Gill
Science
Stage 4
S
To the Solar System and
beyond
Courtesy NASA/JPL-Caltech)
What is the structure of Earth?
S 43924
Number: 43924
Title: The Solar System
This publication is copyright New South Wales Department of Education and Training (DET), however it may contain
material from other sources which is not owned by DET. We would like to acknowledge the following people and
organisations whose material has been used:
Extract from Science Syllabus Years 7-10 © Board of Studies NSW, 2003
Unit overview pp iv-vii
Various photographs, courtesy of NASA/JPL-Caltech
Front cover and Part covers,
The Earth pp 3, 34
The Solar System pp 3, 6, 9,
19-23, 25, 34, 39, 44-45, 4750, 57-59, 61, 66-67
The Universe p 36
Photograph of Weathering and Erosion in the Desert ©Rhonda Caddy
Photograph of a Glacial Valley ©Upgrade Business Systems
Photograph of the Crab Nebula ©Malin/Pasachoff/Caltech
Photograph of a Star ©Anglo-Australian Observatory
Photograph of Stars ©Anglo-Australian Observatory/Royal Observatory, Edinburgh
The Earth p 18
The Earth p 19
The Universe p 7
The Universe p 8
The Universe p 35
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What is the structure of Earth?
Before you begin this lesson, here is a very important question.
Have you read ‘What resources can you use?’ in the introductory
section? If you haven’t, do it now! It may change what you do in this
lesson.
What is the task?
In the send-in exercise for this lesson, you will answer this question,
‘What is the structure of Earth?’.
Your answer must describe what is inside the Earth as well as what
covers the surface and surrounds it.
Here are some terms that you should investigate.
Earth
lithosphere
biosphere
core
crust
atmosphere
mantle
hydrosphere
How should you answer?
However you decide to present the information, make sure that it answers
the question.
The Earth
5
If you have decided to use this booklet to find an answer, complete the
rest of this lesson.
The surface of Earth
Look around you. What do you see? There are many different things
over the surface of planet Earth.
These things can be classified (put into groups) in different ways. One
classification system that scientists use sorts things into the biosphere,
lithosphere, hydrosphere and atmosphere.
The word sphere in each of these names describes the shape of Earth.
The term refers to all similar objects anywhere on our ball-shaped planet.
(Other planets can be described in this way too.)
The surface of Earth
Bio means life. So, biosphere refers to all the living things on Earth.
Litho means rock. The lithosphere can also include materials that are
made from rocks, such as soil, buildings and metal objects.
Hydro means water. So, the hydrosphere is all the water on Earth.
Water on Earth exists as solid, liquid and gas form.
Where on Earth would you find water as a:
a
solid?
_______________________________________________________
b
liquid?
_______________________________________________________
c
gas?
_______________________________________________________
Did you suggest that solid water is ice or snow, liquid water is the oceans
and rivers, and water as a gas would be water vapour in the air?
Water vapour in the air is usually considered part of the atmosphere.
The atmosphere includes all the gases that surround our planet.
6
To the Solar System and beyond
Now look at the drawing below. Use coloured pencils to shade the
drawing to match the key below.
Colour
Part of Earth’s surface
pink
biosphere
brown
lithosphere
green
hydrosphere
blue
atmosphere
Check your answers.
The Earth
7
Inside Earth
Earth is not just a huge ball of rock. Here is a diagram showing the inner
structure of Earth.
Inside Earth
Use information from the diagram to complete these descriptions of the
parts inside Earth.
•
Earth’s centre is called the __________________. It is made of two
heavy elements called iron and nickel that sank to the middle as Earth was
forming. There is a solid centre surrounded by a molten (melted) layer.
•
Earth’s surface is called the ______________ . It is the rocky layer that
makes up landmass and the floors of oceans. It is a thin layer composed
mostly of light elements such as silicon, aluminium and oxygen.
•
Between the core and the crust is the ______________ . It is also made
of lighter elements combined into rocks. The top part of this layer and the
crust together form the _________________________ .
Check your answers.
8
To the Solar System and beyond
The diagram below is called a cross-section because it is as though Earth
has been cut (or sectioned) through the middle.
Diagram of Earth
Put these labels on the diagram below.
solid inner core
liquid outer core
solid mantle
solid crust
Now, add this information to your diagram.
•
The radius of the inner core is about 1200 km.
•
The outer core is about 2300 km thick.
•
The mantle is about 2800 km thick.
•
The crust is between 6 and 40 km thick.
Check your diagram.
The Earth
9
Thinking of a model
The diagrams of Earth that you have used in this lesson are models.
Models are ways of presenting information to help you understand it.
Another model for the structure of Earth
Earth is a cream and jam-filled doughnut. The lump of cream in the
centre is the solid inner core of iron and nickel. Around this is the runny
jam of molten iron and nickel. Then, there is the doughy part of the
doughnut, solid but soft too. On the outside is the crunchy, sugary crust.
1
How does this model help you to remember the structure of Earth?
_______________________________________________________
_______________________________________________________
2
There are several ways that this model does not help you understand
what the parts inside Earth are like. What are some problems with
this model?
_______________________________________________________
_______________________________________________________
_______________________________________________________
Check your answers.
Complete Exercise: What is the structure of Earth?
10
To the Solar System and beyond
Suggested answers
Check your responses against these suggested answers.
The surface of Earth
The biosphere contains all the living things, trees, bushes, grass, birds and
dragonfly. The lithosphere is the rocks. You might also include the city in the
background if you think of it as made from rocks. For the hydrosphere, you
should have shaded the stream and perhaps the clouds in the sky.
The atmosphere is the rest of the sky.
Inside Earth
•
Earth’s centre is called the core.
•
Earth’s surface is called the crust.
•
Between the core and the crust is the mantle. It is also made of lighter
elements combined into rocks. The top part of this layer and the crust
together form the lithosphere.
Diagram of Earth
The Earth
11
Another model for the structure of Earth
12
1
This model helps to remember the structure of the Earth because it uses a
familiar object to describe an unfamiliar object.
2
Here are some problems with the model.
•
A doughnut isn’t a sphere. It is squashed.
•
The cream isn’t always in the middle and it isn’t always surrounded
by jam.
•
The cream and jam are both made of nickel and iron so they probably
should be the same colour.
•
The mantle isn’t really doughy or spongy; it is solid rock with areas
that are molten.
To the Solar System and beyond
Exercise: What is the structure of
Earth?
Name
____________________________
Teacher ____________________________
Your answer must describe what is inside Earth as well as what covers it
and surrounds it.
Your answer should show that you can:
•
identify the lithosphere, hydrosphere and atmosphere
•
identify the core, mantle, and crust
•
describe each of these parts of Earth.
Attach your own send-in exercise and answer or complete the task.
Cut out the boxes below. Match each box with a part of the diagram on
the following page. Paste it into position. Add the missing names.
The Earth
The outer layer of Earth
is made of light
elements, rocks
The atmosphere refers
to the gases that
surround the Earth
The central part is made
from solid iron and nickel
whereas the outer part is
molten iron and nickel.
The hydrosphere refers
to all parts of Earth with
water.
A thick layer of rock.
The top part of this layer
and the crust form the
lithosphere
13
14
To the Solar System and beyond