The Earth, Sun and Moon
By the end of this chapter you will be able to
- Describe how the Earth and the other planets move round the Sun, in the solar system
- Describe how the Moon moves round the Earth
- Say that the Sun, Earth and Moon are approximately spherical
- Explain day and night by the Earth turning once in about 24 hours
- Explain why the Sun seems to move across the sky, and why shadows change length through the day
You should already know
- Light and shadows, including how shadows change (Year 3 Science, Chapter 8)
- Materials, and the water cycle (Year 4 Science)
Where this leads
- Gravity, which keeps the planets and the Moon in their orbits (Year 5 Science, Chapter 9)
- Working scientifically, planning and reporting (Year 5 Science, Chapter 1)
National Curriculum for England, Key Stage 2 science, Year 5. Content: E1 describe the movement of the Earth, and other planets, relative to the Sun in the solar system, E2 describe the movement of the Moon relative to the Earth, E3 describe the Sun, Earth and Moon as approximately spherical bodies, E4 use the idea of the Earth's rotation to explain day and night and the apparent movement of the Sun across the sky.
Exercise P Do you remember?
Method. Think about a ball seen from any side.
- Think about the ball. A ball looks like a circle from every side.a circle
- Name the shape. So the shape is a circle.circle
- Write the answer. circle
Check. A ball is a sphere. ✓
Method. Think about what light does when something blocks it.
- Think about the light. When light is blocked by an object, a dark shape forms behind it.dark shape
- Name the shape. The dark shape is called a shadow.shadow
- Write the answer. shadow
Check. Shadows are formed when light is blocked. ✓
Method. Think about the star that gives us daylight.
- Think about daylight. The star that gives us daylight is the Sun.daylight
- Name it. The closest star to the Earth is the Sun.Sun
- Write the answer. Sun
Check. The Sun is a star that is very close to us. ✓
Method. Think about what shines in the night sky.
- Think about the night sky. The Moon is seen in the night sky.night sky
- Name it. The word is Moon.Moon
- Write the answer. Moon
Check. The Moon reflects light from the Sun. ✓
Method. Think about where the Sun is in the morning.
- Think about the Sun. In the morning the Sun is low in the sky, so shadows are longer.low in the sky
- Choose the word. So the longer shadow is the morning one.morning
- Write the answer. morning
Check. At midday the Sun is high, so the shadows are shorter. ✓
The Sun and the planets
The solar system is made of the Sun, and the planets and other objects that move round it. The Sun is a star. It is at the centre of the solar system.
The planets move round the Sun along paths called orbits. The Earth is the third planet from the Sun. There are eight planets in the solar system, in this order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
The Earth takes about 365 days to go once round the Sun. This is one year.
| Planet | Order from the Sun |
|---|---|
| Mercury | 1 |
| Venus | 2 |
| Earth | 3 |
| Mars | 4 |
| Planet | Days to go once round the Sun |
|---|---|
| Mercury | 88 |
| Venus | 225 |
| Earth | 365 |
| Mars | 687 |
Key ideas
- The Sun is at the centre of the solar system.
- The planets move round the Sun along paths called orbits.
- There are eight planets. The Earth is the third planet from the Sun.
- The Earth takes about 365 days to go once round the Sun.
Method. Find the smallest number of days.
- Read the table. Mercury takes 88 days, which is the fewest in the table.88 days
- Name the planet. So the planet is Mercury.Mercury
- Write the answer. Mercury
Check. Mercury is the closest planet to the Sun. ✓
Method. Count the planets from the Sun.
- Count from the Sun. Mercury is first, Venus is second, and the Earth is third.third
- Name the planet. The third planet from the Sun is the Earth.Earth
- Write the answer. Earth
Check. The Earth is the third planet from the Sun. ✓
Method. Subtract the Earth’s days from the Mars days.
- Read the two numbers. Mars takes 687 days, and the Earth takes 365 days.687 and 365
- Subtract. The difference is 687 minus 365, which is 322.687 - 365 = 322
- Write the answer. 322
Check. Check: 365 + 322 = 687. ✓
Watch out. Subtract the smaller number from the larger one.
Watch out
Watch out: the planets do not stay still while they go round the Sun. They are always moving along their orbits.
Try it (with your teacher). Ask your teacher to show a model of the solar system, or a globe with a ball in the middle. Use a torch as the Sun, and a small ball as the Earth. Move the ball slowly round the torch, in a circle, and say which way it moves. Never look straight at the Sun.
Exam tip
Grown-up tip. Ask: “What is in the middle of the solar system? Which planet is the Earth? What does the Earth go round?” Keep the talk factual and calm.
Exercise 8A The Sun and the planets
Method. Read the key ideas in section 8.1.
- Read the key idea. The Sun is at the centre of the solar system.centre
- Name it. So the answer is the Sun.Sun
- Write the answer. Sun
Check. The planets move round the Sun. ✓
Method. Read section 8.1.
- Read the definition. The planets move round the Sun along paths called orbits.paths called orbits
- Name it. The word is orbit.orbit
- Write the answer. orbit
Check. An orbit is the path of a planet round the Sun. ✓
Method. Read the list of planets in section 8.1.
- Read the list. The list has Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.eight names
- Count them. So there are eight planets.8
- Write the answer. 8
Check. Count the names in the list carefully. ✓
Method. Count the planets from the Sun.
- Count. Mercury is first, Venus is second, and the Earth is third.third
- Name it. So the third planet is the Earth.Earth
- Write the answer. Earth
Check. The Earth is the third planet from the Sun. ✓
Method. Read the order of the planets.
- Read the order. Mercury is first in the order from the Sun.first
- Name it. So Mercury is the closest planet to the Sun.Mercury
- Write the answer. Mercury
Check. Mercury is the first planet from the Sun. ✓
Method. Read the order table.
- Read the table. The second row in the order table is Venus.Venus
- Name it. So Venus is second from the Sun.Venus
- Write the answer. Venus
Check. The order table lists the first four planets. ✓
| Planet | Days to go once round the Sun |
|---|---|
| Mercury | 88 |
| Venus | 225 |
| Earth | 365 |
| Mars | 687 |
Method. Read the row for the Earth.
- Read the row. The Earth row shows 365 days.365
- Write the number. So the Earth takes 365 days.365
- Write the answer. 365
Check. This is about one year. ✓
| Planet | Days to go once round the Sun |
|---|---|
| Mercury | 88 |
| Venus | 225 |
| Earth | 365 |
| Mars | 687 |
Method. Find the row with 687.
- Find the row. The row with 687 days is Mars.687
- Name the planet. So the planet is Mars.Mars
- Write the answer. Mars
Check. Mars takes longer than the Earth to orbit the Sun. ✓
| Planet | Days to go once round the Sun |
|---|---|
| Mercury | 88 |
| Venus | 225 |
| Earth | 365 |
| Mars | 687 |
Method. Subtract the Mercury days from the Venus days.
- Read the two numbers. Venus takes 225 days, and Mercury takes 88 days.225 and 88
- Subtract. The difference is 225 minus 88, which is 137.225 - 88 = 137
- Write the answer. 137
Check. Check: 88 + 137 = 225. ✓
Method. Think about the Sun and the planets.
- Think about the Sun. The Sun pulls on the planets.pulls
- Write the reason. So the planets keep moving along orbits round the Sun.orbits round the Sun
- Write the answer. Accept any sentence that says the planets are pulled by the Sun, so they keep moving in orbits round it.
Check. Gravity from the Sun keeps the planets in orbit. ✓
Method. Look for planets after the Earth in the order.
- Find the order. Planets after the Earth are further from the Sun.after the Earth
- Name one. Mars is the next planet after the Earth.Mars
- Write the answer. Accept any one of: Mars, Jupiter, Saturn, Uranus, Neptune.
Check. Any planet after the Earth in the order is further from the Sun. ✓
Method. Think about what a year is.
- Think about the orbit. The Earth takes about 365 days to go once round the Sun.365 days
- Write the reason. That time is one year, so a year is the time of one orbit.one orbit
- Write the answer. Accept any sentence that says the Earth takes about 365 days to go once round the Sun, which is one year.
Check. A year is one orbit of the Earth round the Sun. ✓
The Moon moves round the Earth
The Moon is a natural object that moves round the Earth. Its path round the Earth is its orbit. The Moon takes about a month to go once round the Earth.
The Moon does not make its own light. It reflects light from the Sun, which is why we can see it at night.
The Earth and the Moon both move. The Earth goes round the Sun, and the Moon goes round the Earth at the same time.
Key ideas
- The Moon moves round the Earth, along an orbit.
- The Moon takes about a month to go once round the Earth.
- The Moon does not make its own light, but reflects light from the Sun.
- The Moon’s shape seen from the Earth changes over the month (taught as an example only).
Method. Read section 8.2.
- Read the description. The Moon moves round the Earth.round the Earth
- Name it. So the Moon goes round the Earth.Earth
- Write the answer. Earth
Check. The Earth is the object the Moon goes round. ✓
Method. Read the description.
- Read the description. The Moon takes about a month to go once round the Earth.about a month
- Name the time. So the time is about a month.about a month
- Write the answer. about a month
Check. A month is roughly four weeks. ✓
Method. Read the key ideas.
- Read the key idea. The Moon reflects light from the Sun, so it does not make its own light.reflects light
- Decide. So the answer is no.no
- Write the answer. no
Check. The Moon shines because it reflects sunlight. ✓
Watch out
Watch out: the Moon does not give out its own light. When we see the Moon, we see sunlight that has bounced off its surface.
Try it (with your teacher). With your teacher, use a torch as the Sun and a small ball as the Moon. Hold a larger ball as the Earth. Move the small ball round the larger one, and notice which side of the small ball is lit. Never point the torch at anyone’s eyes.
Exam tip
Grown-up tip. Ask: “What does the Moon go round? Does the Moon make its own light?” Let your child explain the Moon using the word reflects.
Exercise 8B The Moon moves round the Earth
Method. Read section 8.2.
- Read the description. The Moon moves round the Earth.round the Earth
- Name it. So the answer is the Earth.Earth
- Write the answer. Earth
Check. The Moon is a natural object that orbits the Earth. ✓
Method. Read section 8.2.
- Read the description. The Moon takes about a month to go once round the Earth.about a month
- Name the time. So the time is about a month.about a month
- Write the answer. about a month
Check. The Moon’s orbit takes roughly four weeks. ✓
Method. Read the key ideas.
- Read the key idea. The Moon reflects light from the Sun.reflects light
- Decide. So the answer is no.no
- Write the answer. no
Check. We see the Moon because sunlight bounces off it. ✓
Method. Read the key ideas.
- Read the key idea. The Moon reflects light from the Sun.reflects
- Fill the gap. So the missing word is reflects.reflects
- Write the answer. reflects
Check. Reflecting means bouncing light off a surface. ✓
Method. Think about what the Moon orbits.
- Think about the orbit. The Moon goes round the Earth, so the Earth is the larger object.the larger
- Name it. So the larger object is the Earth.Earth
- Write the answer. Earth
Check. The Moon is a smaller object than the Earth. ✓
Method. Read section 8.2.
- Read the description. The Moon goes round the Earth.round the Earth
- Decide. So the statement is false.false
- Write the answer. false
Check. The Earth goes round the Sun, and the Moon goes round the Earth. ✓
Method. Read the labels.
- Read the labels. The label in the middle of the picture says Earth.Earth
- Name it. So the middle object is the Earth.Earth
- Write the answer. Earth
Check. The Moon moves round the Earth in the picture. ✓
Method. Read the list of planets in section 8.1.
- Read the list. The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.not in the list
- Decide. The Moon is not in the list of planets, so the answer is no.no
- Write the answer. no
Check. The Moon moves round the Earth, which is a planet. ✓
Method. Think about one orbit.
- Think about one orbit. One orbit takes about a month.one month
- Make the prediction. Two orbits take about two months.two months
- Write the answer. about two months
Check. Accept any answer close to two months. ✓
Method. Think about where the light comes from.
- Think about the light. The Moon does not make its own light.not its own light
- Write the reason. We see sunlight that has been reflected from the Moon.reflected from the Moon
- Write the answer. Accept any sentence that says the Moon reflects light from the Sun, and we see that reflected light.
Check. The Moon reflects light from the Sun. ✓
Method. Think about the size of the orbit.
- Think about the orbit. The Moon moves along a long path round the Earth.long path
- Write the reason. So one orbit takes about a month, far longer than a day.about a month
- Write the answer. Accept any sentence that says the Moon is much further from the Earth than the Earth turns, and its orbit takes about a month.
Check. A day is the time for the Earth to turn once. ✓
The Sun, Earth and Moon are spheres
A sphere is a ball-shaped object. It looks like a circle from every direction. The Sun, the Earth and the Moon are approximately spherical: they are nearly round balls, with very slightly flattened shapes.
Round objects in space pull each other into rounded shapes, so the bodies in space tend to be spherical.
Key ideas
- A sphere looks like a circle from every direction.
- The Sun, the Earth and the Moon are approximately spherical.
- The word approximately means nearly, not exactly.
- A flat card circle is not a sphere, but a ball made from it would be.
Method. Read the key ideas in section 8.3.
- Read the key idea. The Earth is approximately spherical.approximately spherical
- Name the shape. So the shape is a sphere.sphere
- Write the answer. sphere
Check. A sphere looks like a circle from every side. ✓
Method. Read the key ideas.
- Read the key idea. The Sun, the Earth and the Moon are approximately spherical.the Moon
- Decide. So the answer is yes.yes
- Write the answer. yes
Check. The Moon is nearly a round ball. ✓
Method. Think about a ball.
- Think about the ball. A ball looks like a circle from every side.every side
- Name the answer. So a sphere looks like a circle from every direction.every direction
- Write the answer. every direction
Check. The circle is the same from any side. ✓
Watch out
Watch out: approximately spherical does not mean perfectly round. The Earth is slightly flattened at the top and bottom, but it is still very nearly a ball.
Try it (with your teacher). Use a ball of modelling clay, and a flat circle cut from card. Turn the ball and the circle in your hands. Which one looks like a circle from every side? Write one sentence about your answer.
Exam tip
Grown-up tip. Ask: “Which shape looks the same from every side? Which shape is a ball?” Let your child explain the word approximately.
Exercise 8C The Sun, Earth and Moon are spheres
Method. Read section 8.3.
- Read the description. A sphere is a ball-shaped object.ball-shaped
- Name it. The word is sphere.sphere
- Write the answer. sphere
Check. A sphere looks like a circle from every direction. ✓
Method. Read the key ideas.
- Read the key idea. The Sun, the Earth and the Moon are approximately spherical.the Sun
- Decide. So the answer is yes.yes
- Write the answer. yes
Check. The Sun is nearly a round ball. ✓
Method. Read the watch-out box in section 8.3.
- Read the watch-out. Approximately spherical does not mean perfectly round.not perfectly round
- Decide. So the Earth is approximately, not exactly, spherical.no
- Write the answer. no
Check. The Earth is nearly a ball, but very slightly flattened. ✓
Method. Read the key ideas.
- Read the key idea. The word approximately means nearly, not exactly.nearly
- Name the word. So the word is nearly.nearly
- Write the answer. nearly
Check. Accept nearly or roughly. ✓
Method. Read section 8.3.
- Read the description. A sphere looks like a circle from every direction.every direction
- Name the answer. So the answer is every direction.every direction
- Write the answer. every direction
Check. The outline is the same from any side. ✓
Method. Count the circles in the picture.
- Count the circles. The picture shows three circles: the Sun, the Earth and the Moon.three circles
- Write the number. So three objects are shown as circles.3
- Write the answer. 3
Check. Each circle stands for a nearly spherical body. ✓
Method. Read the labels in the picture.
- Read the labels. The middle circle is labelled Earth.middle
- Name it. So the labelled object is the Earth.Earth
- Write the answer. Earth
Check. The Earth is shown in the middle, and is nearly a ball. ✓
Method. Think about the shape of a card circle.
- Think about the card. A card circle is flat, and only looks like a circle from one side.flat
- Decide. So the statement is false.false
- Write the answer. false
Check. A ball made from the card would be a sphere. ✓
Method. Think about what both shapes look like.
- Think about both. Both a sphere and a flat circle look like a circle from one side.one side
- Write the word. So the shared word is circle, or round.circle
- Write the answer. Accept circle, or round.
Check. Both look round from one direction. ✓
Method. Think about the shape of a ball.
- Think about the ball. A ball is the same distance from its centre in every direction.same distance
- Write the reason. So its outline is a circle from every side.circle from every side
- Write the answer. Accept any sentence that says a ball is round in every direction, so its outline is a circle from every side.
Check. A sphere is round in every direction. ✓
Method. Think about the word approximately.
- Think about the shape. The Sun, Earth and Moon are nearly round balls.nearly round
- Write the reason. They are slightly flattened, so the word approximately is used.slightly flattened
- Write the answer. Accept any sentence that says the bodies are nearly round balls, but very slightly flattened, so approximately is the right word.
Check. Approximately means nearly, not exactly. ✓
Day and night, and the Earth turning
The Earth rotates. This means it turns round on its own axis, like a spinning top. It takes about 24 hours to turn once.
The side of the Earth that faces the Sun has day. The other side is in night. As the Earth turns, places move from night into day, and back again.
The Sun seems to move across the sky, from east to west, because the Earth is turning. This movement is called the apparent movement of the Sun: it appears to move, but the Sun is not really moving across the sky.
Key ideas
- The Earth turns on its own axis, once in about 24 hours.
- The side facing the Sun has day, and the other side has night.
- The Sun seems to move across the sky because the Earth is turning.
- Shadows change length during the day, because the Sun appears to move.
Method. Read the key idea in section 8.4.
- Read the key idea. The Earth takes about 24 hours to turn once.24 hours
- Write the number. So the answer is 24 hours.24
- Write the answer. 24
Check. Day and night together make one full turn of 24 hours. ✓
Method. Read the picture.
- Read the picture. The side of the Earth facing the Sun is lit, and has day.facing the Sun
- Name the part. So the part with day is the side facing the Sun.facing the Sun
- Write the answer. the side facing the Sun
Check. The other side has night. ✓
Method. Think about the Earth.
- Think about the Earth. The Earth is turning, so the Sun seems to move across the sky.Earth is turning
- Choose the word. So the word is turning.turning
- Write the answer. turning
Check. The Sun is not really moving across the sky; the Earth is turning. ✓
Watch out
Watch out: the Sun does not go round the Earth each day. It is the Earth that turns, so the Sun only appears to move.
Try it (with your teacher). Ask your teacher to set up a torch as the Sun and a globe as the Earth, in a dark room. Mark a place on the globe with a sticker, and turn the globe slowly, anticlockwise, while the torch shines. Watch the sticker move from light to dark. Never point the torch at anyone’s eyes.
Exam tip
Grown-up tip. Ask: “Does the Sun move, or does the Earth turn? Where does the Sun come up in the morning?” Let your child explain using the word turn.
Exercise 8D Day and night, and the Earth turning
Method. Read the key idea in section 8.4.
- Read the key idea. The Earth takes about 24 hours to turn once.24 hours
- Write the number. So the answer is 24.24
- Write the answer. 24
Check. The turn gives one day and one night. ✓
Method. Read the key idea in section 8.4.
- Read the description. The Earth rotates, which means it turns round on its own axis.rotates
- Name it. The word is rotation.rotation
- Write the answer. rotation
Check. Rotation makes day and night. ✓
Method. Read the picture in section 8.4.
- Read the picture. The side facing the Sun is lit.lit
- Name the part. So the part in day is the side facing the Sun.facing the Sun
- Write the answer. the side facing the Sun
Check. The side away from the Sun is in night. ✓
Method. Read section 8.4.
- Read the description. The Sun seems to move because the Earth is turning.Earth is turning
- Fill the gap. So the missing word is turning.turning
- Write the answer. turning
Check. The Sun is not really moving across the sky. ✓
Method. Read the watch-out box in section 8.4.
- Read the watch-out. It is the Earth that turns, so the Sun only appears to move.the Earth that turns
- Decide. So the answer is no.no
- Write the answer. no
Check. The Earth rotates, so the Sun appears to move. ✓
Method. Read section 8.4.
- Read the description. The Sun seems to move across the sky from east to west.east to west
- Name the direction. So the direction is east to west.east to west
- Write the answer. east to west
Check. The Sun rises in the east and sets in the west. ✓
Method. Read the labels in the picture.
- Read the labels. The night label is on the side away from the Sun.night label
- Name the side. So the side with night is the side away from the Sun.away from the Sun
- Write the answer. the side away from the Sun
Check. The side facing the Sun is in day. ✓
Method. Read the labels in the picture.
- Read the picture. The midday shadow is the shortest of the three.shortest
- Choose the word. So the midday shadow is short.short
- Write the answer. short
Check. The Sun is highest at midday, so the shadow is shortest. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the shortest shadow in the table.
- Find the shortest. The shortest shadow is 12 cm, at midday.12 cm
- Name the time. So the shadow was shortest at 12 o’clock, midday.midday
- Write the answer. 12 o’clock, midday
Check. At midday the Sun is at its highest. ✓
Method. Think about a fair test.
- Think about the test. Only the time of day should change in the test.time of day
- Write one thing. The stick, the place and the ground must stay the same.stay the same
- Write the answer. Accept any one of: the same stick, the same place, the same type of ground.
Check. A fair test changes one thing only. ✓
Method. Think about the turning Earth.
- Think about the Earth. The Earth turns on its own axis.turns
- Write the reason. So each side of the Earth faces the Sun in turn, giving day and night.in turn
- Write the answer. Accept any sentence that says the Earth turns once in about 24 hours, so each place faces the Sun in turn.
Check. Day and night come from the turning of the Earth. ✓
Method. Think about the turning Earth.
- Think about the turning. The Earth turns, so places move into the Sun’s light.turns
- Write the reason. So the Sun appears to rise in the east, and set in the west.rise in the east
- Write the answer. Accept any sentence that says the Earth turns from west to east, so the Sun appears to rise in the east.
Check. The Sun appears to move across the sky as the Earth turns. ✓
Models, shadows and evidence
Scientists use models to help explain things that are too large, too far away, or too slow to see. A model of the Earth and the Sun can help us to explain day and night, but we must remember that the model is not the real thing.
A fair test with a stick and the Sun can show how the shadow changes through the day. The table records the shadow length at four times of day.
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Key ideas
- A model helps us to explain things we cannot see directly, but it is not the real thing.
- Shadows are shortest at midday, when the Sun is highest.
- Shadows are longer in the morning and the afternoon.
- Shadows change length because the Sun appears to move across the sky.
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the longest shadow.
- Read the lengths. The longest shadow is 60 cm, at 8 o’clock in the morning.60 cm
- Name the time. So the longest shadow was at 8 o’clock in the morning.8 o’clock in the morning
- Write the answer. 8 o’clock in the morning
Check. The Sun is low in the morning. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Subtract the shorter shadow from the longer one.
- Read the two lengths. The morning shadow is 60 cm, and the midday shadow is 12 cm.60 and 12
- Subtract. The difference is 60 minus 12, which is 48.60 - 12 = 48
- Write the answer. 48
Check. Check: 12 + 48 = 60. ✓
Method. Think about the model.
- Think about the model. The lit side of the model is day, and the dark side is night.lit side
- Decide. So the model shows day and night, and the answer is yes.yes
- Write the answer. yes
Check. A model can help, but it is not the real Earth. ✓
Watch out
Watch out: a model is a simplified picture of the real thing. A torch is not really the Sun, and a ball is not really the Earth. Use the model to think, then check with evidence.
Try it (with your teacher). With your teacher, stand a stick in the ground, or a pencil in a lump of clay, in a sunny place outside. Mark the end of the shadow with a stone at the same time each hour, for three or four hours. Use a measuring tape to find the length of each shadow. Record your results in a table. Never look directly at the Sun.
Exam tip
Grown-up tip. Ask: “What happens to the shadow as the day goes on? Why?” Let your child compare the model and the real shadow.
Exercise 8E Models, shadows and evidence
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Read the row for 2 o’clock.
- Read the row. The 2 o’clock row shows 28 cm.28 cm
- Write the number. So the shadow at 2 o’clock was 28 cm.28
- Write the answer. 28
Check. The shadow at 2 o’clock is shorter than in the morning. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the shortest shadow.
- Find the shortest. The shortest shadow is 12 cm.12 cm
- Name the time. That shadow is at 12 o’clock, midday.midday
- Write the answer. 12 o’clock, midday
Check. At midday the Sun is highest. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Add the four lengths.
- Add the lengths. The four lengths are 60, 30, 12 and 28 cm.60 + 30 + 12 + 28
- Find the total. The total is 130 cm.130
- Write the answer. 130
Check. Check: 60 + 30 = 90, then 12 + 28 = 40, and 90 + 40 = 130. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the row with 30 cm.
- Find the row. The row with 30 cm is for 10 o’clock.30 cm
- Name the time. So the time is 10 o’clock.10 o’clock
- Write the answer. 10 o’clock
Check. The shadow shrinks as the Sun rises higher. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Read the table in order of time.
- Read the table. The shadow goes from 60 cm to 30 cm to 12 cm.gets smaller
- Choose the word. So the shadows are getting shorter.shorter
- Write the answer. shorter
Check. The Sun gets higher, so the shadows get shorter. ✓
Method. Read the watch-out box in section 8.5.
- Read the watch-out. A model is a simplified picture, and a torch is not really the Sun.not really the Sun
- Decide. So the answer is no.no
- Write the answer. no
Check. A model helps us think, but it is not the real thing. ✓
Method. Read the key ideas in section 8.5.
- Read the key idea. Shadows are shortest at midday, when the Sun is highest.shortest
- Name the time. So the shadow is shortest at midday.midday
- Write the answer. midday
Check. The Sun is highest at midday. ✓
Method. Think about the Sun in the afternoon.
- Think about the Sun. In the afternoon the Sun is lower again, so shadows get longer.lower
- Make the prediction. So the shadow at 4 o’clock should be longer than at midday.longer
- Write the answer. yes
Check. Check the prediction with the shadow test, with your teacher. ✓
Method. Think about the height of the Sun.
- Think about the Sun. At midday the Sun is at its highest in the sky.highest
- Write the reason. So the shadow is shorter at midday than in the morning.shorter
- Write the answer. Accept any sentence that says the Sun is higher in the sky at midday, so the shadow is shorter.
Check. A higher Sun casts a shorter shadow. ✓
Method. Think about models and evidence.
- Think about the model. A model of the Earth and a torch helps us see how day and night happen.helps us see
- Think about the check. The model is simplified, so we check it with evidence such as shadows.check it
- Write the answer. Accept any two sentences that say a model helps us to think about the Earth turning and the Sun, but the model is simplified, so we must check it against evidence.
Check. A model is useful, but evidence decides. ✓
Chapter summary
| Skill | Method |
|---|---|
| The solar system | The Sun is at the centre. Eight planets move round it along orbits. The Earth is the third planet. |
| The Moon | The Moon moves round the Earth, taking about a month. It reflects light from the Sun. |
| Spheres | The Sun, the Earth and the Moon are approximately spherical: nearly round balls. |
| Day and night | The Earth rotates once in about 24 hours. The side facing the Sun has day, and the other side has night. |
| The Sun in the sky | The Sun appears to move from east to west, because the Earth turns. |
| Shadows | Shadows are shortest at midday, when the Sun is highest, and longer in the morning and afternoon. |
Can you…?
- I can describe how the Earth and other planets move round the Sun, in the solar system
- I can describe how the Moon moves round the Earth, and say it reflects light
- I can say the Sun, the Earth and the Moon are approximately spherical
- I can explain day and night using the Earth turning once in about 24 hours
- I can explain why the Sun appears to move across the sky, and why shadows change length
Key terms
- solar system
- the Sun, and the planets and other objects that move round it
- orbit
- the path along which a planet or moon moves round another object
- rotation
- turning round on its own axis, as the Earth does once in about 24 hours
- sphere
- a ball-shaped object, which looks like a circle from every direction
- approximately
- nearly, but not exactly
- reflect
- to bounce light off a surface, as the Moon reflects light from the Sun
- apparent movement
- a movement that seems to happen, such as the Sun moving across the sky, but is caused by something else
- model
- a simplified picture or object that helps us to explain something we cannot see directly
Exercise 8Z Check-up
Method. Read section 8.1.
- Read the key idea. The Sun is at the centre of the solar system.centre
- Name it. So the answer is the Sun.Sun
- Write the answer. Sun
Check. The planets move round the Sun. ✓
Method. Count the planets from the Sun.
- Count. Mercury is first, Venus is second, and the Earth is third.third
- Name it. So the third planet is the Earth.Earth
- Write the answer. Earth
Check. The Earth is the third planet from the Sun. ✓
Method. Read section 8.2.
- Read the description. The Moon goes round the Earth.round the Earth
- Name it. So the answer is the Earth.Earth
- Write the answer. Earth
Check. The Moon takes about a month to go round. ✓
Method. Read section 8.2.
- Read the key idea. The Moon reflects light from the Sun.reflects light
- Decide. So the answer is no.no
- Write the answer. no
Check. We see the Moon because the sunlight bounces off it. ✓
Method. Read section 8.3.
- Read the key idea. The Sun, the Earth and the Moon are approximately spherical.approximately spherical
- Decide. So the answer is yes.yes
- Write the answer. yes
Check. They are nearly round balls. ✓
Method. Read the key idea in section 8.4.
- Read the key idea. The Earth takes about 24 hours to turn once.24 hours
- Write the number. So the answer is 24.24
- Write the answer. 24
Check. Day and night make one full turn of 24 hours. ✓
Method. Read section 8.4.
- Read the description. The Sun seems to move because the Earth is turning.turning
- Fill the gap. So the missing word is turning.turning
- Write the answer. turning
Check. The Sun is not really moving across the sky. ✓
| Planet | Days to go once round the Sun |
|---|---|
| Mercury | 88 |
| Venus | 225 |
| Earth | 365 |
| Mars | 687 |
Method. Read the row for the Earth.
- Read the row. The Earth row shows 365 days.365
- Write the number. So the Earth takes 365 days.365
- Write the answer. 365
Check. This is about one year. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the shortest shadow.
- Find the shortest. The shortest shadow is 12 cm.12 cm
- Name the time. So the time is 12 o’clock, midday.midday
- Write the answer. 12 o’clock, midday
Check. At midday the Sun is highest. ✓
Method. Think about the turning Earth.
- Think about the Earth. The Earth turns on its own axis.turns
- Write the reason. So each side faces the Sun in turn, giving day and night.in turn
- Write the answer. Accept any sentence that says the Earth turns once in about 24 hours, so each side faces the Sun in turn.
Check. Day and night come from the turning of the Earth. ✓
Total 16 marks. Allow about 16 minutes.
Exercise 8X Practice test questions
Method. Read the order of the planets.
- Read the order. Mercury is the first planet from the Sun.first
- Name it. So the closest planet is Mercury.Mercury
- Write the answer. Mercury
Check. Mercury is the first planet from the Sun. ✓
Method. Read section 8.1.
- Read the definition. The planets move round the Sun along paths called orbits.paths called orbits
- Name it. The word is orbit.orbit
- Write the answer. orbit
Check. An orbit is a path round the Sun. ✓
Method. Read section 8.2.
- Read the description. The Moon moves round the Earth.round the Earth
- Name it. So the answer is the Earth.Earth
- Write the answer. Earth
Check. The Earth is the planet the Moon orbits. ✓
Method. Read section 8.3.
- Read the key idea. The Sun, the Earth and the Moon are approximately spherical.approximately spherical
- Decide. So the answer is yes.yes
- Write the answer. yes
Check. They are nearly round balls. ✓
Method. Read section 8.4.
- Read the key idea. The Earth takes about 24 hours to turn once.24 hours
- Write the number. So the answer is 24.24
- Write the answer. 24
Check. Day and night come from one turn of 24 hours. ✓
| Planet | Days to go once round the Sun |
|---|---|
| Mercury | 88 |
| Venus | 225 |
| Earth | 365 |
| Mars | 687 |
Method. Subtract the Earth’s days from the Mars days.
- Read the numbers. Mars takes 687 days, and the Earth takes 365 days.687 and 365
- Subtract. The difference is 687 minus 365, which is 322.687 - 365 = 322
- Write the answer. 322
Check. Check: 365 + 322 = 687. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Subtract the shortest shadow from the longest.
- Read the lengths. The longest is 60 cm, and the shortest is 12 cm.60 and 12
- Subtract. The difference is 60 minus 12, which is 48.60 - 12 = 48
- Write the answer. 48
Check. Check: 12 + 48 = 60. ✓
Method. Think about the turning Earth.
- Think about the Earth. The Earth turns on its own axis.turns
- Write the reason. So the Sun seems to move across the sky, even though it is the Earth that moves.seems to move
- Write the answer. Accept any sentence that says the Earth turns, so the Sun seems to move across the sky, although the Sun is not really moving.
Check. The apparent movement comes from the turning Earth. ✓
Method. Think about the Moon and the light.
- Think about the orbit. The Moon takes about a month to go once round the Earth.about a month
- Think about the light. The Moon reflects light from the Sun, so we can see it at night.reflects light
- Write the answer. Accept any two sentences that say the Moon orbits the Earth in about a month, and it reflects light from the Sun, so we can see it at night.
Check. The Moon moves round the Earth and reflects sunlight. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Think about the height of the Sun.
- Think about the Sun. At midday the Sun is at its highest in the sky.highest
- Write the reason. So the shadow is shorter at midday.shorter
- Write the answer. Accept any sentence that says the Sun is higher in the sky at midday, so the shadow is shorter.
Check. A higher Sun makes a shorter shadow. ✓