One of our finest human qualities is our tendency to wonder about things. Students of the natural sciences are encouraged to wonder about the things they see about them.

When last did you wonder about something? Have you ever wondered about the sun? The stars? The universe and where it ends? Whether there are other planets on which there may be life?

When last did you look at the starry skies? Do it again tonight and while you are looking, remember to wonder about that which you can see as well as that which you cannot see:

The stars that you see are suns – they are just much further away from us than our own sun.

We are able to see the stars because they radiate light. It takes the light billions of years to reach us here on earth.

The universe is made up of millions of galaxies.

Each galaxy consists of a great number of solar systems.

The most visible part of the galaxy of which our solar system is part, is the Milky Way.

Of all the stars our sun is the star that is the closest to the earth. It consists of a ball of burning gases that radiate light and heat. It is more than 300 000 times the size of the earth.

Our earth is one of nine planets that revolve around the sun. It is the only planet that we know of that has life. The other nine planets are (from the closest to the furthest from the sun):

Figure 1

The course or “path” of a planet around the sun is called its orbit.

Many planets have moons that revolve around them. Our earth also has its own moon. The moon does not “shine”, but because the sun shines on it, the moon appears to emit light.

QUESTIONS:

1. Why can we say that the earth is a planet?

2. Which two planets are closest to the earth?

3. Which planet is closest to the sun?

4. Why don’t we call the moon a star?

5. The circle below represents the earth. Draw an orbit for the moon as you imagine it to be. Indicate the moon as well.

Figure 2

The earth revolves around its own imaginary axis continuously. This imaginary axis lays more or less North-South (from the North Pole to the South Pole). We call this action the rotation of the earth.

Figure 3

Each rotation of the earth around its own axis takes 24 hours and that is why there is a day and a night in each 24 hours.

Day: the condition on that part of the earth that faces the sun.

Night: the condition on that part of the earth that faces away from the sun.

Figure 4

As the day progresses from early morning until 12 noon, it seems as if the sun is moving upwards in the sky, but of course it is the earth that is moving. In the afternoon it appears as if the sun is going down (setting)

LEARNING OTCOMES (LOs)

LO 1

SCIENTIFIC INVESTIGATION

Learners respond confidently to their desire to learn about natural phenomena; they investigate relationships and solve problems within the context of science, technology and the environment.

ASSESSMENT STANDARDS (ASs)

We know this when the learner:

LEARNING OTCOMES (LOs)

LO 2

CONSTRUCTION OF SCIENTIFIC KNOWLEDGE

Learners know, interpret and apply scientific, technological and environmental knowledge.

ASSESSMENT STANDARDS (ASs)

We know this when the learner:

2.1 recalls significant information;

2.2 categorises information.

LEARNING OUTCOMES (LOs)

LO 3

SCIENCE, TECHNOLOGY AND THE ENVIRONMENT

Learners are able to show understanding of the underlying connections of technology, the community and the environment.

ASSESSMENT STANDARDS (ASs)

We know this when the learner:

3.1 understands science and technology in the context of history and personal knowledge;

3.2 understands the impact of science and technology.

Our Earth: The Living Planet

Allow ample time for informal class discussions on the wonder of everything and our right to wonder about things.

QUESTIONS:

An elliptical orbit that is orientated approximately 5 degrees to earth's equator. The moon's diameter is one quarter that of the earth. The distance between the earth and the moon is 30 times the diameter of the earth.

This just for interest's sake: