The solar system

  • How can we tell the difference between a star and a planet?
  • What are asteroids?
  • What is a moon? Does the Moon produce its own light?
  • Can we see the Moon during the day?

Do you remember that in Gr. 4 we looked at Space and the objects found in Space? Last year, in Gr. 5 we mostly looked at Earth and the features of Earth. Now we are going to explore Space a bit more! Before carrying on, let's refresh our memories on some of the things about Space from Gr. 4.

Wordsearch about Space.


  1. Find the following words in the wordsearch.
  2. Draw a circle around each word.
  3. When you find the word, discuss with your partner what you remember about this word from Gr. 4.
  • space
  • gravity
  • astronomy
  • orbit
  • rotate
  • moon
  • axis
  • galaxy
  • sunrise
  • sunset
  • star

Teacher guide answer:

The Sun, planets and asteroids

Do you remember what a solar system is? Our solar system is made up of the Sun and the planets. Let's take a look!

What is the Sun?

The Sun glows so fiercely that it is not safe to look straight at it, even though it is so far away. The Sun is a ball of gases.

The temperature at the centre of the Sun is about 15 000 000 degrees Celsius! The surface is about 5 500 degrees Celsius. That is extremely hot! Can you see the explosion from the surface of the Sun in the picture?!

Can you see the big burst of gas from the Sun in the bottom left?

The Sun is a star, because it produces its own energy. The Sun appears bigger and brighter because it is much nearer to Earth than the other stars.

The Sun is about 420 times bigger than the Earth and about 1700 times bigger than the Moon! The Sun is much further away than the Moon from the Earth. The Sun produces light and heat. The heat warms the surface of the Earth.

Study the image of the Sun, and then answer the questions that follow in the activity below.

This image shows the different layers of the Sun.

The core of the Sun


  1. Look at the picture of the Sun showing the different layers inside.
  2. Answer the questions.


Which is the hottest part of the Sun?

The hottest part of the Sun is the core, that is, the middle, white part.

The Sun's energy comes from gases being squeezed together until hydrogen turns into helium. Where do you think the gases are squeezed together the hardest?

in the core

What are the dark spots on the surface of the Sun called?


Come with me! We are going to hear a story about the planets. It's a bit of science, maths and history all mixed up!


The following pages contain a lot of text and not much in the way of activities and writing. This is intended to be told as an interesting story to your learners. Read through this together. Get learners to read different parts at different times. As you are going through it, ask the class different questions, such as "Do you know the names of any constellations?", "Can you remember the names of all 8 planets?", "Do you know the names of any other Greek philosophers?" (E.g. Socrates, Plato, Aristotle). This can also be used as revision to remind learners about what they learnt in Gr. 4 about the solar system.

Long, long ago, people watched the stars at night. Shepherds looking after sheep and cattle would lie down and look at the night sky. People in hot regions like Mesopotamia (now Iraq) slept on the roofs of their houses. They had plenty of time to look at the stars. They knew the patterns of stars in the sky and how the stars moved across the sky during the night. The patterns were fixed (they did not change). For example, you can find a pattern like the Southern Cross if you look up towards the South. You can see it in the first photo below. The second photo with white lines helps you to see the Cross. It always looks the same because the stars are always the same distance apart.

This pattern of stars is the Southern Cross. The pattern does not change.
The white lines are not really in the sky, they just show you how to view the Southern Cross.

Patterns of stars are called constellations. The next image shows some other famous constellations of stars which you can see in the night sky.

Some constellations of stars making up patterns in the sky

People noticed that some bright objects did not behave like the others. These objects are close to a star one night and then the next night, at the same time, the object has moved away from the star. Night after night, these objects appear in new positions among the stars.

The Greeks of those times called these objects "the wanderers" because they were in a slightly different position each night. The Greek word for wanderer is "planetes" and so we get the English word "planet". A person who wanders is someone who walks around wherever he feels like going.

The planets were a science puzzle

People who study the stars are called astronomers. The planets were a puzzle for ancient astronomers. Why did they move differently to the stars? Were they just as far away as the stars? Why were they brighter at some times of the year than at other times?

You can see the planet Venus just after the Sun has set. Venus is usually very bright. At some times of the year, you have to look for Venus in the dark sky where the Sun will rise.

The ancient peoples gave names to the planets. For example, Mars was named after the god of war. One planet was so beautiful that they called it Venus after the goddess of love and beauty.

You can see Mars at some times of the year. Mars is orange-red, and at most times it looks smaller than Venus. It is not as easy to find as Venus is; sometimes you have to look late at night to see Mars rising in the east.

How astronomers solved the puzzle

Over hundreds of years, astronomers set up observatories in places like India, Egypt, Iraq, England and countries in Europe. An observatory is a building that has permanent measuring marks. These marks are always in the same position. The astronomers make notes of where stars and planets are compared to these fixed positions, and they note the dates and times.

Hypatia was an astronomer and mathematician at the University of Alexandria in Egypt. She lived about 1700 years ago. Can you see the globe next to her in this old drawing?

Over many years of careful observing, the astronomers kept records of where the planets moved. They used maths to predict where a planet would be on a future date. Then, on that date, they went to check if their prediction was correct. They became very good at measuring, doing maths and doing calculations with big numbers.

Ancient astronomers making observations

So they worked out that the planets are closer to us than the stars, and that the planets are moving around the Sun. Then they realised that Earth is a planet too, and it is moving around the Sun!

This idea upset some people who believed that the Earth was the centre of the universe and that everything moved around the Earth. Nowadays we know exactly where each planet in our solar system is at any time, and we can actually send spacecraft to the planets.

The Sun together with the planets moving around it is called the solar system. You will learn about that next.

The solar system

The solar system consists of the Sun and all the planets that orbit around it. It also includes asteroids and the planets' moons.

In the first image, you can see a diagram of the solar system. In the second image in the next activity, you can see another diagram of the solar system. Both these diagrams try to show you what the solar system is like.

The solar system consisting of the Sun and 8 planets

In the solar system, each object's force of gravity pulls on all the other objects. Gravity is a force of attraction between objects. The Sun is the biggest and heaviest object in our solar system and so it exerts the greatest force of gravity on all the planets. This force of gravity makes all the planets move in circles around the Sun.

The names of the planets in our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury is the planet closest to the Sun and Neptune is the planet furthest from the Sun.

Earth is the third-closest planet to the Sun. Find Earth in the picture.

Could the planets really be as close to the Sun as the picture shows? Give some reasons for your answer.

No, they are not really this close. Reason 1: A person on Earth would see the Sun filling half the sky, but we know that the real Sun looks quite small in the sky. Reason 2: All the water on Earth would have evaporated and all living things would burn up.

Looking at the solar system from far away in Space


  1. Imagine you are in a spacecraft very far from the Earth. You can see the planets all moving around the Sun in orbits, like in the picture. The white lines in the picture show the path that each planet follows when orbiting the Sun. These orbits (white lines) are not actually visible.
  2. Look at the picture and answer the questions.


Which planet is the closest to the Sun?


Is Venus or Earth closer to the Sun?

Venus. The learners can see this if they follow the orbit of Venus and Earth with a pencil. Tell the learners to compare this diagram with the previous one and use the information they have already got above, about the order of the planets. This teaches learners that textbooks provide information in different places because they cannot provide all information in the same place.

Write the names of the planets in order, beginning from the one that is closest to the Sun.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury is the planet closest to the Sun and Neptune is the planet furthest from the Sun.

Which planet do you think is the coldest, and why?

Neptune. It is the furthest away from the Sun.

Why do the planets all keep on moving in orbits around the Sun?

The force of gravity between the Sun and each planet keeps them moving in their orbits. The Sun is so big and heavy that it can exert a force of gravity that pulls even the furthest planet, Neptune, into its orbit.

Let's now use our bodies to create a model of how the planets move around the Sun!

Make a model of two planets moving around the Sun

This is a demonstration, using two learners at a time. One learner must run with the ball to get it moving in a circle. You need plenty of room; at least a clear 10-metre-diameter circle. The long string helps to give learners the correct idea that the Earth's orbit is at a very great radius from the Sun. Plan this to happen at the start or end of a period, because the learners take time to move outside. This activity was also included in the Gr. 4 workbook to show revolution of the planets around the Sun. In Gr. 6, it is also important for learners to understand that not only do planets revolve around the Sun, but they also rotate on their axis. After doing this activity, also get one learner to stand in the centre as the Sun and hold several pieces of string, or you the teacher can do this. Several learners then hold the ends of the strings and spread out and walk around the teacher/learner in the middle. They are now revolving. As they are revolving, ask learners to now also spin as they are revolving. Explain that they are now also rotating as planets rotate on their axis at the same time that they are revolving around the Sun.


  • strong string about 5 metres long
  • another strong string about 3 metres long
  • two balls in plastic bags
  • eight thick rubber bands
  • a small chair or a box like a plastic milk crate


  1. Tie the four elastic bands onto the handles of the plastic bag. Then tie the string onto the four elastic bands. Put one ball inside the bag.
  2. You are going to do as you see in the next picture.
  3. Someone must run with the ball in the bag to help you get it going.
  4. Then swing the ball around as fast as you can, on the end of the string.
  5. The rest of the class must watch the plastic bag carefully to see whether the rubber bands stretch.
  6. You see the learner in the picture swinging the ball around himself. The learner represents the Sun and the ball represents the Earth.
  7. Take turns to swing the ball; feel how hard you need to pull on the ball to keep it going around.
  8. The people who are watching will see the rubber bands stretch. This means that the ball is pulling on the string, and the string is pulling on the ball.


What does the learner who is swinging the ball represent? What does the ball represent?

The learner is the Sun and the ball is the Earth.

What do you feel is happening to the elastic as you swing the ball?

You will feel the string pulling on your hand.

If the ball in its bag could feel, what would it feel?

The ball will feel a force pulling on it equal to what the hand feels.

If the string breaks, in what direction will the ball carry on travelling? Draw an arrow on the picture to show the direction the ball would carry on moving in.

Give learners time to think about this, and commit themselves to an answer. The answer is that the ball will continue travelling in the direction it's going at the moment the string breaks. Learners can test this answer by letting the string go.

The ball represents the Earth. The learner swings it quite fast, but how long does the Earth really need to go once around the Sun?

It takes the Earth one year to orbit the Sun.


  1. This part is more difficult and it needs some practice. You are still making a model of planets moving around the Sun.
  2. Use the 3-metre string and tie it onto a bag and ball as you did before.
  3. In the picture you see one learner standing on a stool and swinging another netball in a bag.
  4. The first learner now has to walk around the stool to keep his ball moving.
  5. This might take some time to get it right!
Two learners must now swing balls at the same time. This is quite tricky!


Which part of this model represents the Sun?

The two learners together represent the Sun.

Which part of the model represents planet Earth?

The first ball on the 5-metre string represents Earth.

Which part represents planet Venus?

The second ball on the 3-metre string represents Venus.

In this model, when Earth revolves around once, how long a period of time does that represent?

It takes one year.

The planet Earth orbits around the Sun in 365.25 days and we call that one year. As Earth moves to new positions around the Sun, we have four seasons: summer, autumn, winter and spring, and then summer comes again.

Now in Space, the Earth keeps on going around the Sun at more than 100 000 kilometres every hour. However, there is no string pulling on the Earth, so what keeps it moving?

The force of gravity pulls the Sun and the Earth towards each other.

There is no string in Space between Earth and the Sun! The Earth would move away, but the Sun "traps" the Earth with its much greater force of gravity. The Sun pulls on the Earth and the Earth pulls on the Sun with the force of gravity. The pull is so strong that it works at a distance of 150 million kilometres! Like the string, force of gravity keeps the Earth moving in its orbit around the Sun, year after year.

It does the same for the other planets too. The force of gravity pulls the planet Neptune into its orbit even though Neptune is 30 times further away from the Sun than Earth is.

In the model in the previous activity, what does the string represent?

The string represents the force of gravity between the Sun and a planet.

We visit the eight planets

The four inner planets are rocky.

Look at the picture below of the solar system again. The 4 planets closest to the Sun are called the inner planets of the solar system. They all are made of rock; some of them have a thin layer of gas on the outside. Earth has a very thin layer of water and soil too.

These are the 4 inner rocky planets. This shows their sizes compared to each other. Can you name them?

The next image shows us what the core of each of the rocky planets looks like. The core is the inner part of the planet and it is made up of different layers.

The core of each of the four inner rocky planets of our solar system.

Give the names of the four inner, rocky planets by looking at the pictures above.

The learners must work it out from the figure. The skill is interpreting the picture below and the text above. Mercury, Venus, Earth, Mars

Name the 3 layers of the rocky planets. Hint: They are each given a different colour in the image above.

crust, mantle, core

The four outer planets are gas giants.

These planets are very far from the Sun. They don't have a hard surface that a spacecraft can land on. Instead, they are giant balls of very cold gases. Astronomers think that these planets have hot, solid cores, deep down inside them.

This diagram shows the different sizes of the planets. Can you see how much bigger the 4 outer gas giants are?!

This next image shows us what the inside of the gas giants is like. There are also different layers of gases.

The four gas giants, showing the gases which make up these planets

Give the names of the four outer, gas planets by looking at the pictures above.

The learners must work it out from the picture. Jupiter, Saturn, Uranus and Neptune

Give the name of one of the gases that make up the gas planets.

The gas planets are made up of hydrogen, helium or methane.

Let's now take a closer look at each of the planets.

Mercury is closest to the Sun, and the smallest planet. It has no atmosphere and its grey surface is marked with thousands of craters. A crater is the mark that we see where a rock has crashed onto a planet or a moon.

Can you see all the craters on the surface of Mercury?!

Venus is second closest to the Sun. It is almost the same size as Earth. To us, it looks white and it shines brightly in the evening or morning.

Venus shines brightly like that because it is covered in a thick cloud of gas. It would be horrible to breathe the atmosphere on Venus, because the gas is mostly carbon dioxide and sulphuric acid! The atmosphere absorbs lots of heat from the Sun and does not cool down at night. Venus is the hottest planet in our solar system.

This beautiful image of Venus was created from a whole lot of photographs taken by NASA over 10 years, put together to make a single image.
Venus rising next to the Moon

At what temperature does water boil?

100 degrees Celsius

Zinc melts at about 420°C, so what would zinc look like on the surface of Venus?

It would be a liquid.

Then we reach Earth - the blue planet, our home in Space. You know a lot about Earth already. Earth has its Moon that we know well. The Moon moves in its orbit around the Earth.

This image is from a satellite tracking a hurricane moving over Earth's surface. Can you see the hurricane? It appears as the white swirl of cloud on the picture.

Next furthest out is Mars, the red planet. We know quite a lot about Mars. Many spacecraft have been sent to Mars to take photographs and some spacecraft even landed to take samples of the soil.

We cover some extra information on Mars because the learners need to search for information when they carry out a case study of the Mars rover in Unit 4.

Mars needs almost two Earth years to complete one orbit around the Sun, so if you lived on Mars you would have to wait a very long time for your birthday. Mars spins like the Earth, and a day on Mars is almost the same length as a day on Earth. A day on Mars is called a sol.

Can you see the long, darker mark across the surface of Mars? This is a deep valley.

This planet is further from the Sun than Earth, and for this reason it is very cold. It has a thin atmosphere but this atmosphere is mostly carbon dioxide gas. Humans cannot breathe that atmosphere.

The surface is mostly sand and rocks. The sand is full of iron oxide, which is the same substance as red-orange rust. From Earth we see Mars as a small red-orange dot in the sky, because of the colour of the soil.

This is a very recent photograph of the surface of Mars, taken in 2012 by the rover called Curiosity. Can you see all the rocks?

There are some very big valleys on Mars. Valleys are caused by erosion when water flows downhill, so we can make an inference that there was a lot of water on the planet long ago. If there was water, perhaps there were living things on Mars too. But we cannot be sure. Scientists have sent another spacecraft to look carefully at the rocks and sand. The spacecraft is called Curiosity and it will try to find signs of living things in the ground.

This is a closer view of the valley you saw on the surface of Mars. On Earth, valleys like this are caused by water. Did Mars have water long ago?

Mars is smaller than Earth and if you went there, your weight would be only about a third (1/3) of your weight on Earth.

If your mass is 45 kg on Earth, you weigh 450 newtons (N). If you went to Mars, what would you weigh?

450 newtons \div 3 = 150 N. So the answer is 150 N. Show this calculation on the board and explain how to do it.

In fact, your weight on Mars would be 37,7% of your weight on Earth. We have rounded the number to simplify the calculation. If learners query this then you can show them the following calculations: 450 newtons \times \dfrac{\text{37,7}}{\text{100}} = 169.65 newtons

Would you feel heavier or lighter on Mars?

You would feel much lighter on Mars!

Now we have to go very far from the Sun, 5 times further than Earth is from the Sun. We begin to see the gas giants, which are the four outer planets. These gas giants have no solid surface we could land on. They are huge balls of gas and if we came close we would fly through clouds of cold gases.

Jupiter is the first gas giant we come to, and it is the biggest of all the planets. From Earth we see it shining white but close up, its colour is light pink-brown. It is bigger than all the other planets put together.

Jupiter, showing the swirling light pink and brown colours on the surface.

Jupiter is a huge ball of gases such as hydrogen, with clouds of ammonia. Winds blow from east to west on Jupiter's surface, and they blow at the speed of jet planes. The surface is very cold, and some of the gases are so cold that they have become liquid or solid.

Deep inside, Jupiter may have a very hot core of rock. Jupiter has four big moons, and sixty smaller ones.

If we now go even further into Space, to double the distance we went to reach Jupiter, we reach the planet Saturn. Saturn is almost as big as Jupiter but it has a light yellow colour. It is mostly gas and it has rings of rock spread out and spinning around it. Saturn has about 62 moons.

The above image is an artist's drawing of the Cassini spacecraft approaching the planet Saturn and its magnificent rings.

Then we get Uranus, a smooth blue-green ball of gas, with almost no marks and shapes on it that we can see. It has more than 25 moons.

The blue globe of Uranus shown here with 5 of its major moons.

Now we are more than 30 times further from the Sun than Earth is, and we see the last planet, Neptune. Neptune is also a ball of gas and looks like Uranus. It has about 12 moons, and possibly more. Neptune has a very 'stormy' surface. Images of the planet often show huge storms and winds.

Look at this close-up of the surface of Neptune. Can you see the stormy surface? These are the darker blue and white spots.

The following activity tests comprehension skills. It is a good idea to read through the text together and then allow learners to go back and read it by themselves when looking for the answers.

Comprehension on the 8 planets of our solar system.


  1. We have read a lot about the planets in our solar system.
  2. Use all the information and images in the previous pages to answer the following questions.


Name all the planets in order starting from the one closest to the Sun.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune, Uranus

What are the 4 inner planets known as?

The inner, rocky planets

What are the 4 outer planets known as?

The 4 outer planets are known as the gas giants.

Which planet is the hottest?

Venus is the hottest planet.

On which planet do scientists think there might have been water long ago? Why?

On Mars, because there are valleys on the surface which look like they have been made by water erosion.

Which planet has a "stormy" surface?

Neptune has a stormy surface.

Venus also has an atmosphere like Earth, but we would not be able to breathe there. What gases make up the atmosphere on Venus?

carbon dioxide and sulphuric acid

Below is an image showing the temperatures of the planets. Mercury is the closest to the Sun, but Venus is actually hotter than Mercury. This is because of the dense atmosphere of Venus which acts like a greenhouse and traps the Sun's energy in the atmosphere. Use the image to give the temperatures of Earth, Jupiter and Neptune.

The temperatures of the planets

Earth: 15 C

Jupiter: -110 C

Neptune: -200 C

Which is the biggest planet in our solar system? What colour is it?

Jupiter, pink-brown

Which planet is blue-green in colour?


Saturn has rings around it. What are these rings made of?

Draw a picture of Saturn in the space below.


What a strange word - asteroid! Have you heard this word before? Maybe when we mentioned the asteroid belt?

Let's find out what they are!

The asteroids are lumps of rock from planets that broke up long ago. Some of the lumps are bigger than a school building and some are only as big as small stones. They orbit around the Sun and so they are travelling very fast. Some of them are travelling as fast as 25 kilometres every second. That is much faster than a bullet.

This is a photo of the asteroids Ida and Gaspra. Ida is the bigger one and is 30km long.

The asteroids have gathered together in a ring in the solar system. This ring is called the asteroid belt.

Where is the asteroid belt?


  1. Find the asteroid belt in the picture below.
  2. Write out the whole sentence below and complete it.
  3. Use some of the words from the box.

Word box




pieces of rock

in orbit

the Sun

Asteroids are _____ that move _____ around the Sun. The asteroid belt is in Space between the orbit of _____ and the orbit of _____.

Pieces of rock, in orbit, Mars, Jupiter

In 1973, Pioneer 10 was the first spacecraft to travel to Jupiter. To get there, Pioneer 10 had to go through the asteroid belt. Do you remember how fast asteroids are moving? If an asteroid had hit Pioneer 10, the spacecraft would have been destroyed and smashed to pieces. However, Space is a very big place and the asteroids are usually far apart. Pioneer 10 got through safely and went on to take the first close-up photos of Jupiter.

An artist's painting of the Pioneer 10 spacecraft near Jupiter after it was the first to cross the asteroid belt.


You know from the section on planets that other planets have moons.

Earth's Moon

Let's begin with Earth's Moon. You learnt about Earth's Moon in Gr. 4. So what do we already know about Earth's Moon?

Let's revise what we learnt in Gr. 4 about the Moon.


Does the Moon make its own light? Explain how the Moon gives us light at night.

The Moon does not have energy like the stars to make its own light; the Moon is like a white wall that reflects light from the Sun, and the Earth gets some of that light.

Can we see the Moon during the day?

Yes, on some days. But if they are unsure, don't give them the answer. Let the learners debate this or vote on it, and then agree to go and observe. They might have to look every day, for up to two weeks, before they see it.

Does the full Moon look bigger when it rises at supper-time, and then smaller when it is high in the sky?

If they disagree on this, tell them that they can do an investigation - see below.

Why does the Moon sometimes look like a letter D or a letter C?

We see only the part that the Sun is shining on. They learnt this in Gr. 4 workbook.

Is it easier to see the stars when the Moon is full or when it is not full?

It is easier to see the stars when the Moon is not full.

Why do we sometimes see the new Moon looking like this, in the next photo. The Sun is almost behind the Moon, so where is the light coming from?

The light on the Moon is coming from the Earth; the Earth is reflecting the Sun's light.

Only one side of the Moon in this photo has light on it. Where is this light coming from?

Compare the Moon with the Earth


  1. Work with a partner or in a small group.
  2. Look carefully at the picture and answer the questions.
The Moon and the Earth - showing the difference in size


List all the differences you can see between the Earth and Moon.

The Earth is bigger than the Moon. The Moon has craters, but few craters are still visible on Earth (due to wind and water erosion).

The Earth has water in seas, the Moon has none; Earth has areas where green things are growing - there are none on the Moon; clouds on Earth, but none on the Moon.

List some differences that you know about, even though you can't see them in the photos.

The Earth has plants and animals, but there aren't any on the Moon. Earth has an atmosphere, but the Moon does not. The Moon gets very hot and then very cold; Earth's temperatures stay in a range where things can survive. You are heavier on the Earth than you are on the Moon.

Many people say that the full Moon looks bigger when it rises just after sunset, and then looks smaller late at night. Is this true? Let's do an investigation to find out.

The following investigation needs to be carried out on a night when the Moon is full. Come back to it at a later time in the month if you have to wait awhile and carry on with the rest of the content in the meantime.

Does the Moon look bigger when it rises than when it is high in the sky?

AIM (What you want to find out):

HYPOTHESIS (What you think will happen):


  • You need to know the date when the Moon will be full.
  • a piece of wire shaped like a V (you can make this from a paper clip)
  • a ruler


  1. Just after sunset on the right date, look for the rising Moon.
  2. When you see it coming up behind some trees or buildings, hold out your width-measure as you see in the picture below.
Hold your width-measure at arm's length.
  1. Bend the wires until the points (the tips) of the wire touch the sides of the Moon. You must keep your arm straight while you measure the Moon. Can you think of the reason why?

The arm is part of the measuring instrument, because it is an unchanging length! If the child moves her hand closer to her face, the V-shaped measure will give smaller measurements.

  1. Go inside and use a ruler to measure how far apart the tips of the width-measure are.
  2. Record your measurement in millimetres.
  3. Go outside again about two hours later and measure the width of the Moon a second time. Remember to keep your arm straight while you measure.
  4. Come inside and use the ruler again. Measure the distance between the tips on your ruler again.
  5. Record your measurement in millimetres.


Width of the Moon when it was touching the trees: _____ mm

Width of the Moon when it was high in the sky: _____ mm

How could you have done this investigation better?

Most of them will find that the measurements are the same. Some learners will have made mistakes and will say that the high Moon was smaller, so you can ask for a show of hands - "who found that the measurements were the same at 6:00 and 8:00 p.m.?" Now in science, ideas cannot be tested by majority vote. In science, just one careful investigation can undo a majority opinion. If other people can investigate the idea and get that same measurement, then an idea can be changed or confirmed. You can ask the class to go and repeat the investigation tonight. The Moon will still be full, but will rise about 50 minutes later.

CONCLUSION (What you learnt):

Write down a conclusion about what you learnt from this investigation.

They should learn that in science we want to test ideas to find out whether they are true or not. If we measure things, we can sometimes be more certain of the truth.

The Moon has a pale grey surface with dark grey marks on it. Nobody knew what the surface was like until spacecraft landed on the Moon. The first astronauts to walk on the Moon stepped into fine, powdery dust. They collected rock samples (small pieces) to bring back to Earth.

The surface of the Moon is covered with holes called craters. These craters are made by space rocks that hit the Moon. These rocks may be as small as grains of sand or as big as a house. They travel so fast that they explode when they hit the Moon, and they make a round hole.

The footprint of the first person to ever stand on the Moon
The surface of the Moon - can you see all the craters?

The light-coloured areas on the Moon are mountains, and the darker areas are plains. Some of these plains were made by huge space rocks that made craters 300 km wide. Other plains were made by volcanoes on the Moon a long time ago. Lava* flowed out from those volcanoes. Nowadays the Moon has no volcanoes.

The Moon has no air so there is no wind to blow the dust. The Moon has no water, so there is no rain to wash away sand and cause erosion. That is the reason why we see the craters on the Moon so clearly.

Moons of other planets

Other planets have moons, too. Below is an image showing some of the moons in our solar system. Not all of them are shown here. They have been scaled to be the correct size compared to Earth and our Moon.

Mars has two moons, and astronomers called them Deimos and Phobos. Phobos has deep craters showing that it has also been hit by fast-moving rocks. Can you see how small these moons are compared to our Moon?

On the other hand, Jupiter has 66 moons which we have identified, and each time humans send another space probe to Jupiter, more moons are being discovered! Only Jupiter's 4 biggest moons are shown below.

Some of the moons in our solar system

Moons in our solar system


  1. Look at the picture above of the moons in our solar system.
  2. Answer the questions below.


How many moons does Earth have?

Earth has one moon.

What are the names of Mars' two moons.

Phobos and Deimos

Give the name of one of Jupiter's moons.

Io, Europa, Ganymede or Callisto

Pluto is not actually a planet anymore, but it has been classified as a dwarf planet. Pluto also has 3 moons. How many of Pluto's moons are shown in the picture?

Only one of Pluto's moons are shown.

There are two planets which are not listed here as they do not have any moons. Which two planets are these?

Mercury and Venus

What is the name of Saturn's biggest moon?


  • The Sun is at the centre of our solar system.
  • Planets move in orbits around the Sun.
  • Planets cannot produce their own light; they reflect light from the Sun.
  • Asteroids are rocks that move in orbit around the Sun. They are very much smaller than planets.
  • Most of the planets have moons. A Moon is a body which orbits around a planet.

The table below is a comparison of planets and stars. Choose sentences from the box below and write them under the heading "planets". Match your sentences about planets to the sentences about stars.



Stars are very hot balls of gas that give out light and heat.

Planets do not make their own light; they reflect the light from the Sun.

We can see thousands of millions of stars with a telescope.

We can see only 7 other planets in our solar system.

Stars are very, very far away from us.

Planets are not as far away as stars.

Stars do not orbit around our Sun.

Planets orbit around our Sun.

The stars seem to stay the same distance apart always.

Planets change their positions each night, compared to the positions of the stars.

Sentences to select from:

  • Planets do not make their own light; they reflect the light from the Sun.
  • We can see only 7 other planets in our solar system.
  • Planets change their positions each night, compared to the positions of the stars.
  • Planets are not as far away as stars.
  • Planets orbit around our Sun.

If you wanted to find Venus, where would you look? At what time would you look?

Venus can be seen in the west, just after sunset. Sometimes it is visible in the morning, so then you would look in the East at sunrise.

People call Venus the evening or morning star. Explain why Venus is not a star.

Venus appears in a slightly different position each evening at 7:00 p.m, or each morning at sunrise.

Here are two sentences about the solar system. The 2 sentences have been broken and the parts are mixed up. Work with a partner to sort out the parts. Then write out both sentences in your book.
  • The solar system is
  • the Sun.
  • The Sun and all the planets
  • a set of parts that
  • pull on each other.
  • the planets move around
  • pull on each other as

The solar system is a set of parts that pull on each other. The Sun and all the planets pull on each other as the planets move around the Sun.

What made the craters on the surface of the Moon?

Rocks that travel through Space, called meteoroids. They crash into the Moon at very high speeds.

The surface of the Moon has many craters but the surface of the Earth has very few craters. Explain why that is so.

(a) The Moon has no atmosphere to protect it. Earth has an atmosphere so most rocks from space burn up before they reach the ground. (b) Earth has been hit by meteoroids, as the Moon was, but erosion has worn down the craters so that we cannot see them clearly any more.

Neil Armstrong was the first man to put his foot on the Moon. His footprint is still there after 40 years. On Earth, a footprint does not last so long. Explain why it lasts so long on the Moon.

The Moon has no rain and no wind to remove the footprint.

The Earth is travelling through Space at 100 000 kilometres in every hour. How can we work that out? Here is information for you to use: The length of the Earth's path around the Sun is 942 million kilometres and it takes 365 ¼ days to go all the way around. Now you can work it out for yourself.Hint to help you: How many hours are there in one day?

This is a challenge for your learners. They will not be used to working with very big numbers. They will probably need calculators. However, they know what answer they should get.

It is amazing to think that our planet is just one of eight in our solar system, and our solar system is one of millions in our galaxy!

Let's find out about the movement of our planet in our solar system.