Chapter 5 Earth and Moon

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Chapter 5 Earth and Moon
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What do you think?

• Will the ozone layer, which is now being
  depleted, naturally replenish itself?
• Does the Moon have a dark side, where it is
  forever night?
• Does the Moon rotate, and if so, how fast?
• What causes the ocean tides?
• When does the spring tide occur?

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Why might this planet be called the blue planet?
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The Earths atmosphere has evolved over billions
of years

• Earths early atmosphere was primarily hydrogen
  and helium left over from the formation of the
  solar system
• Earths second atmosphere was primarily CO2 and
  released from Earths interior by volcanoes
• Earths current atmosphere is a 4-to-1 mixture of
  nitrogen and oxygen which was created by
  biological activity.

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Earths atmospheric layers are defined by
temperature ranges
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Earths Ozone Layer

• Ozone is O3
• Protects the surface from hazardous UV radiation
  from the Sun
• Can be destroyed by synthetic chlorofluorocarbons
  (CFCs)
• Slowly replenishes itself as it is created from
  sunlight and lightning
• Earths protective ozone layer had to form
  before early life could move from the oceans onto
  dry land

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Plate tectonics produced major changes to the
Earths surface over the past 200 million years
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Pangea
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SEA FLOOR SPREADING The sea floor between the
North America and Europe is spreading apart
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Earths surface is composed of about nine major
plates which slowly move relative to one another
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Plate tectonics is driven by convective currents
in Earths mantle
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Earths interior consists of a rocky mantle and
an iron rich core
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The Earths magnetic field is caused by dynamo
movements in Earths core
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The Earths magnetic field shield us from the
stream of charged particles from the Sun called
the solar wind
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Relevance of Earths protective magnetosphere

• Solar Flares - violent explosions on the Sun
  releasing charged particles into the solar system
• Solar wind - dangerous stream of charged
  particles coming from the Sun
• Van Allen radiation belts - hazardous reservoir
  of charged particles surrounding Earth
• Northern Lights (Aurora Borealis)

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Aurora as seen from space
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Aurora surrounding the north geomagnetic pole as
seen from space
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The Moons surface is covered with craters,
plains, and mountains
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Mare Imbrium
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Visits to the Moon yielded invaluable information
about its history
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Lunar Soil is called Regolith
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Mare Basalt
Mare basalt is solidified lava similar to what
composes rocks on Earths sea floor.
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Anorthsite
Anorthsite is material from the original lunar
crust sometimes called the genesis rock and is
more than 4 billion years old
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Impact Breccias
Impact Breccias are rocks formed from combining
debris during a violent impact event
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Likely interior of the Moon
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The Moon probably formed from debris cast into
space when a huge planetesimal struck the young
Earth
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Gravitational forces produce the tides and keep
the same side of the Moon always facing the Earth
Synchronous rotation
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The gravitational force between Earth and Moon
results in tides
Large spring tides occur when the Sun and Moon
are aligned such that they BOTH pull on the
Earths water.
Smaller neap tides occur when the Sun and Moon
are misaligned such that they pull on the Earths
water in different directions.
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Bouncing laser beams off the Moon demonstrates
that it slowly moving away from the Earth
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What did you think?

• Will the ozone layer, which is now being
  depleted, naturally replenish itself?
• Yes, the ozone is created from normal oxygen
  molecules by the Suns ultraviolet radiation.
• Does the Moon have a dark side, where it is
  forever night?
• Half of the Moon is always dark, but that half is
  continually changing as the Moon orbits the
  Earth.
• Does the Moon rotate, and if so, how fast?
• The Moon rotates at the same rate that it
  revolves around the Earth. If the Moon didnt
  rotate, then as it revolved we would see
  different sides of it, which we dont.
• What causes the ocean tides?
• The tides are caused by gravitational forces,
  primarily from the Moon and Sun.
• When does the spring tide occur?
• Spring tides occur during each full and new Moon.

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Self-Check

• 1 Describe the chemical evolution of the Earths
  atmosphere.
• 2 Describe the basic characteristics of plate
  tectonics on the Earth, including the
  observational evidence and the underlying cause.
• 3 List the major divisions of the Earths
  interior and describe the chemical composition
  and relative physical conditions in each.
• 4 Describe the relationship of the Van Allen
  belts and the northern lights to the Earths
  magnetic field.
• 5 List the various layers in the Earths
  atmosphere and describe the physical
  characteristics by which they differ.
• 6 List and describe the nature and probable
  origin of lunar surface features visible in
  photographs.
• 7 Indicate the range in ages of lunar rocks
  taken from different areas on the lunar surface
  and explain what they indicate about the stages
  in the formation of the moon.
• 8 Describe the key elements of the collisional
  ejection theory and summarize the evidence that
  might support it.