Book Three

Book Three

Reading Preview

1. Do you know what the sky is?

2. How do rockets work? 3. Have you ever dreamed to travel in space?

Book Three

Rockets in the Sky What is the sky? Where is it? How high is it? I’m

sure these questions are always asked by people.

They are very difficult to answer, aren’t they?

If someone asked you: “What color is the sky?” I

expect you would answer: “Blue.” I’m afraid you would

be wrong. The sky has no color. When we see blue,

we are looking at blue sunlight.

Book Three

Is the sky full of air? We know that there is air around the world. We could not breathe without air. Airplanes could not fly without air. They need air to lift their wings. Airplanes cannot fly very high because as they go higher, the air gets thinner. If we go far enough away from the earth, we find there is no air. Perhaps we can answer some of our questions now. What is the sky? Nothing. Where is it? It is all around the world. The sky is space. In this space there is nothing except the sun, the moon, and all the other stars.

Book Three

Let’s say something about the moon, which has been

greatly studied by the scientists. The moon is about

384,000 kilometers away from the earth. An airplane

cannot fly to the moon because the air reaches only 240

kilometers. Then there is no air. But there is something

that can fly even when there is no air. This is a rocket.

How does a rocket fly? If you want to know, get a

balloon and then blow it up until it is quite big. Do not

tie up the neck of the balloon. Let go! The balloon will fly

off through the air very quickly. The air inside the balloon

Book Three

tries to get out. It rushes out through the air. It doesn’t need wings like an airplane. This is how a rocket works. It is not made of rubber like a balloon. It is made of strong but light metal. There is gas inside the rocket. The gas is made very hot. When it rushes out of the end of the rocket, the rocket is pushed up into the air. Rockets can fly far out into space. Rockets with men inside them have already reached the moon. Several rockets without men have been sent to other worlds much farther away. One day they may be able to go anywhere in space.

Book Three

rocket：

object driven into

the air by an explosion

or by gas

Book Three

sunlight：

strong light of the sun

Book Three

breathe：

to take air into the lungs and

send it out again

Book Three

space：

what is above the surface of the earth

Book Three

kilometer：

1,000 meters

Book Three

balloon：

bag filled with gas to make it rise in

the air

Book Three

blow：

to send air quickly out of the mouth

Book Three

tie：

to fasten or bind (with string, rope,

wire, etc.)

Book Three

wing：

two large side pieces of an

airplane

Book Three

metal：

things such as iron, steel and gold