The phases of the Moon
This Topic is About...
- I will learn why the Moon appears to change shape.
- I will learn why the Moon appears to move across the sky by describing the movement of the Earth and Moon.
- I will make a model to show why the Moon appears to change shape.
- I will record observations in a table.
You’re going to be a science explorer!
Key Words
- crescent
- gibbous
- northern hemisphere
- phase
- rotate
- southern hemisphere
- waning
- waxing
Tap to Learn the Meanings!
- crescent: A curved shape that looks like a thin slice of the Moon.
- gibbous: When more than half of the Moon is lit, but it isn’t full yet.
- northern hemisphere: The top half of Earth, north of the equator.
- phase: The appearance of the Moon based on how much of it is lit.
- rotate: To spin around, like Earth rotating on its axis.
- southern hemisphere: The bottom half of Earth, south of the equator.
- waning: When the lit part of the Moon gets smaller.
- waxing: When the lit part of the Moon gets bigger.
Wonderful! You’re learning key vocabulary about the Moon and Earth's motion.
The phases of the Moon
In space, light from the Sun only shines on the front half of the Moon. Looking at the Moon from Earth, we often see some of the dark half of the Moon. It looks as though the Moon changes shape.
The different shapes are called phases.
The Moon’s phases repeat every 29 days — the same time it takes the Moon to orbit Earth.
When the Moon is further away from the Sun than Earth, we see lots of the light side and only a little of the dark side. This phase is called a gibbous Moon.
A gibbous Moon happens when more than half of the Moon is lit but it is not yet a full Moon.
When the Moon is the same distance away from the Sun as Earth, we see half of each side. This phase is called a first quarter moon because it is a quarter of the way around its orbit.
During a first quarter moon, we see exactly half of the lit side of the Moon from Earth.
When the Moon is closer to the Sun than Earth, we see only a little of the light side and lots of the dark side. This phase is called a crescent moon.
A crescent Moon appears when only a small part of the Moon’s sunlit side faces Earth.
When the light side of the Moon is getting bigger, we say the Moon is waxing.
When it is getting smaller, we say the Moon is waning.
The Earth has a northern hemisphere and a southern hemisphere.
The phases of the Moon look different from the northern and southern hemispheres.
In the northern hemisphere, the waxing Moon appears to grow from the right. In the southern hemisphere, it grows from the left.
These are the eight phases of the Moon.
The Moon phases in order:
- new moon
- waxing crescent
- first quarter
- waxing gibbous
- full moon
- waning gibbous
- last quarter
- waning crescent
The Moon looks different depending on whether you are in the northern hemisphere or the southern hemisphere.
In the northern hemisphere, the lit part grows from the right when the Moon is waxing. In the southern hemisphere, it grows from the left.
A full cycle of the lunar phases takes about 29.5 days — this is called a lunar month.
Let’s Investigate!
Modelling the phases of the Moon
You will need
- a bright light (this represents the Sun)
- a white ball on a stick (this represents the Moon)
Sofia is modelling the phases of the Moon. As she turns, the ball makes a circle around her head. One side of the ball is always in the light. As she turns, she can see different amounts of the lit side and the dark side. In the picture she can see a waxing crescent Moon.
Try this
- Stand facing the light with the “Moon” (the ball) in front of you. This position shows the new Moon.
- Turn slowly to your left while keeping the ball at arm’s length.
- Watch how the shadow on the Moon changes as you turn.
- Say the name of each Moon phase as you see it.
As you turn, you should see shapes such as crescent, half Moon, gibbous, and full Moon.
How am I doing?
Help a friend to observe and name all the Moon phases.
Can they match the correct name to each phase?
Can you both describe what causes the phases?
Show answers
What you should notice
- The Moon phases are caused by the angle between the Sun, Earth, and Moon.
- The part of the Moon facing the Sun is always lit.
- We see different amounts of the lit half as the Moon orbits Earth.
Phases you should see in order
- New Moon
- Waxing crescent
- First quarter (half Moon)
- Waxing gibbous
- Full Moon
- Waning gibbous
- Last quarter
- Waning crescent
Your model should show that the Moon does not change shape—only the amount of sunlight you can see changes.
Moonrise and Moonset
The Moon rises in the east, moves across the sky and sets in the west, just like the Sun. This is not because the Moon is moving. This is because the Earth is turning. We say it rotates. The Earth rotates once every day.
Because the Moon orbits the Earth, the time that the Moon rises and the time it sets is a bit later every day. So, the Moon can be up in the day or the night, but it is harder to see in the day.
The Moon rises about 50 minutes later each day because it is orbiting the Earth.
Let’s Investigate!
Making a Moon diary
You will need
- a table to record your observations
Make a Moon diary by observing and drawing the Moon every day. Record your observations in a table like this:
| Date | Monday 3rd February | Tuesday 4th February | Wednesday 5th February | Thursday 6th February | Friday 7th February | Saturday 8th February | Sunday 9th February |
| Observation | Waxing crescent | Waxing crescent | Cloudy | First quarter | |||
| Rises / Sets | 4.20am 12.00pm |
5.21am 12.50pm |
6.10am 1.49pm |
6.48am 2.55pm |
Find out what time the Moon rises and sets before trying to observe it. It might be on the other side of the Earth! If it is cloudy you may not be able to see the Moon. Draw it as often as you can.
How am I doing?
Did you check the rise and set times each day?
Did you draw the Moon as accurately as you could?
Can you spot a pattern in the Moon’s shape across the week?
Can you explain why the Moon sometimes cannot be seen?
Show answers
What you might notice
- The Moon appears to change shape over several days.
- The phases follow a sequence: waxing crescent → first quarter → waxing gibbous → full Moon.
- Cloudy weather or daylight can make observing difficult.
Example conclusion
“The Moon changed little by little every night. It grew from a thin crescent into a half Moon by Thursday. Cloudy days made it hard to observe, but I could still follow the pattern.”