Transcript Quark Presents: Holiday Tour of the Star System Sol

Quark’s Holiday Tour
Part II: the Inner Planets of Sol
Mars
Venus
Mercury
Terra
Jupiter
N. Lindsley-Griffin, 1998
Geology of Terrestrial Planets
Quark’s Holiday Tour
Composition - All have:
metallic core
siliceous mantle
basaltic crust
Relatively dense: 4 - 5.5 g/cm3
Different history from Jovians
All shaped by:
1. Impact cratering
2. Volcanism
3. Tectonism
4. Erosion and deposition
Terra
(“Earth”)
Luna
(“Moon”)
Venus
Mars
Mercury
Houghton-Mifflin, Dolgoff, 1998; N. Lindsley-Griffin, 1999
Evolution of Terrestrial Planets
Quark’s Holiday Tour
A planet’s evolution is controlled by how long internal heat lasts
Luna (Earth’s Moon) is small, became quiet 3 b.y. ago
Terra (“Earth”) is large, stilll hot, remains dynamic today
N. Lindsley-Griffin, 1999
Atmospheres - Venus, Earth, Mars Quark’s Holiday Tour
Venus - runaway greenhouse effect
No plate tectonics
Too much Solar energy
Earth - plate tectonics recycles oxygen
by subducting and remelting
oceanic lithosphere and sediments
Carbon dioxide trapped biogenically
Size and mass just right to maintain
internal heat that drives tectonic cycle
Mars - water, oxygen locked up in rocks
No plate tectonics
Too small to hold dense atmosphere
Houghton-Mifflin, Dolgoff, 1998; N. Lindsley-Griffin, 1999
Venus - carbon dioxide
Earth - nitrogen/oxygen
Mars - carbon dioxide
LUNA
Crater Density and Age of Surface
Many craters on older, original lunar crust
(anorthosite brecciated by repeated impacts)
Crater Density
(arbitrary units)
Quark’s Holiday Tour
A
Fewer craters on younger crust of basalt in
the lunar mare (dark colored basins)
Crater density provides relative dating for
lunar surfaces
B
N. Lindsley-Griffin, 1999
C
b.y. ago
D
MARS: Tectonics
Quark’s Holiday Tour
Huge rift valleys (grabens) cut the northern hemisphere
Valles Marineris, largest canyon in the solar system, is
4500 km long, 2-7 km deep, formed by crustal rifting
Tharsis Bulge,
shield volcanoes
N. Lindsley-Griffin, 1998
Valles
Marineris,
a graben
MARS: Olympus Mons
Quark’s Holiday Tour
Largest volcano in the
solar system
Shield Volcano
Summit Caldera
Larger than the entire
Hawaiian islands
No linear track (therefore
no plate tectonics)
N. Lindsley-Griffin, 1998
MARS: Atmosphere
Quark’s Holiday Tour
Atmosphere is thin,
rich in CO2
Iron in rocks has
weathered to red oxides
Winds produce ventifacts
and dune fields, deposit
wind-blown sediments
N. Lindsley-Griffin, 1998
MARS: Climate and Ice Caps
Quark’s Holiday Tour
Strongly elliptical orbit causes
huge variation in seasons
Average temp. -55°C (-67°F),
but ranges from winter low of
-133°C (-207°F) to summer high of
27°C (80°F)
Ice caps wax and wane with the
seasons, causing 25% change in
global atmospheric pressure
Ice caps at both poles
are carbon dioxide
(“dry ice”) with dust
and minor water ice.
N. Lindsley-Griffin, 1998
MARS: Water Cycle
Quark’s Holiday Tour
Liquid water cannot exist on surface today
No water cycle active today
Evidence of
water erosion
and deposition
in the past
Major climate change
N. Lindsley-Griffin, 1998
MARS: Water Cycle
Quark’s Holiday Tour
Large floods
Small river systems
Large lakes or even oceans
Runoff caused by impact?
Nirgal Vallis, a runoff channel
Fault-bounded canyon
N. Lindsley-Griffin, 1998
VENUS: Atmosphere
Quark’s Holiday Tour
Pressure: 90 atm.
Dense clouds of CO2 and
sulfuric acid conceal surface
Runaway greenhouse effect
traps solar heat at surface
Surface temperature 500o C
(melts lead)
N. Lindsley-Griffin, 1998
VENUS: Radar View of Surface
Quark’s Holiday Tour
No rivers, oceans
Surface 500°C greenschist
metamorphism
No plate tectonics only hot spot
volcanism
N. Lindsley-Griffin, 1998
VENUS: Mountains and Faults
Quark’s Holiday Tour
Linear features are
tension cracks
(normal faults)
Structures are
horsts and grabens
like the Basin and
Range Province
Form over rising or
sinking mantle
plumes
N. Lindsley-Griffin, 1998
Normal Faults
Grabens
VENUS: Volcanoes, Lava Flows
Quark’s Holiday Tour
Radar images show large shield volcanoes
Entirely basaltic crust
Sif Mons, a shield volcano
- no granite
Fresh, uncratered
lava flows
Dark lava flows are
smooth, less reflective,
pahoehoe lava
Bright radar images
are rough aa lava
N. Lindsley-Griffin, 1998
Maat Mons Volcano, Venus
Younger Impact
Crater
Older Lava Flow
Younger Lava Flow
Older Lava Flow
The entire surface of Venus is covered by 500 m.y. basalt
Suggests a catastrophic resurfacing event
Sparse impact crater density -little modification since then
N. Lindsley-Griffin, 1998
MERCURY
Quark’s Holiday Tour
Closest planet to Sol
Smaller than all other
planets except Pluto
No atmosphere
Rotates only 3 times in 2
of its years
N. Lindsley-Griffin, 1998
MERCURY: Geology
Quark’s Holiday Tour
Surface very old, heavily cratered, similar to Luna
Huge lava plains like Lunar maria
N. Lindsley-Griffin, 1998
Sol: Close Approach
Quark’s Holiday Tour
As we zoom around Sol on
our way to Terra….
Solar flare or prominence
Dark sunspots are relatively
“cool” regions
N. Lindsley-Griffin, 1998
TERRA - LUNA
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The moon Luna is 1/4
the diameter of Terra
Some scientists consider
these to be paired planets
like Pluto - Charon
Luna’s relatively great
mass affects ocean tides
on Terra
N. Lindsley-Griffin, 1998
LUNAR GEOLOGY
Quark’s Holiday Tour
Terrae, or lunar
highlands (red color),
the older crust under
basalt lava flows
Maria, or lunar lava
flows, (blue and orange
color) are the younger
lowlands
Tycho crater:
Rays of young ejecta
cut across older
features
Houghton-Mifflin, Dolgoff, 1998; N. Lindsley-Griffin, 1999
LUNAR METEORITE IMPACT
Quark’s Holiday Tour
Large crater excavated by impact.
Meteorite disintegrates, debris scatters all around.
Secondary craters formed by impact of larger ejecta fragments.
Houghton-Mifflin, Dolgoff, 1998; N. Lindsley-Griffin, 1999
LUNAR METEORITE IMPACT
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ORIGIN OF LUNAR MARIA
Impact forms normal faults
and ring fractures around
crater
Basaltic magma forms by
pressure-release melting,
ascends through fractures
to fill crater.
Result: younger, less cratered
basaltic maria.
Houghton-Mifflin, Dolgoff, 1998; N. Lindsley-Griffin, 1999
LUNA
Crater Density and Age of Surface
Many craters on older, original lunar crust
(anorthosite brecciated by repeated impacts)
Crater Density
(arbitrary units)
Quark’s Holiday Tour
A
Fewer craters on younger crust of basalt in
the lunar mare (dark colored basins)
Crater density provides relative dating for
lunar surfaces
B
N. Lindsley-Griffin, 1999
C
b.y. ago
D
TERRA: Unique!
Quark’s Holiday Tour
Oxygen-rich atmosphere
Over 70% surface is water
Plate tectonics recycles
oxygen and water
Only known life in Solar System (but is
it intelligent?)
N. Lindsley-Griffin, 1998
TERRA: Intelligence?
Quark’s Holiday Tour
Hope for the future:
The U-manz (Terrans) are building a space station.
- a primitive step towards exploring the universe
- people and nations who were enemies not long ago are
working together.
Let’s hope they finish
growing up before
they invade us!
N. Lindsley-Griffin, 2000
THAT CONCLUDES OUR TOUR
Enjoy your Holiday!
Quiz 9 - 100 pts. extra credit over the locations on this
tour of the solar system - will be active until 5:00 PM
Wednesday Dec. 13
N. Lindsley-Griffin, 1998