Chapter 5 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

S2.9.5 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

  • 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 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. The Earth in the middle with a ring round it. The ring is the path of the Moon. The Moon sits at the top of the ring. An arrow on the lower right of the ring shows the way the Moon goes. The Sun is on the left. An arrow labelled sunlight goes from the Sun to the Earth. A second arrow goes from the Sun to the Moon. A short arrow labelled moonlight goes from the Moon to the Earth. Labels: Earth, Moon, Sun, sunlight, moonlight. The picture is not to scale.Earth

    1 Draw the Earth in the middle. Write Earth.

  2. The Earth in the middle with a ring round it. The ring is the path of the Moon. The Moon sits at the top of the ring. An arrow on the lower right of the ring shows the way the Moon goes. The Sun is on the left. An arrow labelled sunlight goes from the Sun to the Earth. A second arrow goes from the Sun to the Moon. A short arrow labelled moonlight goes from the Moon to the Earth. Labels: Earth, Moon, Sun, sunlight, moonlight. The picture is not to scale.EarthMoon

    2 Draw a ring round it. Put the Moon on the ring. Write Moon. Add an arrow on the ring.

  3. The Earth in the middle with a ring round it. The ring is the path of the Moon. The Moon sits at the top of the ring. An arrow on the lower right of the ring shows the way the Moon goes. The Sun is on the left. An arrow labelled sunlight goes from the Sun to the Earth. A second arrow goes from the Sun to the Moon. A short arrow labelled moonlight goes from the Moon to the Earth. Labels: Earth, Moon, Sun, sunlight, moonlight. The picture is not to scale.EarthMoonSunsunlight

    3 Draw the Sun on the left. Draw arrows of sunlight to the Earth and the Moon.

  4. The Earth in the middle with a ring round it. The ring is the path of the Moon. The Moon sits at the top of the ring. An arrow on the lower right of the ring shows the way the Moon goes. The Sun is on the left. An arrow labelled sunlight goes from the Sun to the Earth. A second arrow goes from the Sun to the Moon. A short arrow labelled moonlight goes from the Moon to the Earth. Labels: Earth, Moon, Sun, sunlight, moonlight. The picture is not to scale.EarthMoonSunsunlightmoonlight

    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.

The Sun on the left, labelled Sun. An arrow labelled sunlight goes from the Sun to the Moon. The Moon sits at the top right, labelled Moon, lit on the side toward the Sun. A second arrow labelled moonlight goes back down and left from the Moon to an eye at the bottom, labelled you. At the bottom are the words not to size. Labels: Sun, Moon, you, sunlight, moonlight, not to size.SunsunlightMoonmoonlightyounot to size
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

The Earth in the middle with a ring round it. The Moon sits on the ring in four places. At the top the Moon is labelled start. On the left it is labelled 1 week. At the bottom it is labelled 2 weeks. On the right it is labelled 3 weeks. Labels: Earth, start, 1 week, 2 weeks, 3 weeks. The picture is not to scale.Earthstart1 week2 weeks3 weeks

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 flat ground line. Above it, on the left, a ball with rays labelled Sun. On the right, a half Moon, lit on the side toward the Sun, labelled Moon. Between them are the words daytime sky. Under the line is the word ground. Labels: Sun, Moon, daytime sky, ground.SunMoondaytime skyground
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.

  1. Draw a mark on the ball. This mark is the side of the Moon that faces us.
  2. Stand in the middle of the floor. You are the Earth.
  3. Your friend holds the ball. The mark must always face you.
  4. Your friend walks slowly round you in a circle. The mark keeps facing you.
  5. 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 view from above. A circle labelled you is in the middle. A ring round it is the walk. A ball sits on the ring in four places. In every place a short line in the ball points to the middle. The line is labelled mark. Labels: you, mark.youmark

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.

Check yourself

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

  1. How long does the Moon take to go round the Earth once?

    Tap your answer.

    1. Yes, that is right. Full Moon to full Moon takes about 29 and a half days. That is about a month.

    2. Not this one. A day is one spin of the Earth. The Moon takes much longer to go round. Go to S2.9.2. Try another.

    3. Not this one. A year is one trip of the Earth round the Sun. The Moon takes about a month. Go to S2.9.4. Try another.

    See the answer

    About a month

    Full Moon to full Moon takes about 29 and a half days. That is about a month.

    • If you chose B: A day is one spin of the Earth. The Moon takes much longer to go round. Go to S2.9.2.
    • If you chose C: A year is one trip of the Earth round the Sun. The Moon takes about a month. Go to S2.9.4.

  2. Full Moon to full Moon takes about 29 and a half days. How many days is that twice?

    See the answer

    59 days

    29 and a half days twice is 59 days.

  3. Why does the Moon shine?

    Tap your answer.

    1. Not this one. The Moon makes no light. It is like a stone in a torch beam. Try another.

    2. Not this one. The Sun is a star that makes light. The Moon is a ball of rock. Go to S2.9.1. Try another.

    3. Yes, that is right. The Sun lights the Moon. The Moon sends some of the light back, so we see it.

    See the answer

    Sunlight bounces off it.

    The Sun lights the Moon. The Moon sends some of the light back, so we see it.

    • If you chose A: The Moon makes no light. It is like a stone in a torch beam.
    • If you chose B: The Sun is a star that makes light. The Moon is a ball of rock. Go to S2.9.1.

  4. Ravi sees a pale Moon in the afternoon sky. What does this show?

    Tap your answer.

    1. Yes, that is right. The Moon is in the day sky on many days. The bright sky makes it look pale.

    2. Not this one. The Moon does not come out. It is always going round the Earth. Sometimes it is in the day sky. Try another.

    3. Not this one. The Moon never made light of its own. Bright daylight makes the Moon look pale. Try another.

    See the answer

    The Moon is in the sky by day too.

    The Moon is in the day sky on many days. The bright sky makes it look pale.

    • If you chose B: The Moon does not come out. It is always going round the Earth. Sometimes it is in the day sky.
    • If you chose C: The Moon never made light of its own. Bright daylight makes the Moon look pale.

  5. From an earlier chapter

    Which half of the Earth has day?

    Tap your answer.

    1. Not this one. The Moon makes no light. Day is the half of the Earth that the Sun lights. Go to S2.9.2. Try another.

    2. Not this one. Hills do not make night. The Earth turns away from the Sun. Go to S2.9.2. Try another.

    3. Yes, that is right. The Sun lights one half of the Earth. That half has day. The other half has night.

    See the answer

    The half that faces the Sun

    The Sun lights one half of the Earth. That half has day. The other half has night.

    • If you chose A: The Moon makes no light. Day is the half of the Earth that the Sun lights. Go to S2.9.2.
    • If you chose B: Hills do not make night. The Earth turns away from the Sun. Go to S2.9.2.

  6. Draw the Sun, the Earth and the Moon. Add arrows to show how moonlight reaches the Earth.

    See the answer

    An arrow goes from the Sun to the Moon. A second arrow goes from the Moon to the Earth.

    The Moon makes no light. It sends back some of the sunlight to the Earth.

  7. Why do we always see the same side of the Moon?

    Tap your answer.

    1. Not this one. It does turn. Your friend turned once while walking once round you. The Moon does the same. Try another.

    2. Not this one. The Sun lights the far side too. We just never see it from the Earth. Try another.

    3. Not this one. The Moon is a ball. It has a far side that we cannot see from the Earth. Try another.

    4. Yes, that is right. The Moon turns just as fast as it goes round. So the same side always faces the Earth.

    See the answer

    The Moon turns once as it goes round the Earth once.

    The Moon turns just as fast as it goes round. So the same side always faces the Earth.

    • If you chose A: It does turn. Your friend turned once while walking once round you. The Moon does the same.
    • If you chose B: The Sun lights the far side too. We just never see it from the Earth.
    • If you chose C: The Moon is a ball. It has a far side that we cannot see from the Earth.

  8. Amina sees a full Moon tonight. When will she see the next full Moon?

    A line with an arrow from a circle on the left, labelled tonight, to a circle on the right, labelled with a question mark. Under the arrow are the words one whole trip. Labels: one whole trip, tonight, ?.one whole triptonight?
    Tap your answer.

    1. Not this one. That is about a quarter of the trip. A full Moon comes again after the whole trip. Try another.

    2. Yes, that is right. The next full Moon comes after one whole trip. The trip takes about a month.

    3. Not this one. A year is the Earth's trip round the Sun. The Moon goes round the Earth in about a month. Try another.

    4. Not this one. That is half way through the trip. A full Moon comes again after the whole trip. Try another.

    See the answer

    In about a month

    The next full Moon comes after one whole trip. The trip takes about a month.

    • If you chose A: That is about a quarter of the trip. A full Moon comes again after the whole trip.
    • If you chose C: A year is the Earth's trip round the Sun. The Moon goes round the Earth in about a month.
    • If you chose D: That is half way through the trip. A full Moon comes again after the whole trip.

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.

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

No internet tomorrow? Save the whole book as one file (717 KB). It opens on any phone.