Pick one before you read on. It is fine to be wrong.
By the end you can
Show day and night with a lamp and a spinning ball
Explain why half of the Earth has day while half has night
Every place has day, then night, then day again. Why? The Sun is always shining. But it lights only half of the Earth at a time.
Draw it first
Draw the Sun lighting half of the Earth
1 Draw the Sun on the left. Draw three arrows of light going right. Write Sun.
2 Draw the Earth, a big ball on the right. Write Earth.
3 Draw a line down the middle. Shade the half away from the Sun.
The half of the Earth that faces the Sun has day. The Sun lights it.
The other half faces away from the Sun. No sunlight reaches it. There it is night.
The Earth does not stand still. It is always turning. To spin is to turn round and round, like a wheel.
The Earth makes one spin in about 24 hours. We call that time a day.
As the Earth spins, your place moves into the dark. Later it moves back into the light.
Seen from above the North Pole, one place goes through one day. It goes into the dark, then back into the light.The Earth from high above. Not to size. The arrow shows the spin.
Daytime is when your place faces the Sun. Night is when it faces away.
The Sun does not go away at night. Your place turns away from it.
See it three ways
As a picture
In words
The lamp is the Sun. The ball is the Earth. The mark is your place. Turn the ball, and the mark goes from light to dark.
In symbols
1 spin = about 24 hours = 1 day
Try it
Make day and night
You need: a torch or battery lamp, or a candle, a ball, an orange or a lump of clay, a pen, a room you can make dark.
Be safe: A grown up lights and holds any candle. Keep hair, cloth and paper away from the flame. Never shine a torch into anyone's eyes. Never use a lamp plugged into a wall socket. Never look at the Sun.
Draw a small mark on the ball with the pen. It is where you live.
Make the room dark. Put the lamp on a table, shining across the room.
Hold the ball in the light, a little way from the lamp.
Look at the ball. Which half is lit? Which half is dark?
Keep the lamp still. Turn the ball slowly, one full turn. Watch your mark.
What you will see: Half of the ball is lit. The other half is dark. As you turn it, your mark goes into the dark. Then it comes back into the light. The lamp does not move. One full turn is one day.
If you cannot try it, this is what happens.
A wrong idea many people have
Night comes when the Sun goes behind the hills.
Why it feels right: In the evening you watch the light sink behind hills or trees. Then it gets dark.
The test that breaks it: Use the lamp and the ball. The ball has no hills. Turn it, and the mark still goes dark. On flat land, the light on the ground fades at dusk. No hill is near. Never look at the Sun.
What is true: Night comes when your place turns away from the Sun. The Sun does not hide behind hills. Your place turns away from it.
Key words
spin
to turn round and round, like a wheel.
daytime
the time when your place faces the Sun.
night
the time when your place faces away from the Sun.
Back to your guess
The answer is A: The Earth spins, so each place turns away from the Sun.
The Earth spins. Your place turns toward the Sun, then away from it. When it faces away, it is night.
Check yourself
Try each one before you look. A wrong answer tells you where to go next.
What gives us day and night?
See the answer
The Earth spins
The Earth spins. Each place turns toward the Sun, then away.
If you chose A: The lamp stayed still in your model. The ball turned. The Earth spins.
If you chose B: The Moon does not cover the Sun every night. Night is the half turned away from the Sun.
Which half of the Earth has night?
See the answer
The half facing away from the Sun
No sunlight reaches the half that faces away. There it is night.
If you chose A: The half facing the Sun is lit. It has day.
If you chose C: The Moon does not make night. The half turned away from the Sun has night.
In the lamp model, what does the ball stand for?
See the answer
The Earth
The ball is the Earth. The lamp is the Sun. The mark is where you live.
If you chose B: The lamp is the Sun. It makes the light.
If you chose C: The Moon is not in this model. The ball is the Earth.
The Earth makes one spin in about 24 hours. How many hours do 2 spins take?
See the answer
48 hours
Each spin takes 24 hours. 2 times 24 is 48 hours. That is 2 days.
From an earlier chapter
Which one is a star that makes its own light?
See the answer
The Sun
The Sun is a star, a huge ball of hot, glowing gas. It makes its own light.
If you chose A: The Earth is a ball of rock. It is not a star. Go to S2.9.1.
If you chose B: The Moon is a ball of rock. It makes no light of its own. Go to S2.9.1.
Draw the Earth with the Sun on the left. Show the day half and the night half.
See the answer
A ball with the Sun on its left. The left half is day. The right half is shaded and is night.
The half that faces the Sun is lit. The half that faces away is dark.
It is night at your place. Where is the Sun?
See the answer
The Sun is shining on the other half of the Earth.
The Sun always lights one half of the Earth. At night your place is on the half turned away.
If you chose A: The Sun never goes out. It shines all the time. Your place has turned away from it.
If you chose B: In the model the lamp stayed still and the ball turned. The Earth turns. The Sun does not go round it.
If you chose C: The Moon hides the Sun only in an eclipse. That is rare and short. Night comes from the turning Earth.
Hana has a mark on the lit half of the ball. She turns the ball slowly, one whole turn. The lamp stays still. What does the mark do?
See the answer
It goes into the dark, then comes back into the light.
The turning ball carries the mark out of the light and back. On the Earth, one spin is one day and one night.
If you chose A: The lamp lights only half of the ball. Turning the ball moves the mark away from the light.
If you chose B: One whole turn brings the mark back into the light. Your place does this every day.
If you chose C: The lamp stays still. The ball turns, so the mark leaves the lit half.
Keep it
Copy this into your exercise book.
The Earth spins once in about 24 hours. The half facing the Sun has day. The half facing away has night. The Sun does not go away. Your place turns.
Draw: Draw the Sun and the Earth. Shade the half away from the Sun. Write day and night.
