganymede, Callisto
Faint rings
JUPITER: ALMOST
A STAR?

Jupiter is almost as
large as a planet can
be…
At 13 MJupiter 
deuterium fusion into
helium occurs in the
core  brown dwarf
 At 70-80 MJupiter 
hydrogen fusion into
helium occurs in core
 low-mass star

Gliese 229 A and B
COMPOSITION OF UPPER ATMOSPHERE
Spectroscopic results
combined with Galileo
atmospheric probe (right)
measurements
 Mostly H + He (99%)
 Most measured elements
are enriched relative to H
(compared with Sun)


Lower solar ratios of
Xsun/Hsun  loss of H
during formation of
Jupiter
ATMOSPHERIC STRUCTURE



Top of troposphere (0.1 bar)
assigned altitude of “0 km”
(right)
Higher temperatures at low
altitudes due to internal heat
Altitudes and types of clouds
differ…
Ammonia (NH3) clouds 
highest/coldest
 Ammonium hydrosulfide (NH4SH)
clouds  intermediate levels
(color from breakdown to form
sulfur compounds?)
 Water ice clouds 
lowest/warmest

ROTATION & SHAPE
Jupiter is not solid  atmosphere rotates faster at equator
 Rapid rotation and gas/liquid structure yield equatorial bulge
 143,884 km (equatorial) vs. 133,709 km (polar)
 True rotation shown by measurements of rotation of
magnetic field  9 hr and 55 m 29.7 s

WEATHER OF JUPITER
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Alternating counter-flowing light zones and dark belts
Rapid rotation rate wraps convention cells around planet
Different colors  see different depths into atmosphere
Great Red Spot is top of large cyclone
Equatorial zones and belts rotate faster than those at higher
latitudes and at poles
ZONES AND BELTS ON JUPITER

Zones and belts are zonal jet
streams
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Light colored zones
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Wind direction alternates
between adjacent zones and
belts
Two always found next to each
other
Upward moving convective
currents
Cooling produces white clouds
of ammonia/water ice
Ice rains out
Darker belts

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Downward sinking “dry” gases
Lack of clouds allows view of
lower, darker layers
CLOUD BANDS
JUPITER'S ATMOSPHERIC CIRCULATION

Equatorial jet
Rotation 9 hr 50 m
 Eastward winds 360 km/h
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High latitude winds
Rotation 9 h 55 m (close to true rotation)
 East and westward winds 100 km/h max
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Polar vortex
DETAILED STRUCTURES

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Boundaries of zones and belts
have complex turbulence and
vortex phenomenon
Dominated by physics known
as fluid mechanics

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Dense cold atmosphere behaves
as fluid rather than gas
Fluid mechanics predict two
types of patterns
Viscous flow: fluid slips past a
second fluid of different density
 wave-like features form at
boundary of two fluids
 Turbulent flow: stream of fluid
breaks up into individual
elements, called eddies (eddies
can develop into cyclones)

CYCLONES
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
Energy to power turbulence in
Jupiter's atmosphere comes from
internal heat
Cyclones develop due to very large
Coriolis effect
Gases at lower latitudes travel faster
than at higher latitudes  spin
 Cyclones are regions of local high or
low pressure
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
Direction of spin differs in two
hemispheres
Brown ovals are low pressure
cyclones/storms in North
 White ovals are high pressure
cyclones/storms in South

Details of the
circulation patterns
of individual bands
Merging of
two storms in
a band
GREAT RED SPOT
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Large southern hurricane
18,000 x 12,000 km (2x size of Earth)
At least 300 years old (persists because of
large size?)
Associated clouds are 8 km above
neighboring cloud tops
IMPACTS ON JUPITER
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Comet Shoemaker-Levy 9
Torn apart by Jupiter’s gravity
Fragments penetrated below
ammonia clouds before exploding
 form holes into lower hotter
part of atmosphere
Produced dark S- and C-rich clouds
that dissipated after few months
IR image
showing 2
impact sites
(lower left)
Fragments of Shoemaker-Levy 9
JULY 20, 2009 IMPACT
Anniversary of Apollo 11 landing on Moon
 Completely unexpected we lack of knowledge of
distribution of small bodies in Solar System

INTERNAL STRUCTURE
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No samples available  theoretical models of interior


Need to determine behavior of hydrogen and helium at high
pressures and temperatures
Correct for effects of pressure (conditions at Jupiter’s center:
25000 K and 100 Mbar)
INTERNAL STRUCTURE

Pressures high enough to
form liquid metallic hydrogen
(H)
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Electrons not bound to atoms in
metallic structure  move
freely
Convection currents in liquid
metallic hydrogen produce
strong magnetic fields
Uppermost layer dominated
by molecular hydrogen (H2)

Other elements in small
abundances
HELIUM RAIN
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Dissolved He becomes
immiscible in upper part of
metallic hydrogen layer
(region labeled Helium
rainout)
Forms liquid He droplets in
He droplets sink deeper into
interior

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Produces He depletion of upper
atmosphere
Neon dissolves in He droplets
also sinks into interior

Accounts for depletion of Ne
seen in upper atmosphere
CORE

Rocky core needed to account for
details of gravity field (otherwise
no evidence for core)
Core is probably 14-18x Mearth
 Data from Juno probe (launched
Aug. 2011; arrive July 2016) will
better constrain core size
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Inner part of core composed of
silicate minerals, oxides, metals
Inner part of core surrounded by
layer of ices (methane, water,
ammonia)
All materials would have unknown
structures at such extreme high
pressures
INTERNAL HEAT
Infrared radiation (IR)
measurements done by
Voyager spacecraft and
Hubble telescope
 Jupiter gives off 1.67x more
heat than it gets from Sun
 Heat sources differ...
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Jupiter retains heat from
contraction from protosolar
nebula (may still be
contracting)
Potential energy released by
helium rain also probably
contributes heat, but to a much
lesser extent
JUPITER’S MAGNETOSPHERE

Magnetic field 19,000x
stronger than Earth’s
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Produced by electrical currents
flowing inside metallic hydrogen
interior
Inclined 10 relative to
rotational axis
N and S poles swapped
compared with Earth
Huge magnetosphere
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Magnetotail extends out to orbit
of Saturn
Large sea of trapped, charged
particles like Earth’s Van Allen
Belts
Vastly larger and more energetic
aurorae than on Earth
Sun (yellow) shown with Earth’s
magnetosphere inside (to scale)
RADIO EMISSIONS FROM JUPITER
 Two
sources of radio
emissions
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Thermal radiation
Shorter wavelength radio
waves produced by internal
heat (cyan)
 Distribution of wavelengths
followed Planck’s law
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Nonthermal radiation
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Longer wavelength radio
waves produced by
electrons spiraling in
magnetic field 
synchrotron radiation
SYNCHROTRON RADIATION
Synchrotron radiation
created when fast charged
particle interacts with
magnetic field
 Magnetic field causes
particles to change
direction by exerting force
on them perpendicular to
their movement direction
 Particles are accelerated
along spiraling curved path
and radiate radio waves
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AURORA
Strong magnetic field
captures charged
particles from solar wind
and ions ejected from Io
 Particles trapped in
inner magnetic belts and
reflected back and forth
between north and
south magnetic poles of
Jupiter
 Auroras produced from
this interaction

Location of Io’s
flux tube