23

CLIL Earth Sciences

The EarthThe Earth is the third planet from the Sun in the solar system and the fifth largest. Its diameter is approximately 12,700 km and it is about 4.5 billion years old. Earth is a terrestrial planet, which means it is made mostly of rock and metal, and it has a very high density. A terrestrial planet also has a slow rotation, a solid surface, no rings and not many satellites. Mercury, Venus and Mars are also terrestrial planets. Earth is different from other terrestrial planets because its crust is divided into separate solid plates, which float on top of the hot mantle below. The name that describes this process is plate tectonics. The surface of the Earth is divided into approximately twelve large plates and many small ones. A plate boundary is where one plate meets another. Mountains, ocean trenches, volcanoes, and earthquakes all occur on plate boundaries. Approximately 71% of the Earth’s surface is water. Earth is the only planet in the solar system where water exists in a liquid form on the surface. Liquid water is essential for life as we know it. The Earth’s atmosphere is 77% nitrogen, 21% oxygen and 2% other gases such as carbon dioxide. The Earth has one satellite – the Moon. The gravitational forces

between the Earth and the Moon slow the Earth’s rotation by about 2 milliseconds per century. This means that 900 million years ago there were 481 18-hour days in a year!

5

10

15

Vocabulary 3 Find the English translations for these words

in the text.

1 superficie (L.07) 2 placche (L.12) 3 galleggiano (L.12) 4 margine (L.16) 5 terremoti (L.18) 6 secolo (L.27)

Check 4 Answer the questions.

1 What is a terrestrial planet?

2 How many terrestrial planets are there in the solar system?

3 What is the process of plate tectonics?

4 What occurs where two plates meet?

5 Why is the Earth unique in the solar system?

6 In the past there were more than 365 days in a year. Why?

Listening 5 a T4 20 Listen to an astronaut describing

the view of Earth from space. Tick 4 the things you can see from space.

deserts continents airports large cities houses clouds roads people cars the Pyramids

b T4 21 Listen. What can’t you see from the Moon (which is further away)?

c In pairs. Check your answers.

A What can you see from space?

B You can see…

Writing Portfolio

6 Write a short description (75–100 words) of an astronaut’s view of the Earth from space. Use exercise 5 to help you. Include this information:

natural and man-made objects you can see

the colours you can see

a famous visible object you would like to see from space

Planet Earth

Warm-up

1 How much do you know about planet Earth? In pairs. Decide if these statements are true or false. Write T or F.

1 The Earth is the third planet from the Sun.

2 The Earth is the second largest planet in the solar system.

3 The Earth is about 4.5 billion years old.

4 89% of the Earth is covered in water.

5 The Earth’s atmosphere is 77% oxygen.

Reading 2 Read the description of the Earth and check

your answers to exercise 1.

2

20

25

DT Think English CB1 3P.indd 23 13/4/10 16:01:13