Transcript Unit 1 Goal 1: Unique Planet

Chapter 2.1
Earth: a Unique Planet
(Goal 1)
Three Reasons the Earth
is Unique …
It is the only known planet with liquid surface water.
It is the only known planet with an oxygen
atmosphere.
It is the only known planet to support life.
Three Facts About the
Earth …
The Earth is the third planet from the Sun.
The Earth is around 4.6 billion years old.
71% of the Earth's surface is covered by ocean.
http://www.history.com/shows/how-the-earth-was-made/videos/theage-of-earth
The Earth: an Oblate Spheroid
The Earth is not completely
round; therefore, we can’t
refer to it as a perfect
sphere.
The true shape of the Earth
is an oblate spheroid,
meaning a slightly flattened
sphere (In other words, the
Earth is slightly squished.).
The spinning of the Earth on
its axis causes it to flatten
slightly at the poles and
bulge in the middle.
The Circumference of the
Earth
Pole
Equator
The Earth’s
circumference is
40,007 km (24,859mi)
from pole to pole and
40,074 km(24,901mi)
around the Equator.
From the Tallest Mountain to
the Deepest Trench
The difference in height from the tallest
mountain to the deepest trench on Earth is
only 20 km (12.4mi).
http://www.history.com/shows/how-the-earth-wasmade/videos - deepest-place-on-earth
The Size of the Earth
The average
diameter of
the Earth is
12,756 km
(7,926mi).
How do we know about the Earth’s
interior?
The Earth’s interior is is studied with seismic waves
called P (primary) and S (secondary) waves.
•
P and S waves travel
faster through more
rigid, dense materials
and slower through
more plastic, less
dense materials. Both
types of waves are
deflected when they
enter a medium of
different density.
How do we know about the Earth’s
interior?
The Earth’s interior is is studied with seismic waves
called P (primary) and S (secondary) waves.
•
P waves are
deflected by the
liquid in the Earth’s
outer core and can’t
be detected between
103 to 143 from
an earthquake’s
epicenter.
How do we know about the Earth’s
interior?
The Earth’s interior is is studied with seismic waves
called P (primary) and S (secondary) waves.
•
S waves do not
travel through
liquids, such as the
Earth’s outer core
and therefore
can’t be detected
past 103 from an
earthquake’s
epicenter.
The Three Compositional Zones of
the Earth
The Earth is
divided into three
major
compositional
zones:
the crust,
the mantle,
and the core.
The Three Compositional Zones of
the Earth
The crust is by far
the thinnest layer (It
is less than 100 km or
62 mi thick)
The crust makes up
less than 1% of the
Earth’s mass.
The Three Compositional Zones of
the Earth
•The mantle and core
are 1000s of km
thick.
•The mantle is 2/3 of
Earth’s mass,
•and the core is 1/3
of Earth’s mass.
The Three Compositional Zones of
the Earth
The moho is found between the crust & the mantle.
The crust and the
mantle are composed
of rock. The core is
composed of denser
metals.
ALL parts of the
Earth core are solid
except the outer core
which is liquid.
Earth’s Crust …
Its Not All Created
Equally!!!
Oceanic Crust – the Earth’s crust under the oceans that
makes up the ocean basins (ranges from 5 to 10 km
thick).
Continental Crust – the Earth’s crust that makes up the
continental landmasses (ranges from 15 to 80 km thick).
Ocean crust is made of a more dense material
than continental crust.
The Five Structural Zones of
the Earth
The Earth's five major structural zones: the lithosphere,
the asthenosphere, the mesosphere, the outer core, and
the inner core.
The thickness of the five zones are
as follows:
1. lithosphere - 15-300 km thick.
2. asthenosphere - 200-250 km
thick.
3. mesosphere - ends at a depth of
2900 km.
4. outer core - begins at a depth of
2900 km and goes down to 5150
km thick.
5. inner core - begins at 5150 km
thick and goes to the center of
the Earth.
The Lithosphere and the
Asthenosphere
Lithosphere – the Earth’s
crust (both oceanic and
continental) combined with
the rigid, brittle upper
mantle that forms the
outer shell of the Earth.
The less dense, lithospheric plates, including the
oceanic and continental crust, “float” on the more
dense, “plastic” asthenosphere directly below.
The Lithosphere and the
Asthenosphere
Asthenosphere – part of
the “plastic” (i.e. It
flows.), lower mantle
directly underneath
the lithosphere. The
asthenosphere is
plastic because of the
pressure on it from
the lithosphere above.
The Earth’s Magnetosphere
The Earth’s magnetosphere is the name given to the Earth’s magnetic
field.This field extends from the magnetic North Pole to magnetic
South Pole and out into space.
It’s currently believed that the
movement of molten iron in the
Earth’s outer core causes the
production of electric currents
which in turn produce the
Earth’s magnetic field.
Mass vs. Weight
Newton’s Law of Gravitation states that the force of attraction
(gravity) between two objects depends on their masses and the
distance between them. The more massive they are and the closer
they are together, the greater the attraction.
Mass is the amount of matter that makes up an object. Weight is the
effect of gravity on that mass.
The father you are from the
center of the Earth, the less
your weight. Therefore, your
weight decreases as you
travel from a pole to the
equator, up a mountain, or
off the surface of the Earth
(ex. On the surface of the
Earth, a 1 kg mass = a 10 N
weight/At 13,400 km above
the Earth’s surface, a 1 km
mass = a 1 N weight.).
weight decreases
mass is constant
weight increases
mass is constant