Transcript 12. - University of California, Berkeley

Giant Planets
Neptune
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Uranus
Saturn
Jupiter
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Important Notes:
• Read Chapter 11: “Jovian Planet Systems”
• Homework #8 due Friday
(on today’s and Thursday’s lecture)
• Mars: Mark mid-semester position!
• Midterm #2: Tuesday, April 15
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Terrestrial (Rocky)
Outer 4 Planets: Gaseous Giants
The Solar System
© 2005 Pearson Education Inc., publishing as Addison-Wesley
The 4 “Giant Planets”
“Jovian Planets”:
• No solid surfaces !!!
Jupiter
Much higher mass & radius than Earth, Venus, Mars.
Saturn
Uranus
QuickTime™
and a
QuickTime™
and
a
H & He
H & He decompressor
TIFF (Uncompressed)
H2O,
TIFF (Uncompressed)
decompressor
are needed to see this picture.
(most common
H & He
are
needed
to
see
this
picture.
atoms in universe)
Neptune
H2O,
H & He
(text: “hydrogen compounds” =
water, methane, ammonia)
“Ice Giants”
All have Rock Cores: 10-15 Earth-Masses
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Next Lecture:
Moons orbiting the Giant Planets
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Jupiter’s Moon: Io
© 2005 Pearson Education Inc., publishing as Addison-Wesley
• A volcanic explosion
can be seen
silhouetted against
dark space over Io's
brilliant limb. Io
more volcanically
active than Earth.
Jupiter – King of the Planets
Mass = 0.001 solar (318 earths),
Radius = 11.2 Earths,
Density = 1.3 g/cc (1.3 x water)
Distance: 5.2AU
Orbital Period: 11.8 years
Rotation period: 9.9 hours.
Flattened Spheroid
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Saturn
Mass = 95 Earths
Radius = 9.4 Earths
Density = 0.7 gram/cm3 (floats)
Distance: 9.5 AU
Orbital Period: 29.4 years
Rotation period: 10.6 hours.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Rings: Composed of
billions of icy-rocks and icy dust (water
and silicates).
UranusOrbital Period: 84 years;
Mass = 14.5 Earths
Radius = 4.0 Earths
Density = 1.3 gram/cm3 = 1.3 x water
Distance: 19.2 AU
Rotation period: 17.2 hours.
Visible Light
•Featureless in visible light, because clouds
are below haze layer of methane (colder than Saturn).
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Infrared Light (Thermal Emission)
Neptune
© 2005 Pearson Education Inc., publishing as Addison-Wesley
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.
Cyclonic storms.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
GIANT PLANETS
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Spacecraft Reconnaisance
1980’s: Voyager 1 & 2
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Camera
Spectrometer
Measures spectral lines:
Chemical composition
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Visit all 4
giant planets
Spacecraft Reconnaisance;
Galileo Spacecraft
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
•Launched from Space
Shuttle 1989
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickT ime™ and a
T IFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Spacecraft Reconnaisance;
Arrived: 1995
Galileo Spacecraft
QuickTime™ and a
T IFF (Uncompressed) decompressor
are needed to see t his picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
2003:
Dropped into Jupiter’s
Atmosphere:
Measure Chemical
Composition:
97% hydrogen & helium
Plus 3% C, N, O, S, Si …
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Giant Planet’s Chemical Composition
Mostly Hydrogen and Helium
•Add H to:
C, N, O
C, N, O, H
Chemistry
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Why are the Jovian Planets
Massive and Gaseous (H, He) ?
• Formed beyond the frost line (3 AU):
so cold that ice particles exist with silicate dust.
• Ice and Dust collides, sticks grows into icy-rocky core.
• Core’s gravity captures H/He gas
• Planet attracts ices and dust that orbit
• Moons formed out of these disks: A miniature solar system.
Young Solar System:
Gas & Dust
Young Jupiter
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Quiz
If Jupiter formed in a protoplanetary disk
that had twice as much dust it:
a) Would have a bigger core
b) Might have more hydrogen
c) Might have more metallic hydrogen
d) All of the above
© 2005 Pearson Education Inc., publishing as Addison-Wesley
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
• Color Enhancement
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Hydrostatic Equilibrium: Pressure balance
Pressure at any depth = gravitational weight of column above
“Hydrostatic equilibrium” governs the structure of all planets.
The inside has higher pressure and density because of the weight of
the overlying material.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Inside Jupiter
• Jupiter emits almost twice as much energy as it absorbs from the Sun.
• accretion, differentiation, radioactivity can not account for it
• Jupiter must still be contracting
• Jupiter has 3 x more mass than Saturn, but is only slightly larger in radius!
• the added weight of H & He compresses the core to a higher density
• like stacking pillows
© 2005 Pearson Education Inc., publishing as Addison-Wesley
• If Jupiter had 10x its mass,
it would have same radius !
Add even more mass, and
Jupiter would get smaller !
• Jupiter is about as large as a
planet can get.
• Uranus & Neptune have
less mass than Saturn, yet
they have higher densities
• They must be made of
denser material:
• Rock & Ice !
Quiz
On the moon, a cup of sugar has some pressure, P,
at its bottom. You add 50% more sugar to the
cup. The new pressure at the bottom is:
a)
b)
c)
d)
0.5 P
1.0 P
1.5 P
2.0 P
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Inside Jupiter
No solid surface and consists mostly of H & He.
Distinct interior layers, defined by increasing density inward.
• Moving from the surface to the
core:
• temperature increases
• pressure & density increases
• Hydrogen atoms so dense:
Electrons not associated with
any one atom: Free- electrons.
Metallic Hydrogen!
• Jupiter's core is rock & ice:
~10 times the mass of Earth.
. . . Controversial.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Inside the Jovian Planets
• All Jovian cores appear to be similar.
• made of rock, metal, and Hydrogen compounds
• 10 x the mass of Earth
• Uranus & Neptune captured less gas from the Solar nebula.
• accretion of planetesimals took longer
• not much time for gas capture before nebula was cleared out by Solar wind
• Only Jupiter and Saturn have high enough pressure for H & He to
exist in liquid and metallic states.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Rotational Distortion
of Planet’s Shape
Centrifugal Force:
Flings material at equator outward
Due to Rotation
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Determining the Density inside a Rotating Planet
Use Motion of Orbiting Satellites
Rotation flattens shape
—> Less pull on satellite at poles
Higher density
toward center
—> Exerts Point-like Grav. Force
Track acceleration of
satellites accurately
—> Density throughout interior
© 2005 Pearson Education Inc., publishing as Addison-Wesley
- Another Effect of Planet’s Rotation -
The Great Red Spot
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Great Red Spot
A Hurricane that has
lasted 300 years
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Cyclonic Motions
Southern
Hemisphere
Northern
Hemisphere
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Coriolis effect:
Motion from
High Pressure area
Jovian Storms
• Red Spot: A High Pressure Storm
• Analogous to hurricanes, but they rotate in the opposite direction
• Jupiter
• the Great Red Spot
• we are not sure why it is red
• Neptune
• the Great Dark Spot
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Planet
Rotation
Neptune’s
Storms
scooter
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Quiz
You are standing on the equator of the Earth and
you throw a ball fast, directly toward the south
pole. The ball’s trajectory will
a)
b)
c)
d)
Carry it toward the south pole
Veer to the right
Veer to the left
Curl around in a spiral
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Altitude above clouds tops (km)
Jupiter’s Cloud Layers
• Convection in the troposphere causes
Jovian weather.
• Warm gas rises to cooler altitudes,
where it condenses to form clouds.
• Three gases condense in the Jovian
atmosphere:
• ammonia (NH3)
• ammonium hydrosulfide (NH4SH)
• water (H2O)
• They condense at different
temperatures, so their clouds form at
different altitudes.
Temperature
(C )
© 2005 Pearson Education Inc., publishing as Addison-Wesley
The Jovian Atmospheres
• The temperature profile of each
planet determines the color of its
appearance.
• Cloud layers form where a particular
gas condenses.
• Saturn has the same cloud layers as
Jupiter.
• they form deeper since Saturn is
colder overall
• they are spread farther apart since
Saturn has lower gravity
• Uranus & Neptune
• cold enough to form methane clouds
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Bands of Jupiter
What Causes them?
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Convection on Jupiter:
•Warm air rises
•Coriolis force
diverts path sideways
Coriolis force is due to
rotation of planet
•Jupiter rotates fast:
Period = 10 hours
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Wind Speed in Jupiter’s Bands
•1000 km/hr
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Winds of Jupiter’s Bands
Red Spot
in Southern
Hemisphere
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Jupiter
Uranus
Magnetic Fields
Neptune
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Saturn
Jupiter's Magnetosphere
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
•
Ion and neutral mass spectrometer
instrument on the Cassini spacecraft,
makes the huge magnetosphere
surrounding Jupiter visible. The
magnetosphere is a bubble of charged
particles trapped within the magnetic
environment of the planet. In this picture,
a magnetic field is sketched over the
image to place the energetic neutral atom
emissions in perspective.
•
Also shown for scale and location are the
disk of Jupiter (black circle) and the
approximate position (yellow circles) of
the doughnut-shaped torus created from
material spewed out by volcanoes on Io,
one of Jupiter's large moons.
Jupiter’s Magnetosphere –
Bigger than the Sun
Solar Wind
protons &
electrons
© 2005 Pearson Education Inc., publishing as Addison-Wesley
Jovian Magnetospheres
• Saturn, Uranus, & Neptune have smaller & weaker magnetospheres.
• fraction of electrically conducting material in interiors is smaller
• Solar wind is weaker farther out, or else their magnetospheres would be even smaller
• we can not explain the magnetic field tilts of Uranus & Neptune.
© 2005 Pearson Education Inc., publishing as Addison-Wesley
The high energy particles come down the field lines and hit the
atmosphere near the poles, causing the gases to glow. Just like on
the Earth, this makes an “aurora” in a ring-like zone.
Auroral Zones
© 2005 Pearson Education Inc., publishing as Addison-Wesley
The 4 “Jovian” Worlds
• Major features :
Massive: 14 - 300 x mass of Earth
Gaseous: Hydrogen, Helium & Water
Rocky Core (Si, O, Fe, Ni …)
Rotating Fast: 10 hours (squashed shape)
© 2005 Pearson Education Inc., publishing as Addison-Wesley