Download Day 10 - Ch. 5

Chapter 6: The Terrestrial Planets - Earth
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).
Just after a sunset on Mars, the Earth appeared
as a pale blue planet in the evening sky.
A closer look reveals a planet
¾ -covered with liquid water
Earth’s Atmosphere is layered.
Convection heats the lower atmosphere,
distributing heat from the ground.
The Greenhouse Effect plays
a major role in heating the Earth’s atmosphere.
Factors include:
Clouds
Water vapor
Agriculture
City “heat islands”
Carbon dioxide
Methane
CFC gases
Dust and pollution
Snow cover
Desertification
Global Warming is definitely occurring,
but this may be due to several reasons.
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.
Ice cores from Antarctica
show the trends in
carbon dioxide levels for
the last 1000 years. x
Ice cores from Antarctica
show the trends in
carbon dioxide levels for
the last 800,000 years
including four ice ages. x
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).
Earth’s interior is revealed by seismology,
the study of earthquakes. Layers are revealed:
A layered object:
Inner core
Outer core
Mantle
Crust
Hydrosphere
Atmosphere
Magnetosphere
Observation of Seismic Waves due to earthquakes
reveals the interior structure of the Earth
Earth’s Interior
The 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 planet’s structures.
Global Plates move slowly – plate tectonics
The motion at their boundaries causes earthquakes.
Himalayas are due to colliding tectonic plates.
Californian Fault (San Andreas fault)
is where plates are slipping and cause earthquakes.
Plate Drift causes many effects: earthquakes, rift valleys,
mountain chains, volcanoes, mid-Atlantic ridge, etc.
Earth’s Magnetosphere varies in size,
depending on the solar wind.
Van Allen Belts,
named after
James Van Allen
of the
Univ. of Iowa,
who sent
instruments up
on early U.S.
spacecraft.
link
The Aurora Borealis are due to charged particles trapped in
the Earth’s magnetic field, causing air molecules to glow.