Chapter 3 of 7

All 7 chapters
  1. 1Sun, Earth and Moon, readunderstood
  2. 2Why we have day and night, readunderstood
  3. 3The Sun seems to move, readunderstood
  4. 4A year: going round the Sun, readunderstood
  5. 5The Moon goes round the Earth, readunderstood
  6. 6Phases of the Moon, readunderstood
  7. 7Eclipses, readunderstood

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

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • 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. A stick stands in the ground. East is on the right, as in the stones map. In the morning the Sun is low on the right, and a long shadow lies to the left, labelled morning. At noon the Sun is high above, and the shadow is a short dark patch at the foot, labelled noon. In the evening the Sun is low on the left, and a long shadow lies to the right, labelled evening. The word shadow is written under the ground.morningshadow

    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. A stick stands in the ground. East is on the right, as in the stones map. In the morning the Sun is low on the right, and a long shadow lies to the left, labelled morning. At noon the Sun is high above, and the shadow is a short dark patch at the foot, labelled noon. In the evening the Sun is low on the left, and a long shadow lies to the right, labelled evening. The word shadow is written under the ground.morningnoonshadow

    2 Draw the Sun high above. Draw a short shadow at the foot. Write noon.

  3. A stick stands in the ground. East is on the right, as in the stones map. In the morning the Sun is low on the right, and a long shadow lies to the left, labelled morning. At noon the Sun is high above, and the shadow is a short dark patch at the foot, labelled noon. In the evening the Sun is low on the left, and a long shadow lies to the right, labelled evening. The word shadow is written under the ground.morningnooneveningshadow

    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.

A flat ground line with a dashed arch over it. The right end of the ground is labelled east and the left end is labelled west. Under the line are the words you face north. The Sun is drawn three times on the arch. On the right, low, it is labelled sunrise. At the top it is labelled midday. On the left, low, it is labelled sunset. A short arrow on the left of the arch points down toward the left, the way the Sun seems to go. Labels: sunrise, midday, sunset, east, west, you face north.sunrisemiddaysunseteastwestyou face north
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.

The Earth seen from above the North Pole, with the Sun on the left, labelled Sun. Three arrows of light go to the Earth, labelled Earth. The half facing the Sun is labelled day. The half facing away is cross hatched and labelled night. A curved arrow beside the Earth shows the way it spins. A white square at the top of the Earth, where day meets night, is labelled sunrise here. A white square at the bottom is labelled sunset here. At the bottom are the words seen from above the North Pole. Labels: Sun, Earth, day, night, sunrise here, sunset here, seen from above the North Pole.SunEarthdaynightsunrise heresunset hereseen from above the North Pole
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

Two rows. In the first row a person, labelled you, has an arrow pointing right, labelled you ride east. In the second row a tree, labelled tree, has an arrow pointing left, labelled seems to go west.youyou ride easttreeseems to go west

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.

The ground seen from above. A dashed line runs from the word west on the left to the word east on the right. A second dashed line runs up and down. A black square in the middle is you. An arrow from you points right, labelled you face east. At the top is the label north, on your left. At the bottom is the label south, on your right. Labels: north, on your left; south, on your right; west; east; you; you face east.north, on your leftsouth, on your rightwesteastyou face eastyou
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.

  1. Push the stick upright into the ground. Check that it does not lean.
  2. Look at its shadow on the ground. Put a stone at the tip of the shadow. Call it stone 1.
  3. Wait about 20 minutes. Do not look at the Sun. The shadow moves.
  4. Put the second stone at the new tip of the shadow. Call it stone 2.
  5. Stand on the line between the stones, in the middle.
  6. 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.
The ground seen from above, with north at the top. A dashed line runs from the word west on the left to the word east on the right. Two stones sit on it, labelled stone 1 and stone 2, with an arrow from stone 1 to stone 2. A stick, labelled stick, stands just below the line on the right. A second dashed line runs up and down through the stick, from the word north at the top to the word south at the bottom. Here the stones lie north of the stick. At another place or time of year they may lie south of it.westeastnorthsouthstone 1stone 2stick

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.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. Which way does the Sun seem to move across the sky?

    Tap your answer.

    1. Yes, that is right. The Earth turns toward the east. So the Sun seems to go west.

    2. Not this one. The Earth turns toward the east. So the Sun seems to go the other way, toward the west. Try another.

    3. Not this one. The Sun seems to go from east to west. It does not go north to south. Try another.

    See the answer

    From east to west

    The Earth turns toward the east. So the Sun seems to go west.

    • If you chose B: The Earth turns toward the east. So the Sun seems to go the other way, toward the west.
    • If you chose C: The Sun seems to go from east to west. It does not go north to south.

  2. Why does the Sun seem to cross the sky?

    Tap your answer.

    1. Not this one. On a bus, the tree seems to move. It is you who move. The Earth turns. Try another.

    2. Yes, that is right. We turn with the Earth. So the Sun seems to move. A tree seems to move from a bus.

    3. Not this one. The Earth is the one that spins. The Sun only seems to move. Try another.

    See the answer

    The Earth turns.

    We turn with the Earth. So the Sun seems to move. A tree seems to move from a bus.

    • If you chose A: On a bus, the tree seems to move. It is you who move. The Earth turns.
    • If you chose C: The Earth is the one that spins. The Sun only seems to move.

  3. Kofi marks the tip of a shadow with a stone. Twenty minutes later he marks it again. Which stone is west?

    Tap your answer.

    1. Not this one. The Sun moves west, so the tip of the shadow moves east. The second stone is east. Try another.

    2. Not this one. They do. The line between the stones runs east and west. Try another.

    3. Yes, that is right. The shadow tip moves east. So the first stone is the western one.

    See the answer

    The first stone

    The shadow tip moves east. So the first stone is the western one.

    • If you chose A: The Sun moves west, so the tip of the shadow moves east. The second stone is east.
    • If you chose B: They do. The line between the stones runs east and west.

  4. You stand between the stones. Stone 1 (west) is on your left. Stone 2 (east) is on your right. Which way do you face?

    Tap your answer.

    1. Yes, that is right. Facing north, west is on your left. East is on your right.

    2. Not this one. If you faced south, west would be on your right. Try another.

    3. Not this one. If you faced east, west would be behind you. Try another.

    See the answer

    North

    Facing north, west is on your left. East is on your right.

    • If you chose B: If you faced south, west would be on your right.
    • If you chose C: If you faced east, west would be behind you.

  5. From an earlier chapter

    Amina holds a ball by a lamp and turns it. Her mark goes from the lit side to the dark side. What does the dark side stand for?

    Tap your answer.

    1. Not this one. The lit side is day. The dark side faces away from the Sun. Go to S2.9.2. Try another.

    2. Yes, that is right. The half that faces away from the lamp is dark. On the Earth, that half has night.

    3. Not this one. The Moon is not in the lamp model. The dark side is the night side. Go to S2.9.2. Try another.

    See the answer

    Night

    The half that faces away from the lamp is dark. On the Earth, that half has night.

    • If you chose A: The lit side is day. The dark side faces away from the Sun. Go to S2.9.2.
    • If you chose C: The Moon is not in the lamp model. The dark side is the night side. Go to S2.9.2.

  6. Draw a stick with its shadow in the morning. Draw it again in the evening. Write which way each shadow points.

    See the answer

    In the morning the shadow is long and points west. In the evening it is long and points east.

    In the morning the Sun is in the east. So the shadow points west. In the evening it is the other way.

  7. Ravi marks the tip of a shadow early, at midday and late. When is the shadow longest?

    Tap your answer.

    1. Not this one. At midday the Sun is high, so the shadow is short. A low Sun makes a long shadow. Try another.

    2. Not this one. A shadow needs light. At night there is no sunlight, so the Sun makes no shadow. Try another.

    3. Not this one. The shadow changes as the Sun climbs and sinks. Watch it through a day. Try another.

    4. Yes, that is right. A low Sun makes a long shadow. At midday the Sun is high, so the shadow is short.

    See the answer

    Early and late in the day, when the Sun is low

    A low Sun makes a long shadow. At midday the Sun is high, so the shadow is short.

    • If you chose A: At midday the Sun is high, so the shadow is short. A low Sun makes a long shadow.
    • If you chose B: A shadow needs light. At night there is no sunlight, so the Sun makes no shadow.
    • If you chose C: The shadow changes as the Sun climbs and sinks. Watch it through a day.

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.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

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