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Topic 2: Measuring Earth
How can we determine the shape of the
Earth?
What evidence do we have about the shape
of the Earth?
What are the parts or layers of the Earth?
What is the true shape
of the Earth?
The true shape is an
oblate spheroid. It is
bulging at the equator
and slightly flattened at
the poles.
What are the dimensions of the
Earth?
• 40,008 Km
• 12,714 Km
• 12,756 Km
• 40,076 Km
What evidence do we have that
proves the Earth is round?
•
•
Space photos
– satellites in space take pictures which show the
Earth to appear smooth & round.
Motions of ships sailing towards the horizon
– Ships sailing toward the horizon seem to
disappear from bottom to top.
What evidence do we have that
proves the Earth is round continued?
•Shape of Earth’s shadow during a lunar
eclipse
- The Earth casts a curved shadow on the
moon during a lunar eclipse.
•Altitude of Polaris
- Polaris remains fixed over the north pole but
as a person changes latitude so does the altitude of
Polaris.
What evidence is there that the
Earth is not perfectly round?
• If the Earth was perfectly round the gravity
measures would be that same, a person
would weigh the same everywhere, but
they don’t, objects weigh slightly more at
the poles and slightly less at the equator.
How would you describe the
smoothness of Earth’s surface?
• It is very smooth compared to its diameter.
What are the outer spheres of
the Earth?
• Atmosphere- the layer of gases that surrounds
the Earth.
• Lithosphere- The layer of rock that forms the
solid outer layer.
• Hydrosphere- The layer of liquid water which lies
between the atmosphere and the lithosphere.
What are the characteristics of
the atmosphere?
• Composed mainly of gases (nitrogen & oxygen)
• The least dense outer layer.
• The atmosphere is layered (stratified)
– Troposphere
– Stratosphere
– Mesosphere
– Thermosphere
• The boundaries between the
layers are called pauses
• All clouds and air traffic are
located in the troposphere.
What are the characteristics
of the hydrosphere?
• This layer makes up 70% of the Earth’s
surface
• This layer is thin, it is only 3.8 Km thick
• Composed of the H2O (Hydrogen &
Oxygen)
• H2O is mainly oceans
What are the characteristics
of the lithosphere?
• This layer is about 100 Km thick
• It is divided into sections called plates
• The upper portion of the lithosphere is
called the crust.
• Crust that is broken up and contains
organic matter, it is called soil.