Jupiter
Printable
version
April
11, 2000
Announcements
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Hand
in Homework 5
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Quiz
#2 in discussion section this week
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Covers
Chapters 18.1-18.6, 10,11,12
Jupiter
Preview
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Jupiter
overview
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Seeing
Jupiter from Earth
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Jupiter's
composition
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Cloud
top patterns
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Outer
atmosphere dynamics
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Comet
Shoemaker Levy 9 impact
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Jupiter's
Magnetic field, magnetosphere
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Spacecraft
visits
Jupiter
Overview
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Superlative planet
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Equatorial and polar rotation
rates different
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Differential rotation (like
sun)
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Inside and outside rotation
rates different
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Equatorial and polar diameters
different (oblate)
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Jovian planet (density is
lower than terrestrial)
Seeing
Jupiter from Earth
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Jupiter is a superior
planet (larger orbit)
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Opposition every 13 months
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One of the brightest objects
in the sky
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Looks big in a telescope
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Easy to see belts (dark)
and zones (light)
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Easy to see red spot
Jupiter
Composition
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Jupiter's average density
is 1330 kg/m3
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Rock density is 3000 kg/m3
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Jupiter can't have much rock
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Jupiter is not round
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oblate
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equatorial diameter 6.5%
larger than polar diameter
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Differential rotation: can't
be a solid body
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Jupiter has some rocky core
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Saturn probably has a smaller
core
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Jupiter is mostly gas
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hydrogen and helium
in same proportions as Sun
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formed at the same time as
the Sun
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Weight of gas in central
regions is HUGE
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rocky core may be compressed
to 20,000 kg/m3
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80 million atmospheres
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liquid metallic hydrogen
surrounds core
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unusual conductive form of
hydrogen
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caused by high pressure and
temperature
Cloud
Top Patterns
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Belts (dark) and zones (light)
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Great red spot
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storm raging since at least
1664 when first seen by Robert Hooke
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Changes size slightly, but
about as big as 3 Earths
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white ovals (two recently
merged)
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brown ovals
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patterns are pretty similar
in northern and southern hemispheres
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Clouds in 3 layers
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Ammonium: NH3
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Ammonium hydrosulfide: NH4SH
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Water
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Galileo Probe
failed to detect water clouds
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may have been a hole in the
water clouds
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Mystery: what causes the
colors?
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Outer
Atmospheric Dynamics
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Jupiter produces ~2 times
as much heat than it receives from the Sun!
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Probably residual heat from
formation
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larger bodies cool more slowly
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Jupiter rotates rapidly
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Convection cells broken by
rotation (like Earth)
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Zones (light) upwelling
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Belts (dark) downdraft
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Fastest winds in belt/zone
boundary (500 km/hr)
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Whitish clouds tend to be
high, cooler
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Brown ovals are holes in
clouds, show warmer layers below
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Exception: Great Red Spot
rises to high altitudes
Comet
Shoemaker-Levy 9 Impact
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Spectacular collision in
1994 between comet and Jupiter
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Comet had been one piece
until previous pass by Jupiter
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broke into more than 20 pieces
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Pieces hit Jupiter one by
one
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Left scars that healed up
after a few weeks
Jupiter's
Magnetic Field/Magnetosphere
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Generated
by circulating charges in liquid metallic hydrogen core
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analogy
to circulating charges in Earth's liquid iron core
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Jupiter's
field is more than 10 times stronger than Earth's
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Jupiter's
magnetic field tilted 11 degrees with respect to Jupiter's rotation axis,
rotates slower than atmosphere
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Equatorial:
9h 50m
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Magnetic
field: 9h 55m
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Carves
out magnetosphere in solar wind
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Recall
Earth's magnetosphere caused Aurora Borealis (Northern lights)
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Charge
stored in van Allen Belts
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Jupiter
has Aurora as well
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Jupiter's
stored charges flung out by fast rotation into a current sheet
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Visible
at radio wavelengths
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electrons
spiral around magnetic field lines
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oscillating
charges send out radio waves
Spacecraft
Visits
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Flyby
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Orbit
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Galileo
1995--present
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Sent
in atmosphere probe
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Cassini
Galileo
composite image of Great Red Spot
Jupiter
Summary
-
Jupiter
overview
-
Seeing
Jupiter from Earth
-
Jupiter's
composition
-
Cloud
top patterns
-
Outer
atmosphere dynamics
-
Comet
Shoemaker-Levy 9 impact
-
Jupiter's
Magnetic field, magnetosphere
Spacecraft
visits