Earth

1
Earths Structure

• Earth is not Jupiter

2
Introduction

• We have explored outer space much more
  extensively than we have explored the inside of
  our own planet.
• Why havent we explored the inside of our planet
  more carefully?
• There are 3 major reasons.

3
Introduction

• 1- Technology/money
• We have developed all types of technology to
  enter and study outer space, but we dont have
  much technology to help us study the inside of
  the earth.
• Drilling into the earth is time consuming and
  expensive.

4
Introduction

• 2- Accessibility
• Getting into the earth is very difficult.
• The deepest well ever drilled was in Russia. It
  took 24 years, and it is less than 13 kilometers
  (about 7.6 miles) deep.
• This is less than halfway through earths crust.

5
Introduction

• 3- Climate
• The deeper you go into the earth, the hotter it
  gets.
• The Kola peninsula well (in Russia) reached
  temperatures of 180 degrees C (356 degrees F),
  and they werent even halfway through the crust!
• At the temperatures that would be reached even
  halfway through the crust, drills would be
  melting!
• There is also extreme pressure as you go deeper
  down.

6
Learning about the Earth

• Most of the information that scientists have been
  able to learn about the earths interior has come
  from shock waves produced by earthquakes.

7
Learning about the Earth

• Earthquakes are produced when the earths
  uppermost layer moves suddenly.
• Earthquakes produce shock waves that travel
  through the earth.
• Another name for shock waves is seismic waves.

8
Learning about the Earth

• Seismic waves always start from their point of
  origin, and travel outward like ripples on a
  pond.
• Scientists learn about the inside of the earth by
  studying how fast these waves move, how long it
  takes for them to slow down, and how long it
  takes for them to disappear.
• Video

9
Learning about the Earth

• The two types of seismic waves that have been
  most helpful to scientists are called P waves and
  S waves.
• Video

10
Learning about the Earth

• P waves dont travel well through liquid, and S
  waves dont travel at all through liquid.
  Neither wave will travel through a gas.
• Using this knowledge, scientists have been able
  to develop a model of what the inside of the
  earth may look like.

11
The Earths Core Outer Core

• At 2,900 kilometers below the earths surface,
  the P waves slow down, and the S waves disappear.
• This indicates that there is a liquid section
  that begins 2,900 Km beneath the earths surface.

12
The Earths Core Inner Core

• At 5150 Km below the earths surface, the P waves
  speed up again.
• This indicates that there is a solid section that
  begins 5150 Km beneath the earths surface.

13
The Earths Core

• After observing the speeds of P and S waves,
  scientists have concluded that the Earths
  center, or core, is actually made up of 2 layers
• The Outer Core
• The Inner Core

14
The Earths Core Inner Core

• The innermost, solid, layer of the earth is
  called the inner core.
• The inner core is made of Iron (Fe) and Nickel
  (Ni)

15
The Earths Core Inner Core

• The inner core reaches temperatures of 5000
  degrees C (9032 degrees F)!
• The surface of the sun is about 5,506 degrees C.
• Normally these temperatures would melt the nickel
  and iron causing the inner core to be liquid, but

16
The Earths Core Inner Core

• the extreme pressure from all the other layers
  of the earth pushing in on the inner core cause
  the atoms to move very closely together.
• This causes the inner core to be a solid rather
  than a liquid.

17
The Earths Core Inner Core

• The inner core begins at a depth of about 5150 Km
  below the earths surface, and has a radius of
  about 1300 Km (about 807 miles)!
• From here to Disneyland is about 639 miles.

18
The Earths Core Outer Core

• The outer Core is the layer of the earth that
  surrounds the inner core.
• The outer Core begins at 2,900 Km below earths
  surface, and is around 2200 degrees C (3392
  degrees F).

19
The Earths Core Outer Core

• The outer core is also made of nickel and iron,
  but the nickel and iron are liquids in the outer
  core.
• This layer is liquid because the temperature is
  still very high, but the pressure is not as great
  as it is in the inner core.

20
The Earths Mantle

• The Earths mantle is located above the outer
  core.
• The mantle goes from 30 Km to about 2900 Km below
  the earths surface.
• This is the thickest layer of the earth.

21
The Earths Mantle

• The boundary between the crust and mantle is
  called the Moho
• The Moho, or Mohorovicic Boundary, was named
  after the Yugoslav scientist who first observed a
  change in wave speeds as they moved 30-60 Km
  below earths surface.

22
The Earths Mantle

• The mantle is made mostly from Silicon (Si),
  Oxygen (O), Magnesium (Mg), and Iron (Fe) rocks.

23
The Earths Mantle

• The deeper you go through the mantle, the greater
  the density is.
• This is because there are greater amounts of Iron
  deeper in the mantle.

24
The Earths Mantle

• The temperature and pressure of the mantle
  increase as you move further down.
• The temperature of the mantle ranges from 870
  degrees C in the upper portions, to 2,200 degrees
  C in the lower portions.

25
The Earths crust

• The Earths crust is its thin, outermost layer.
• The crust is much thinner than the mantle or the
  inner or outer cores.

26
The Earths crust

• The three main types of rocks found in Earths
  crust are
• Sedimentary rocks
• Igneous rocks
• Metamorphic rocks

27
The Earths crust

• Sedimentary rocks make up 75-80 of the crust of
  the earth.
• Sedimentary rocks are made of small particles
  that are smashed together to form rocks.
• Sedimentary rocks are common on a beach.
• Limestone and Sandstone are sedimentary rocks.

28
The Earths crust

• Igneous rocks form from magma (melted rocks) that
  cool and become solid.
• Igneous rocks would be common around an old
  volcano.
• Flint, obsidian, and granite are examples of
  igneous rocks.

29
The Earths crust

• Metamorphic rocks form when one type of rock is
  exposed to extreme temperatures, and changes into
  another type of rock.
• Marble and Quartzite are metamorphic rocks.

30
The Earths crust

• The thickness of the earths crust varies
  depending on location.
• The crust at the bottom of the ocean (oceanic
  crust) is about 10 Km thick, but the crust above
  the continents, (continental crust) is about 32
  Km thick.

31
Atmosphere

• The atmosphere is the air that surrounds the
  earth. It rests on top of the crust.
• The atmosphere is
• 78 Nitrogen
• 21 Oxygen
• 1 Argon, Carbon Dioxide, Helium, Hydrogen,
  Xenon, and other trace gases.

32
Atmosphere

• The earths atmosphere goes about 100 Km above
  the earth, but ¾ of the atmospheres mass is
  within 11 Km of the earth.
• Atmospheric pressure at sea level is about 14.7
  psi.

33
Quiz Time!

• If the world were an atom, which parts would be
  each section of the earth?

34
Quiz Time!

• If the earth were a cell, which parts would be
  each section of the earth?

35
Quiz Time!

• If the earth were a peach, which parts would be
  each section of the earth?

36
Quiz Time!

• If the earth were an egg, which parts would be
  each section of the earth?