Download Earth: A Unique Planet

Bell Questions 9/8/11
1. List three things that make Earth Unique.
2. List the three Compositional Zones of the
Earth.
Earth: A Unique Planet
Earth Basics
• Earth is the third planet from the sun.
• Earth formed about 4.6 billion years ago
• Made mostly of rock.
• Approximately 70% of Earth’s surface is covered
by the global ocean.
• Earth is an oblate sphere, or a slightly flattened
sphere.
• Earth’s average diameter is 12,756 km.
Earth’s Interior
• Scientists use seismic waves to find out
about Earth’s interior.
• Seismic waves caused by earthquakes
and explosions near surface.
• P waves – through solids and liquids
• S waves – through solids only
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Earth’s Interior
The diagram below shows the layers of Earth’s interior.
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Compositional Zones
1. Crust the thin and solid outermost layer
2. Mantle the layer of rock that lies between
Earth’s crust and core. The mantle is
nearly 2,900 km thick.
3. Core the central part of Earth, composed
mainly of nickel and iron whose radius is
about 3,500 km.
Structural Zones
1. lithosphere the solid, outer layer of Earth that
consists of the crust and the rigid upper part of
the mantle
2. asthenosphere the solid, plastic layer of the
mantle beneath the lithosphere; flows very
slowly
3. mesosphere the “middle sphere”; the strong,
lower part of the mantle between the
asthenosphere and the outer core
Structural Zones (cont.)
4. Liquid outer core - below the mesosphere
5. Solid inner core – surrounded by the
outer core and begins at a depth of 5,150
km.
Earth’s Interior
1. What three compositional zones make up Earth’s
interior?
2. Which compositional zone of Earth makes up
almost two-thirds of the planet’s mass?
3. The asthenosphere floats on which structural
zone?
4. What structural zones make up Earth’s interior?
5. Where is the Moho found?
6. The mantle is made up of what structural zones?
Bell Questions 9/9/11
1. What are the five structural zones?
2. How do we know the outer core of the
Earth is liquid?
Earth as a Magnet
• Earth’s magnetic field
extends beyond the
atmosphere and affects a
region of space called the
magnetosphere.
• Motions within the liquid
iron of Earth’s outer core
produce electric currents
that in turn create Earth’s
magnetic field.
Earth’s Gravity
• Gravity is the force of attraction that exists
between all matter in the universe.
• The force of attraction between any two objects
depends on the masses of the objects and the
distance between the objects.
The force of gravity acts between all objects
If mass increases, the force of gravity increases
If distance increases, the force of gravity decreases
Earth’s Gravity
Weight and Mass
• Weight is a measure of the strength of the pull of gravity
on an object. (Newton)
• An object’s weight depends on its mass and its distance
from Earth’s center.
Weight and Location
• More distance between center and surface of the earth
at the equator so an object’s weight is about 0.3% less
than at the poles.