Chapter 6: The Terrestrial Planets - Earth

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Chapter 6 The Terrestrial Planets - Earth
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From the Earth, Venus appears as a white planet
in the evening sky or the morning sky. From
Mars, the Earth might appear as an evening star
just after this sunset (photo taken by a
Rover on the Mars surface).
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Just after a sunset on Mars, the Earth appeared
as a pale blue planet in the evening sky.
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A closer look reveals a planet ¾ -covered with
liquid water
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Earths Atmosphere is layered.
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Convection heats the lower atmosphere,
distributing heat from the ground.
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The Greenhouse Effect plays a major role in
heating the Earths atmosphere.
Factors include Clouds Water vapor Agriculture
City heat islands Carbon dioxide Methane CFC
gases Dust and pollution Snow cover Desertificatio
n
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Global Warming is definitely occurring, but this
may be due to several reasons.
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Global Warming may be due partly to increasing
carbon dioxide levels which increase the
Greenhouse effect .The data below is from ice
cores, which have trapped air.
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Ice cores from Antarctica show the trends in
carbon dioxide levels for the last 1000 years. x
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Ice cores from Antarctica show the trends in
carbon dioxide levels for the last 800,000
years including four ice ages. x
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Increasing carbon dioxide levels have been
measured on the Hawaiian volcano, Mauna Loa.
This data is known as the Keeling curve
(link).More data is available from Australia
(link).
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Earths interior is revealed by seismology, the
study of earthquakes. Layers are revealed
A layered object Inner core Outer
core Mantle Crust Hydrosphere Atmosphere Magnetosp
here
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Observation of Seismic Waves due to earthquakes
reveals the interior structure of the Earth
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Earths InteriorThe mantle is about 80 of the
volume of the Earth. It is mostly a rocky
material (basalt).The core is believed to be
mostly iron and nickel, but could have many of
the heavier elements.There is certainly some
uranium and other radioactive elements which
produce heat that keeps the core hot. High
pressure causes the inner core to be a solid. The
outer core is liquid. We will compare this
structure with other planets structures.
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Global Plates move slowly plate tectonics The
motion at their boundaries causes earthquakes.
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Himalayas are due to colliding tectonic plates.
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Californian Fault (San Andreas fault) is where
plates are slipping and cause earthquakes.
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Plate Drift causes many effects earthquakes,
rift valleys, mountain chains, volcanoes,
mid-Atlantic ridge, etc.
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Earths Magnetosphere varies in size, depending
on the solar wind.
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Van Allen Belts, named after James Van Allen
of the Univ. of Iowa, who sent instruments up
on early U.S. spacecraft. link
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The Aurora Borealis are due to charged particles
trapped in the Earths magnetic field, causing
air molecules to glow.