Download 05 Earth Moon

Chapter 5
Earth and Its
Moon
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Chapter 5
Earth and Its Moon
Copyright © 2010 Pearson Education, Inc.
Tatoonie
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Units of Chapter 5
Earth and the Moon in Bulk
The Tides
Atmospheres
Interiors
Surface Activity on Earth
The Surface of the Moon
Magnetospheres
History of the Earth–Moon System
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Question 1
The Moon’s internal
structure is similar
to Earth’s, but the
Moon lacks
a) an atmosphere.
b) a hydrosphere.
c) a magnetosphere.
d) It lacks all of the above.
Question 1
The Moon’s internal
structure is similar
to Earth’s, but the
Moon lacks
a) an atmosphere.
b) a hydrosphere.
c) a magnetosphere.
d) It lacks all of the above.
Both the Earth and Moon have a core, mantle, and crust, but the
Earth has a liquid water-rich layer, air, and a magnetic field.
Earth and the Moon in Bulk
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The Tides
Tides are due to
gravitational force
on Earth from
Moon – force on
near side of Earth
is greater than
force on far side.
Water can flow
freely in
response.
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The Tides
The Sun has less
effect, but it does
modify the lunar
tides.
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Question 2
At what lunar phase
would the variation
between high & low
tides be greatest?
a) new moon
b) waxing crescent moon
c) full moon
d) third quarter moon
e) both new and full moon
Question 2
At what lunar phase
would the variation
between high & low
tides be greatest?
a) new moon
b) waxing crescent moon
c) full moon
d) third quarter moon
e) both new and full moon
At new and full moon
phases, the Sun and Moon
combine to stretch the Earth
and its oceans even more.
We see higher high tides
and lower low tides.
The Tides
Tides tend to exert a “drag” force on Earth,
slowing its rotation.
This will continue until Earth rotates
synchronously with the Moon, so that the same
side of Earth always points toward the Moon.
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The Tides
This has already
happened with
the Moon,
whose near side
is always toward
Earth.
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Question 3
What force riveted
the Moon’s near
side to constantly
face Earth?
a) the Sun’s gravity
b) Earth’s magnetic field
c) Earth’s tidal force
d) the solar wind
e) the Moon’s magnetic field
Question 3
What force rivets
the Moon’s near
side to constantly
face Earth?
a) the Sun’s gravity
b) Earth’s magnetic field
c) Earth’s tidal force
d) the solar wind
e) the Moon’s magnetic field
Just as the Moon creates tides
on Earth with its gravitational
force, the Earth affects the
Moon, too.
Because of Earth’s tidal force,
the Moon spins once a month.
Atmospheres
• The blue curve
shows the
temperature at
each altitude.
• Troposphere is
where convection
takes place –
responsible for
weather.
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Atmospheres
Convection depends on warming of
ground by the Sun.
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Atmospheres
Ionosphere is ionized by
solar radiation, and is a
good conductor.
Reflects radio waves in
the AM range, but
transparent to FM and
TV.
Ozone layer is in the
stratosphere and
absorbs ultraviolet
radiation.
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Earth’s Growing Ozone Hole
Chlorofluorocarbons
(CFCs) have been
damaging the ozone
layer, resulting in
ozone hole.
1 chlorine atom can
destroy up to a
100,000 ozone
molecules. It will be
decades before the
hole will go away.
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Question 4
A planetary
atmosphere with
ozone could
protect surface
dwellers from
a) ultraviolet radiation.
b) charged particles in the solar wind.
c) meteor impacts.
d) optical radiation.
e) radar waves.
Question 4
A planetary
atmosphere with
ozone could
protect surface
dwellers from
a) ultraviolet radiation.
b) charged particles in the solar wind.
c) meteor impacts.
d) optical radiation.
e) radar waves.
Ozone in the stratosphere
(about 30-50 km high)
absorbs UV light, and heats
the upper atmosphere.
Atmospheres
Surface heating:
• Sunlight that is not reflected is
absorbed by Earth’s surface, warming it.
• Surface re-radiates as infrared thermal
radiation.
• Atmosphere absorbs some infrared,
causing further heating.
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Atmospheres
This is known as the
greenhouse effect.
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Question 5
The principal
greenhouse gases
in our present
atmosphere are
a) hydrogen and helium.
b) oxygen and nitrogen.
c) water vapor and carbon dioxide.
d) methane and ammonia.
e) sulfuric acid vapor and CO2.
Question 5
The principal
greenhouse gases
in our present
atmosphere are
a) hydrogen and helium.
b) oxygen and nitrogen.
c) water vapor and carbon dioxide.
d) methane and ammonia.
e) sulfuric acid vapor and CO2.
A greenhouse gas lets shorterwavelength light pass through, but
absorbs longer-wavelength light.
The Greenhouse Effect and Global
Warming
There is extremely strong evidence that Earth is
getting warmer. The cause of this warming is a
subject of intense debate; many scientists
believe it is related to the corresponding
increase in atmospheric carbon dioxide.
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Greenhouse Effect
• Some greenhouse gas is necessary.
Without a trace of GHG Earth would be
-19 C instead of +14 C.
• Too much GHG and Earth gets too hot.
• GHG such as water vapor, CO2 and
Methane.
Question 6
Without the
greenhouse effect
in our atmosphere
a) we would not have to worry about
ecological problems.
b) the Earth’s oceans would be frozen.
c) the amount of nitrogen & oxygen
would be much less.
d) the icecaps would have melted.
e) global warming would still occur.
Question 6
Without the
greenhouse effect
in our atmosphere
a) we would not have to worry about
ecological problems.
b) the Earth’s oceans would be frozen.
c) the amount of nitrogen & oxygen
would be much less.
d) the icecaps would have melted.
e) global warming would still occur.
Earth’s greenhouse effect makes the planet
about 40° C hotter than it would otherwise be.
This raises the average surface temperature
above the freezing point of water.
Interiors
Seismic waves:
• Earthquakes produce both pressure and
shear waves.
• Pressure waves will travel through both
liquids and solids.
• Shear waves will not travel through liquids, as
liquids do not resist shear forces.
• Wave speed depends on density of material.
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Interiors
The pressure
wave is a
longitudinal
wave, whereas
the shear wave
is a transverse
wave. A shear
wave cannot
propagate within
a liquid.
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P - wave
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S - Wave
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Interiors
Can use pattern
of reflections
during earthquakes
to deduce interior
structure of Earth.
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Interiors
Currently accepted model
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Interiors
Mantle is much less dense than core.
Mantle is rocky; core is metallic, consisting
of iron and nickel.
Outer core is liquid; inner core is solid, due
to pressure.
Volcanic lava comes from mantle, allows
analysis of composition.
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Surface Activity on Earth
Continental drift: Earth’s entire surface is covered
with crustal plates, which can move independently.
At plate boundaries, earthquakes and volcanoes
can occur.
Volcano
earthquake
Plate line
Drift
Direction
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San Andreas Fault
2 inches per year
21 feet in 1906 quake
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Surface Activity on Earth
Plates moving away from each other create
rifts.
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5.5 Surface Activity on Earth
If we follow the continental drift backward, the
continents merge into one, called Pangaea.
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The Surface of the Moon
The Moon has large dark flat areas, due to lava
flow, called maria (early observers thought they
were oceans).
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The Surface of the Moon
The far side of the
Moon is relatively
unmarked.
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Question 7
Lunar maria are
found
a) uniformly all over the Moon.
b) mostly on the side facing Earth.
c) mostly on the far side of the Moon.
d) only in the dark areas, out of sunlight.
e) in the highlands, among mountains.
Question 7
Lunar maria are
found
a) uniformly all over the Moon.
b) mostly on the side facing Earth.
c) mostly on the far side of the Moon.
d) only in the dark areas, out of sunlight.
e) in the highlands, among mountains.
Because the Moon keeps its near
side always facing Earth, that side
has a thinner crust, and is also less
cratered.
The Surface of the Moon
Crater formation: Meteoroid strikes the Moon,
ejecting material; explosion ejects more material,
leaving a crater.
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The Surface of the Moon
• Craters are typically about 10 times as wide as
the meteoroid creating them, and twice as deep.
• Rock is pulverized to a much greater depth.
• Most lunar craters date to at least 3.9 billion
years ago; much less bombardment since then.
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The Surface of the Moon
Very large and very small lunar craters
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The Surface of the Moon
Regolith: Thick layer of
dust left by meteorite
impacts
The Moon is still being
bombarded, especially
by very small
“micrometeoroids”;
softens features.
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Magnetospheres
The magnetosphere is the region around Earth
where charged particles from the solar wind are
trapped.
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Magnetospheres
These charged
particles are
trapped in areas
called the Van Allen
belts, where they
spiral around the
magnetic field
lines.
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Question 8
The region around
Earth where the
magnetic field traps
charged particles is the
a) ozone layer.
b) exosphere.
c) Van Allen radiation belts.
d) corona.
e) aurora borealis and australis.
Question 8
The region around
Earth where the
magnetic field traps
charged particles is the
a) ozone layer.
b) exosphere.
c) Van Allen radiation belts.
d) corona.
e) aurora borealis and australis.
The Earth’s magnetosphere
influences the charged
particles of the solar wind.
Some particles are
channeled toward the poles,
creating the aurora.
Magnetospheres
Near the poles,
the Van Allen
belts intersect
the atmosphere.
The charged
particles can
escape; when
they do, they
create glowing
light called an
aurora.
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Question 9
Which of these is
NOT a result of
the Earth’s
magnetic field?
a) a compass pointing north
b) aurorae
c) the Van Allen radiation belts
d) volcanic eruptions
e) the comet-like tail of charged
particles that extends past our Moon
Question 9
Which of these is
NOT a result of
the Earth’s
magnetic field?
a) a compass pointing north
b) aurorae
c) the Van Allen radiation belts
d) volcanic eruptions
e) the comet-like tail of charged
particles that extends past our Moon
Our planet’s
magnetosphere is
generated by the
Earth’s rotation and
its liquid metal core.
In contrast, the Moon
doesn’t have a
magnetic field.
History of the Earth–Moon System
Current theory of
the Moon’s origin:
glancing impact of
Mars-sized body on
the still-liquid Earth
caused enough
material, mostly
from the mantle, to
be ejected to form
the Moon.
Computer model
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History of the Earth–Moon System
Four billion years ago, the Moon had many
craters but no maria. By three billion years ago,
the maria had formed. Now, they also are
covered with craters.
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Question 10
Today, which of these
theories best explains
the Moon’s origin?
a) The fission theory
b) The giant impact theory
c) The capture theory
d) The co-formation theory
e) The fusion theory
Question 10
Today, which of these
theories best explains
the Moon’s origin?
a) The fission theory
b) The giant impact theory
c) The capture theory
d) The co-formation theory
e) The fusion theory
The giant impact theory seems to explain why the Moon is
similar to Earth’s mantle, and why it doesn’t have a dense core.
Giant Impact Theory