To the Solar System and beyond

Transcription

1 Science Stage 4 Gill S To the Solar System and beyond What is the structure of Earth? Courtesy NASA/JPL-Caltech) S 43924

2 Number: 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 Various photographs, courtesy of NASA/JPL-Caltech Unit overview pp iv-vii Front cover and Part covers, The Earth pp 3, 34 The Solar System pp 3, 6, 9, 19-23, 25, 34, 39, 44-45, 47-50, 57-59, 61, The Universe p 36 Photograph of Weathering and Erosion in the Desert Rhonda Caddy The Earth p 18 Photograph of a Glacial Valley Upgrade Business Systems The Earth p 19 Photograph of the Crab Nebula Malin/Pasachoff/Caltech The Universe p 7 Photograph of a Star Anglo-Australian Observatory The Universe p 8 Photograph of Stars Anglo-Australian Observatory/Royal Observatory, Edinburgh The Universe p 35 COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you on behalf of the New South Wales Department of Education and Training (Centre for Learning Innovation) pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. CLI Project Team acknowledgement: Writer(s): Illustrator(s): Project Manager(s): Editor Desktop Publisher Sue Doolan, Rhonda Caddy, Jane West Barbara Gurney, Sue Doolan Julie Haeusler Julie Haeusler Alide Schimke All reasonable efforts have been made to obtain copyright permissions. All claims will be settled in good faith. Published by Centre for Learning Innovation (CLI) 51 Wentworth Rd Strathfield NSW 2135 Copyright of this material is reserved to the Crown in the right of the State of New South Wales. Reproduction or transmittal in whole, or in part, other than in accordance with provisions of the Copyright Act, is prohibited without the written authority of the Centre for Learning Innovation (CLI). State of New South Wales, Department of Education and Training 2005.

3 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

4 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

5 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

6 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

7 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

8 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

9 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

10 Another model for the structure of Earth 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. 12 To the Solar System and beyond

11 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 outer layer of Earth is made of light elements, rocks The central part is made from solid iron and nickel whereas the outer part is molten iron and nickel. The atmosphere refers to the gases that surround the Earth 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 The Earth 13

12 14 To the Solar System and beyond