Earth's Interior

 

 

 

Introduction

If you have ever eaten a jawbreaker candy, you know it looks different on the inside than it does on the outside.

In your science journal, complete and answer the following questions.

Look at the three objects and answer the questions.

1.  What do you think is inside each object?

2.  How do you know?

          

Now click on each image, then answer the question.

3.  Were you right about what was inside each object? Why or why not?

In this unit, you will explore the inside of Earth to learn about its different layers.

The Earth is made of various layers:

·      Crust à lithosphere

·      Mantle à lithosphere, asthenosphere, and mesosphere

·      Core à outer and inner

Earth's interior has three main layers: a thin, rocky crust; a thick, rocky mantle; and a metallic core. The measurements provided are averages.

Earth's interior has three main layers: a thin, rocky crust; a thick, rocky mantle; and a metallic core.

The measurements provided are averages.

 

Let's Practice – Earth's Layers

 

 

 

Inside Earth

Earth's Layers

 

Look at the image above and answer the following questions in your science journal.

1.  What are the three parts that make up the composition of Earth?

2.  What are the five layers that make up the physical structure of Earth?

People have always been curious about what is at the center of the Earth.

Some people have guessed that dinosaurs, strange creatures, or even aliens might be there. Others thought the center of the Earth could be a whole different world! In the late 1600s, the astronomer and geophysicist Edmond Halley said there is nothing at the center of Earth, just a hollow ball. Some Asian religions refer to a hollow area below Earth.

Scientists use different methods to find out what is at the center of Earth—and they have discovered that it is far from hollow.

They divide up the Earth in two ways:

 

Let's Practice:  The Layers of the Earth

 

 

Composition

 

 

There are three parts of the composition of Earth:  the crust, mantle, and core. 

        Crust

The outer shell of Earth is the crust. It is thin and hard. The crust comprises granite, silicon, basalt, aluminum, sodium, calcium, and potassium.

The crust stretches from just under Earth's surface to about 18 miles (30 km). This is where you find some of the lithospheres.

Crust temperatures are cooler than the other layers, about 392°-752° F (200-400° C).

It might seem like the crust is big—and it is—because this is the part that we can see. But the crust is only about 1% of the Earth. The mantle and core together make up the other 99%.

 

 

        Mantle

The mantle gets warmer the farther down you go, with temperatures from 572°-932° F (300°-500° C).

The mantle is very deep, stretching from 18 miles (30 km) to about 1,118-1,801 miles (1,800-2,900 km). This is where you find the part of the lithosphere closer to the center of Earth, the asthenosphere, and the mesosphere.

Oxygen makes up almost half of the mantle (45%). Nearly a fifth of the mantle is silicon, and nearly a quarter is magnesium. Other elements in smaller amounts include calcium, aluminum, potassium, iron, and sodium.

The mantle is denser than the crust because it has more magnesium and less aluminum.

 

        Core

The innermost layer of Earth is the core, which includes the outer and inner core.

The core is made of magnetic elements, mostly of iron with some nickel and probably silicon.

The core can get as hot as 12,632° F (7,000° C) and stretches from 1,800-3,958 miles (2,900-6,371 km). 

 

In your science journal, answer the following questions.

1.  What do we call the outer shell of the Earth?

2.  Which layer covers 80% of the Earth?

3.  What two elements make up the most of the core?

 

Let's Practice:  Structure of the Earth

Each of Earth's layers has different properties. Explore how the layers work together to create oceans, build mountains, and cause earthquakes and volcanoes.

Use the following if it prompts a username and password:  username:  jcesc   password:  student

Click the image below to begin.

 

Physical structure

 

 

There are five layers of Earth: the lithosphere, asthenosphere, mesosphere, outer core, and inner core.

        Lithosphere

Earth's outside layer, the lithosphere, includes the crust and part of the mantle. People live right above the lithosphere, which is the coolest layer. From the surface of the Earth, the temperature increases as you go down to the top of the asthenosphere, where it is about 2,336° F (1,280° C).

The lithosphere holds many useful materials, including oil, coal, and natural gases.

        Asthenosphere

Under the lithosphere, the asthenosphere goes down 62-434 miles (100-700 km) below Earth's surface. It is very hot (932° F or 500° C)—so hot that the rocks move around like slow liquid.

The asthenosphere has chemicals similar to the lithosphere, but it is soft instead of hard because the temperature is close to the melting point of rock.

This layer helps move and change the Earth's surface. Because the asthenosphere is soft, the lithosphere can move over it. The lithosphere sinks at subduction zones and pulls apart at tectonic boundaries, allowing the land and the sea floor to spread and rise.

        Mesosphere

Beneath the asthenosphere is the mesosphere. The mesosphere is about 434-1,800 miles (700-2,900 km) deep. This is the lowest part of the mantle.

The mesosphere is similar to the asthenosphere but gets even hotter (3,632° F or 2,000° C).

With all of Earth on top of it, the mesosphere is under so much pressure that the rocks are solid and move slower than they do in the asthenosphere.

        Outer Core

Before getting to the center of Earth, you must go through the outer core. It stretches from 1,800-3,200 miles (2,900-5,150 km) into Earth.

This core part is made of liquid iron and nickel and is very hot—9,032° F (5,000° C). The high temperature makes the iron and nickel melt into liquid.

Iron and nickel in the outer core are strong magnets. Scientists think this is why Earth has a magnetic field around it. Earth needs a magnetic field so that particles from space go around the planet instead of slamming into Earth—which could hurt living things. 

        Inner Core

The center of Earth is the inner core, which is hot: 12,632° F (7,000° C).

Iron and nickel make up the inner core, but they stay in solid form and do not melt even in the heat because of the huge amount of pressure deep inside Earth.

One reason Earth has such a hot core is that a lot of energy and heat were made when the planet first formed, and the energy and heat are still there.

Scientists think the inner core goes from 3,200-3,958 miles (5,151-6,371 km).

Because of so much pressure, heat, and miles to dig through, a real journey to the center of the Earth is impossible. 

In your science journal, answer the following questions.

1.              Which layer of Earth would you find oil and coal?

2.              Which layer helps move and change the Earth's surface?

3.              Which layer has solid rocks because of the pressure from the layers above it?

4.              Which layer do scientists think that the Earth has a magnetic field because of iron and nickel found on this layer?

5.              Which layer is impossible to go to because of the extreme heat and pressure?

 

Let's Practice:  Crust, Mantle, or Core