Earth, Sun and Moon. Attnom Academy

S2.9.1 Chapter 1

Sun, Earth and Moon

What are the Sun, the Earth and the Moon?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The Sun and the Moon are the same size.
You picked A. Read on. At the end, the chapter comes back to your guess.
B All three are balls. Only the Sun makes its own light.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The Sun and the Moon are both stars.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain the Sun is a star, and Earth and Moon are balls
Model the sizes of the Sun, Earth and Moon with round objects

Three big things shape our days and nights. They are the Sun, the Earth and the Moon. You live on the Earth.

The Sun is a star. A star is a huge ball of very hot, glowing gas. Gas is stuff like the air. You cannot hold it.

The Sun makes its own light and heat. It is the star nearest to us. The stars you see at night are like our Sun. They are far, far away.

The Sun is a star. The other stars look like dots because they are so far away. Not to size.

The Earth is a ball of rock. It has water and air round it. The Earth is not a star. Its daylight comes from the Sun.

The Moon is a smaller ball of rock. It has no air. The Moon makes no light of its own. Sunlight lands on it and lights it up.

To reflect is to send light back. The Moon reflects sunlight. So does the Earth.

Only the Sun makes light. The Earth and the Moon send some of it back. Not to size.

Draw it first

Draw the Sun, Earth and Moon

1 Draw a big ball on the left for the Sun. Write Sun.
2 Draw a smaller ball for the Earth. Draw a tiny one for the Moon. Write both names.
3 Draw an arrow from the Sun to the Earth. Draw one to the Moon. Write not to size.

This picture is not to size. The real Sun is much, much bigger.

The Sun is about 109 times as wide as the Earth. The Earth is about 4 times as wide as the Moon.

About four Moons side by side are as wide as the Earth.

You can show this with a model. A model is a small copy of something big.

See it three ways

As a picture

In words

The Sun is a star. It makes its own light. The Earth and the Moon are balls of rock.

In symbols

Sun = 109 Earths wide. Earth = 4 Moons wide.

Say the Earth is a pea, 1 cm wide. Then the Moon is a seed, about 3 mm wide. Hold the seed 30 cm from the pea.

The Sun is then a ball about 1 m wide. It is more than 100 m away.

Try it

Make a model of the Sun, Earth and Moon

You need: a pea or a small bean, about 1 cm wide, a grain of rice or a tiny seed, a ruler or a sheet of writing paper, a string 50 cm long, a stick, flat ground outside.

Be safe: Never look at the Sun while you work outside. Look only at the ground. Never put the pea or the seed in your mouth.

Put the pea on a flat place. It is the Earth.
Measure 30 cm from the pea. A sheet of writing paper is about 30 cm long. Put the rice there. It is the Moon.
Go outside. Tie the stick to one end of the string.
Hold the other end on the ground. Pull the string tight.
Walk the stick round and scratch a circle on the ground. It is 1 m wide. It is the Sun.
Walk away from the circle. Count 200 steps. That is about 100 m. The real distance is a little more.

What you will see: The pea is tiny beside the Sun circle. The seed is even smaller, and close to the pea. The Sun is huge and very far away.

If you cannot try it, this is what happens.

A wrong idea many people have

The Sun and the Moon are the same size.

Why it feels right: In the sky, the Sun and the Moon look the same width.

The test that breaks it: Far things look small. Hold up your thumb at arm's length. Cover a house or a tree far away. The big thing looks smaller than your thumb. Look only at things on the ground, never at the Sun.

What is true: The Sun is about 400 times as wide as the Moon. It is also about 400 times as far away. So they look alike.

Key words

star: a huge ball of hot, glowing gas that makes its own light. The Sun is a star.
gas: stuff like the air. You cannot hold it.
model: a small copy of something big.
reflect: to send light back.

Back to your guess

The answer is B: All three are balls. Only the Sun makes its own light.

All three are balls. The Sun is a star and makes its own light. The Moon makes none.

Keep it

Copy this into your exercise book.

The Sun is a star, a huge ball of hot glowing gas. It makes its own light. The Earth and the Moon are balls of rock. The Sun is 109 Earths wide. The Earth is 4 Moons wide.

Draw: Draw a big ball, a small ball and a tiny ball. Write Sun, Earth and Moon.

S2.9.2 Chapter 2

Why we have day and night

Why does it get dark at night?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The Earth spins, so each place turns away from the Sun.
You picked A. Read on. At the end, the chapter comes back to your guess.
B The Sun goes behind the hills.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The Moon covers the Sun every evening.
You picked C. Read on. At the end, the chapter comes back to your guess.

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.

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.

S2.9.3 Chapter 3

The Sun seems to move

Why does the Sun seem to cross the sky?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The Sun rises in the west and sets in the east.
You picked A. Read on. At the end, the chapter comes back to your guess.
B The Sun goes round the Earth every day.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The Earth turns, so the Sun seems to cross the sky.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain why the Sun seems to cross the sky east to west
Find east and west with a stick and two shadow marks

Watch the shadows on the ground through a day. Early in the day, they are long. At midday, they are short. Late in the day, they are long again.

Long shadows mean the Sun is low. Short shadows mean the Sun is high. So the Sun climbs, and then it sinks.

Draw it first

Draw a stick and its shadow through the day

1 Draw a stick. East is on the right. Draw the Sun low on the right. Draw a long shadow on the left. Write morning.
2 Draw the Sun high above. Draw a short shadow at the foot. Write noon.
3 Draw the Sun low on the left. Draw a long shadow on the right. Write evening.

Almost everywhere on Earth, the Sun rises roughly in the east. It crosses the sky. It sets roughly in the west.

Most days it rises to the north or south of east. Roughly east is good enough to find your way.

Here you face north. If you face south, east is on your left.

Where the Sun stands at midday depends on your place. Far north of the equator, it stands in the south. Far south of the equator, it stands in the north. Near the equator, it can be almost overhead.

The Sun is not really crossing the sky. The Earth is turning. It turns toward the east. You turn with it.

Seen from above the North Pole. The Earth turns. A place at the top turns into the light. A place at the bottom turns into the dark. Not to size.

Think of a bus. You ride east. A tree by the road is still. But the tree seems to go back, toward the west.

See it three ways

As a picture

In words

On a bus, you ride east. The tree seems to go west. The Earth turns east, so the Sun seems to go west.

In every place, the Sun seems to move from east to west.

A shadow points away from the Sun. As the Sun seems to move west, the shadow tip moves east.

So a stick can find east and west for you. You need no compass.

Two more directions help. Face east. North is on your left. South is on your right.

Face east. North is on your left. South is on your right.

Try it

Find east and west with a stick

You need: a straight stick, as long as your arm, two stones, flat ground in the sun, with no shade, a sunny morning or afternoon, a clock, or a task that takes 20 minutes.

Be safe: Never look up at the Sun to check. Look only at the shadow on the ground. Wash your hands after you touch soil.

Push the stick upright into the ground. Check that it does not lean.
Look at its shadow on the ground. Put a stone at the tip of the shadow. Call it stone 1.
Wait about 20 minutes. Do not look at the Sun. The shadow moves.
Put the second stone at the new tip of the shadow. Call it stone 2.
Stand on the line between the stones, in the middle.
Turn so stone 1 is on your left. Stone 2 must be on your right.

What you will see: Stone 1 is west. Stone 2 is east. The line between the stones runs east and west. You now face roughly north. South is behind you. The stones need not line up with the stick. Only the line between them counts. The stones may lie north or south of the stick. It depends on where you live and the time of year.

If you cannot try it, this is what happens.

Now draw a line through the stick, across the stone line. Make the lines meet at a right angle. A right angle is a square corner, like on a book. That line through the stick runs north and south.

A wrong idea many people have

The Sun goes round the Earth every day.

Why it feels right: You see the Sun climb, cross and sink. You feel nothing move.

The test that breaks it: Ride in a smooth bus, cart or train. Look at a tree beside the road. The tree seems to go back. It is still. Or stand in a room and turn slowly. The lamp seems to swing past. It is you who move.

What is true: The Earth turns. We turn with it. So the Sun seems to move. It does not go round us each day.

Key words

east: the direction where the Sun seems to rise. The Earth turns toward the east.
west: the direction where the Sun seems to set.
north: the direction on your left when you face east.
south: the direction on your right when you face east.

Back to your guess

The answer is C: The Earth turns, so the Sun seems to cross the sky.

The Earth turns toward the east. So the Sun seems to rise in the east. It seems to set in the west.

Keep it

Copy this into your exercise book.

The Earth turns toward the east. So the Sun seems to rise in the east. It seems to set in the west. A shadow stick finds them. Stone 1 is west. Stone 2 is east.

Draw: Draw a stick, two stones and a dashed line through them. Write west and east.

S2.9.4 Chapter 4

A year: going round the Sun

What is a year? Why does a year sometimes have an extra day?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A A year is how long the Sun takes to cross the sky.
You picked A. Read on. At the end, the chapter comes back to your guess.
B A year is one trip of the Earth round the Sun.
You picked B. Read on. At the end, the chapter comes back to your guess.
C A year is one trip of the Moon round the Earth.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain the Earth takes about 365 days to go round the Sun
Explain why every fourth year has an extra day
Explain that distance from the Sun does not make seasons

You know that one spin of the Earth makes a day. But the Earth also travels. It moves round the Sun in a big circle.

An orbit is the path of one thing round another. The Earth moves round the Sun in an orbit.

One trip round the Sun is one year.

One spin of the Earth is a day. One trip round the Sun is a year.

Draw it first

Draw the Earth going round the Sun

1 Draw the Sun in the middle of the page. Write Sun.
2 Draw a big ring round the Sun for the path. Add an arrow along it.
3 Draw a small ball on the ring. Write Earth. Write one trip = one year.

This picture is not to size. The real path is much bigger.

The Earth moves very fast. But it moves smoothly, so you cannot feel it.

The trip takes about 365 and 1/4 days. That is a year.

A calendar uses whole days. A calendar year has 365 days. The extra quarter of a day does not fit.

A quarter of a day is about 6 hours. Each year, the calendar is 6 hours short.

The spare quarters add up. Four quarters make one whole day. After four years, we add one extra day.

See it three ways

As a picture

In words

Each year is a quarter of a day longer than the calendar. Four quarters make one whole day. So we add a day almost every fourth year.

In symbols

1 year = 365 and 1/4 days. 4 × 1/4 = 1 day.

A leap year has 366 days. Almost every fourth year is a leap year. All the other years have 365 days.

In a leap year, the extra day makes 366 days.

Try it

Add up the quarter days

You need: a sheet of paper, a pen.

Be safe: Tear the paper. Do not use scissors. Never look at the Sun.

Fold the paper in half. Fold it in half again the same way. Open it out.
Tear the sheet along the folds. You have four equal pieces.
Write year 1 to year 4, one on each piece.
Each piece is the quarter day that one year leaves over.
Put the four pieces side by side to make the whole sheet.

What you will see: One piece is a quarter of the sheet. Four pieces make the whole sheet. In the same way, four spare quarter days make one whole day.

If you cannot try it, this is what happens.

The year also brings seasons. A season is a part of the year with its own weather.

Many places have a warm season and a cold season. Near the equator there is little winter or summer.

The Earth leans a little to one side. It goes round the Sun. It always leans the same way.

So for part of the year the north leans toward the Sun. For the rest of the year the south leans toward it.

The half that leans toward the Sun has its warm season.

The Earth always leans the same way. On one side of its path the north leans toward the Sun. Half a year later the south does. Not to size.

A wrong idea many people have

Every year has exactly 365 days.

Why it feels right: A calendar has 365 days, and most years do too.

The test that breaks it: Look at the calendars of four years in a row. Count their days. Almost always, three have 365 and one has 366. The paper pieces show why.

What is true: A year is about 365 and a quarter days. So almost every fourth year has an extra day, a leap year.

A wrong idea many people have

Summer comes when the Earth is nearer the Sun.

Why it feels right: A fire feels hotter when you stand nearer to it.

The test that breaks it: The north is warm while the south is cold. Both halves of the Earth are the same distance from the Sun.

What is true: The Earth leans. The half that leans toward the Sun is warmer. Near the equator there is little winter or summer.

Key words

orbit: the path of one thing round another.
year: one trip of the Earth round the Sun. It takes about 365 and a quarter days.
leap year: a year with 366 days. It comes almost every fourth year.
seasons: parts of the year with their own weather.

Back to your guess

The answer is B: A year is one trip of the Earth round the Sun.

A year is one trip of the Earth round the Sun. It takes about 365 and 1/4 days. The quarters add up to an extra day.

Keep it

Copy this into your exercise book.

One trip round the Sun takes about 365 and a quarter days. That is a year. The spare quarters add up to one day. So almost every fourth year has 366 days.

Draw: Draw the Sun and a ring round it. Put the Earth on the ring. Write one year.

S2.9.5 Chapter 5

The Moon goes round the Earth

Where does the Moon go, and why does it shine?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The Moon makes its own light and stays still.
You picked A. Read on. At the end, the chapter comes back to your guess.
B The Moon goes round the Earth and shines with sunlight.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The Moon is a small Sun that goes away by day.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain that the Moon goes round the Earth about once a month
Explain that the Moon shines because it reflects sunlight

The Moon is a ball of rock. It is much smaller than the Earth. It has no air.

The Moon is not still. It goes round the Earth. The path of one thing round another is its orbit.

The Moon goes round the Earth once in about a month. Full Moon to full Moon takes about 29 and a half days. Our word month comes from Moon.

The Moon makes no light of its own. Sunlight lands on it. Some of it bounces off. That bounced light is what you see. We say the Moon reflects sunlight.

Draw it first

Draw the Moon on its orbit

1 Draw the Earth in the middle. Write Earth.
2 Draw a ring round it. Put the Moon on the ring. Write Moon. Add an arrow on the ring.
3 Draw the Sun on the left. Draw arrows of sunlight to the Earth and the Moon.
4 Draw an arrow from the Moon to the Earth. Write moonlight.

The picture is not to scale. In real life the Moon is far from the Earth. The Sun is much further away.

The Sun always lights the half of the Moon that faces it. The Moon is like a pale stone in a torch beam.

Sunlight bounces off the Moon's lit side and reaches your eye. Not to size.

The Moon turns as it goes round. So the same side always faces us. From the Earth we never see the other side.

See it three ways

As a picture

In words

Start at a full Moon. Each week the Moon goes about a quarter of the way round. After about 29 and a half days it is full again.

You can often see the Moon in the day. The sky is bright then, so the Moon looks pale.

A half Moon in the day sky. Its lit side faces the Sun. Never look at the Sun.

Try it

Be the Earth, and let a friend be the Moon

You need: a friend, a ball, or a stone wrapped in paper, a pen, a clear floor.

Be safe: Walk slowly and keep the floor clear. Do this indoors, away from the Sun.

Draw a mark on the ball. This mark is the side of the Moon that faces us.
Stand in the middle of the floor. You are the Earth.
Your friend holds the ball. The mark must always face you.
Your friend walks slowly round you in a circle. The mark keeps facing you.
Watch the ball. Can you ever see the back of it?

What you will see: You never see the back of the ball. Your friend turns round once while walking round you once. The Moon does the same. So we always see the same side of the Moon.

If you cannot try it, this is what happens.

A wrong idea many people have

The Moon comes out only at night.

Why it feels right: We notice the Moon most when the sky is dark. It looks brightest then.

The test that breaks it: For a week, look at the morning and afternoon sky. Look away from the Sun. On some of those days you will see a pale Moon. Never look near the Sun to find it.

What is true: The Moon is in the sky by day too. The daylight makes it look pale.

Key words

orbit: the path of one thing round another.
month: about the time the Moon takes to go round the Earth once.
reflect: to send light back.

Back to your guess

The answer is B: The Moon goes round the Earth and shines with sunlight.

The Moon goes round the Earth about once a month. It makes no light. It shines because sunlight bounces off it.

Keep it

Copy this into your exercise book.

The Moon goes round the Earth once in about a month. It makes no light of its own. It shines because sunlight bounces off it. The same side always faces us.

Draw: Draw the Earth with a ring round it. Put the Moon on the ring. Draw the Sun and an arrow to the Moon.

S2.9.6 Chapter 6

Phases of the Moon

Why does the Moon change shape?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The Earth's shadow covers part of it.
You picked A. Read on. At the end, the chapter comes back to your guess.
B The Moon really grows and shrinks.
You picked B. Read on. At the end, the chapter comes back to your guess.
C We see more or less of its lit half.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Model the phases of the Moon with a ball and a lamp
Draw the Moon each night for two weeks and name the phases
Explain why the Moon looks upside down in the other hemisphere

Some nights the Moon is a thin curve. A week later it is a half circle. Later it is a full circle. How can this be?

The Moon does not change. It is always a ball.

The Sun always lights half of the Moon. A torch lights half of a ball in the same way.

The Moon goes round the Earth. So each night we look at it from a new place. We see more or less of the lit half.

Draw it first

Draw why the Moon changes shape

1 Draw the Sun on the left and the Earth in the middle. Draw a ring round the Earth.
2 Draw the Moon in four places on the ring. Draw a line down the middle of each.
3 Draw sunlight reaching each Moon from the left. Shade the half that faces away from the Sun.
4 Write each name: new, half growing, full, half shrinking. Add an arrow on the ring.

Look at the Moon on the left. It is between the Earth and the Sun. Its lit half faces the Sun. We see the dark half. We cannot see this Moon. It is a new Moon.

The Moon on the right is far from the Sun. The Earth is between them. We see its whole lit half. It is a full Moon.

At the top and bottom the Moon looks half lit. Between new Moon and half Moon, we see a thin curve. A thin curve is a crescent.

The shape we see each night is a phase. The phases go round and round.

See it three ways

As a picture

In words

The Moon grows from new to full in about two weeks. Then it shrinks back to new in about two more.

Make a Moon diary. Start on the first evening you can see a thin Moon.

Look at the Moon at about the same time each clear evening. Draw it in a circle. Shade the dark part. Do this for two weeks.

If clouds hide the Moon, leave that circle empty. After full Moon, it rises later each night. Look a little later.

Write the name under each drawing. Use new Moon, crescent, half Moon, over half and full Moon.

One page of a Moon diary. Each circle is one evening.

Try it

Make the phases with a ball and a torch

You need: a torch, a pale ball, or a stone wrapped in white paper, a room you can make dark, a shelf or chair for the torch.

Be safe: Never shine the torch into anyone's eyes. Never look at the Sun. Do this indoors with a torch only.

Stand the torch on a shelf and switch it on. Make the room dark.
Stand a few steps from the torch. Hold the ball high at arm's length.
Face the torch. Look at the ball. The lit side faces away from you.
Turn slowly to your left. Stop at each quarter turn.
At each stop, draw the lit part in a circle.

What you will see: The lit part of the ball changes as you turn. First you see a dark ball. Then half is lit. Then the whole near side is lit. Then half again. The torch always lights half of the ball.

If you cannot try it, this is what happens.

People in the north and in the south see the same Moon. But they see it turned round.

North and south are opposite ends of the Earth. People there have their heads pointing opposite ways. So they see the Moon turned half way round.

In the north, a growing Moon is lit on the right. In the south, it is lit on the left.

The same phases, seen from the north and the south.

Near the equator, a thin Moon can lie on its back. It looks like a boat.

Turn a picture of the Moon upside down. You see the Moon as people in the other half see it.

A wrong idea many people have

The phases of the Moon are the Earth's shadow on the Moon.

Why it feels right: The dark part of the Moon looks like a shadow.

The test that breaks it: In the ball and torch test, you hold the ball high. Your head makes no shadow on it. The ball still goes through every phase. So no shadow is needed.

What is true: The Sun always lights half of the Moon. We see more or less of the lit half. The Earth's shadow falls on the Moon only in an eclipse.

Key words

phase: the shape of the lit part of the Moon that we see.
new Moon: the Moon between us and the Sun. Its lit half faces away from us.
full Moon: the Moon on the far side of the Earth. We see its whole lit half.
crescent: a thin curved shape.

Back to your guess

The answer is C: We see more or less of its lit half.

The Moon is always a ball. The Sun lights half of it. We see more or less of that half.

Keep it

Copy this into your exercise book.

The Moon is always a ball. The Sun lights half of it. As it goes round, we see more or less of that half. These are its phases. North and south see it upside down.

Draw: Draw the Sun, the Earth and a ring. Put the Moon on the ring in four places. Shade the half of each Moon that faces away from the Sun.

S2.9.7 Chapter 7

Eclipses

Why does the Sun sometimes go dark in the day?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The Sun is switched off for a while.
You picked A. Read on. At the end, the chapter comes back to your guess.
B The Moon passes in front of the Sun.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The Earth's shadow covers the Sun.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain how the Moon blocks the Sun's light in an eclipse
Make a pinhole viewer. Watch an eclipse facing away from the Sun
Explain how the Earth's shadow causes an eclipse of the Moon

Sometimes the day goes dim. Sometimes the Moon turns dark red. Nothing is wrong. These are eclipses.

An eclipse is when one ball is in the shadow of another.

The Sun is the lamp. The Moon and the Earth are balls. Each ball has a shadow on the side away from the Sun.

The Moon can pass between the Sun and the Earth. Then the Moon blocks the Sun's light. This is an eclipse of the Sun. Its other name is a solar eclipse.

Draw it first

Draw an eclipse of the Sun

1 Draw the Sun, the Moon and the Earth in a line. Write their names.
2 Draw sunlight from the Sun. Let the middle arrow stop at the Moon.
3 Draw the Moon's shadow reaching the Earth. Shade the small patch where it lands.

The Moon's shadow is small. It touches only a narrow strip of the Earth.

People in the strip see the Sun fully covered. The day goes dim. People near the strip see part of the Sun covered. People far away see no change.

An eclipse of the Sun can happen only at new Moon. Then the Moon is between the Earth and the Sun.

The Moon is small, but it is near. The Sun is about 400 times as wide as the Moon. It is also about 400 times as far away. So they look the same size in the sky.

You can watch an eclipse of the Sun safely. Use a pinhole viewer. It makes a small picture of the Sun on paper. You look at the paper, never at the Sun.

Try it

Make a pinhole viewer

You need: a piece of card, about the size of a book, a sheet of paper, a pin, a grown up to help, a sunny day.

Be safe: Never look at the Sun. Not through the hole, not past the card. Look only at the paper. Only a grown up uses the pin.

A grown up pushes a pin through the middle of the card. The hole must be small and round.
Put the paper on the ground in the sunlight.
Stand with your back to the Sun. Never turn round to look at it.
Hold the card up over your shoulder, in the sunlight.
Let the card's shadow fall on the paper. Find the bright spot in it.
Move the card higher or lower. Stop when a small round picture shows.

What you will see: A small round picture of the Sun shows on the paper. Hold the card higher and the picture grows bigger and dimmer. In an eclipse, the picture shows a bite out of the circle.

If you cannot try it, this is what happens.

Small gaps between leaves work like pinholes. Look at the ground under a tree. The bright round spots are pictures of the Sun. In an eclipse they show the bite.

Sometimes the Earth is between the Sun and the Moon. The Earth's shadow falls on the Moon. This is an eclipse of the Moon. Its other name is a lunar eclipse.

The Earth's shadow falls on the Moon.

An eclipse of the Moon can happen only at full Moon. Then the Earth is between the Sun and the Moon.

Sun, Moon and Earth can line up at new or full Moon.

On the dashed line, an eclipse can happen. Not to scale.

Anyone on the night side of the Earth can see it. The Moon often turns dark red. It is safe to look at an eclipse of the Moon.

See it three ways

As a picture

In words

In an eclipse of the Sun, the Moon is in the middle. In an eclipse of the Moon, the Earth is in the middle.

Why is there no eclipse every month? The path of the Moon is tilted a little.

The tilt is drawn much bigger than it is. Most months the Moon is above or below the line. Its shadow misses the Earth.

A wrong idea many people have

There is an eclipse at every new Moon and every full Moon.

Why it feels right: The Moon passes between the Sun and the Earth every month. It seems it must block the Sun.

The test that breaks it: Do this in a dark room. Use a torch for the Sun and a ball for the Earth. Hang a small stone on a thread for the Moon. Swing the stone round the ball in a flat circle. It passes in front of the torch each time. Its shadow falls on the ball. Now tilt the circle a little. The stone misses the line between the torch and the ball. No shadow reaches the ball.

What is true: The Moon's path is tilted a little. Most months it misses the line from the Sun to the Earth. So there is no eclipse.

Key words

eclipse: when one ball is in the shadow of another.
eclipse of the Sun: when the Moon blocks the Sun's light.
eclipse of the Moon: when the Earth's shadow falls on the Moon.
pinhole viewer: a card with a tiny hole. It shows a picture of the Sun on paper.

Back to your guess

The answer is B: The Moon passes in front of the Sun.

The Moon passes between the Sun and the Earth. It blocks the Sun's light. This happens only at new Moon.

Keep it

Copy this into your exercise book.

The Moon blocks the Sun at new Moon. That is an eclipse of the Sun. The Earth's shadow falls on the Moon at full Moon. That is an eclipse of the Moon. Never look at the Sun.

Draw: Draw the Sun, the Moon and the Earth in a line. Draw the Moon's shadow touching the Earth.

Draw the Sun, Earth and Moon

Make a model of the Sun, Earth and Moon

Draw the Sun lighting half of the Earth

Make day and night

Draw a stick and its shadow through the day

Find east and west with a stick

Draw the Earth going round the Sun

Add up the quarter days

Draw the Moon on its orbit

Be the Earth, and let a friend be the Moon

Draw why the Moon changes shape

Make the phases with a ball and a torch

Draw an eclipse of the Sun

Make a pinhole viewer

Key words, A to Z