Learn and demonstrate the phases of the moon
Discovery Place Science
The sun, the earth and the earth’s moon have a very special relationship that affects just about everything in our daily lives: the weather, tides, seasons, plants, insects, mood, the food we eat and much more. People have been tracking the sun and the moon for a long time and we have come to understand a lot about how they each move, along with how the earth moves.
In this solar system activity, we will explore that movement and begin to consider how it affects what we see in the sky every day. As we model the phases of the moon through an entire lunar month, you will become the earth-moon-sun system. Using a model of the earth, moon and sun, you will experience the phases of the moon and explore how the moon’s shape changes in predictable patterns. Finally, you can even demonstrate solar and lunar eclipses using this model.
This activity will take about 15-20 minutes of preparation time and another 30-45 minutes of learning time. It is best suited for children in grades 2-8.
- Floor lamp (without lamp shade)
- 1 clear light bulb (40-75 watt)
- 1 extension cord
- One 2 to 3-inch polystyrene (foam craft) ball with a hole large enough to fit a pencil (per learner)
- One pencil to attach and hold polystyrene ball (per learner)
1. Ready your room. For this activity you will need a dark room, preferably one without windows, but any room you can darken in your home will work. If you cannot do this activity at night, use curtains, cardboard or black paper to darken your windows. Using an extension cord, plug the lamp into the center of the room. Tape the cord to the floor using duct tape to help prevent tripping. Have balls and pencils ready to give to each learner.
2. Make moonballs. Create a hole in each ball large enough for the pencil to fit in. The pencil does not need to go in more than one inch. If you are having trouble keeping the pencils attached, you may glue them in place. However, this is not necessary.
3. Test the room. Place your bulb in the lamp and darken the room. Turn the lamp on and hold a moon ball in your hand. Move it to your side observing the crescent shape. Make sure you have good contrast between the light and dark side. Experiment with brighter or dimmer bulbs if necessary.
1. Consider what you may already know about the moon. Have you noticed anything about how the moon changes in the sky? The shape of the moon in the sky changes over time. These changes are called moon phases.
What do you think causes the phases of the moon? (There are no wrong answers here, as long as we are trying to explain something using what we can observe. The goal of this activity is for you to discover the cause of moon phases on your own and form your own explanation.)2.
2. In your darkened room, slowly circle around the lamp. You should have about one body length between you and the lamp as you circle. Take a few minutes to explore and experiment making shadows with your learners and discuss how shadows are formed. A shadow is formed when an object blocks the path of light. (Exploring shadows first will help us understand that the moon blocks light from the sun casting a shadow on itself.)
3. You are now going to model the earth-moon-sun system using a moonball to represent the moon, the lamp to represent the sun, and your head will represent the earth. (To take this model even further, use the tip of your nose to represent your home address.)
Begin by staying in place and moving your moonballs around in the light from the lamp or “sun.” What are you discovering about your moon and its shadows?
4. Now let’s model each moon phase with our objects. Since the moon orbits around the earth and it takes about 1 month, we will mostly be moving the moonball around us (the earth).
How many phases of the moon do you know? (The phases of the moon are new moon, waxing crescent, 1st quarter, waxing gibbous, full moon, waning gibbous, 3rd quarter, waning crescent, new moon.)
A. Crescent moon phase: Hold your moon directly in front of you and move the moon ball slowly to the left until you see a small bright crescent shape illuminated on your ball. This is the crescent moon phase. Which side of the moon is facing the sun? What’s causing the shadow on the moon?
B. Quarter moon (1st) phase: Continue slowly moving your moons to the same direction until half of your moon is lit up from Earth’s point of view (your head). This demonstrates the quarter moon phase. Which side is facing the sun? The light or dark side? As your moon becomes more lit up, is your moon getting closer to the sun or further from the sun?
C. Gibbous moon phase: Continue moving, or “orbiting” your moonball slowly in the same direction. Stop when there is only a small portion of your moon phase in the shadow. This is the gibbous moon phase. Is the moon further from the sun or closer? More lit or less lit?
D. Full moon phase: Continue slowly orbiting the moon in the same direction until the entire moon (what you can see from Earth) is lit up. This is the full moon phase. Is there still a shadow on the moon? Yes. Where is it? Now that the moon is full, where is it compared to the position of earth? The sun? During a full moon, the Earth, moon and sun are directly lined up and the Earth is in between them.
*You may have to hold the moon just above your head so the moon does not pass into your shadow (that would be a lunar eclipse).
E. Gibbous moon phase: Continue orbiting your moon in the same direction until you reach a gibbous moon again.
F. Quarter moon (3rd) phase and crescent moon phase: Continue orbiting the moon in the same direction until you reach a quarter moon phase again. Then the crescent moon phase. As the moon is getting closer to the sun does it appear fuller or less full?
G. New moon phase: Continue moving your moonballs until it is entirely in its own shadow. This is a new moon. The moon cannot be seen in the sky at all. When the moon is new, where is it when compared to the Earth? To the sun? During a new moon, the sun, moon and earth are directly lined up with the moon in between them.
5. You can now model and entire lunar month (one complete moon circle, or orbit, around the earth- approximately 29.5 days. Because we know this pattern repeats every month, we can predict the phases of the moon). Start at a new moon phase and move through each moon phase again. Look for these changes as you perform your orbit:
- Waxing: As the face of the moon that we see from Earth becomes larger it is said to be waxing. During the waxing phase the moon is getting further from the sun on its orbit.
- Waning: As the face of the moon that we see from Earth becomes smaller it is said to be waning. During the waning phase the moon is getting closer to the sun.
Helpful hint: When the moon is waxing, it forms a D shape. When the moon is waning, it forms a C shape. Despite our view from Earth, one half of the moon is always lit up – the half facing the sun. However, we see different amounts of the side that is lit up depending on the alignment of Earth with the moon and the sun.
How to adjust for younger and older learners
For younger learners, focus on teaching them about shadows. Using their hands and the lamp, allow younger learners to experiment with making shadows of different sizes in shapes. Once they’ve had enough practice, instruct them to make some different shadows. Can they make a long shadow? A short shadow? A big shadow? A small shadow?
Ask them what cause the different sizes and shapes of their shadows? (Answer: The position and size of the object.) Ask your learners if there are any large objects in the sky that could make a shadow. (Answer: Yes. The moon.)
Give your learner a moonball and ask them to make a shadow. Explain to them that the dark side of the moon is also a shadow.
For older learners, turn their attention to solar and lunar eclipses.
Solar Eclipse: Ask your learners to move their moon ball directly in front of the lamp (sun), so the moon is blocking the light creating a shadow on their face. Ask them what moon phase they are making. (A solar eclipse happens when the moon moves in front of the sun, casting a shadow on a small portion of the Earth. A solar eclipse can only happen during a new moon phase.)
To view the solar eclipse, your learners will have to look at the faces of the other learners, or the facilitator who is participating in the activity. Remember, the learner’s head represents Earth so the shadow on the faces of the participants represents the area on Earth the eclipse would be happening from. Ask some probing questions. If the shadow is over your eyes, would the folks who lived on your nose or your ears be able to view the eclipse? (Answer: No. The people everywhere else would still see the sun!)
Lunar Eclipse: Ask your learners to move their moonballs to the full moon phase. Their moonball should be directly opposite their body from the sun. Instruct your learners to lower their moonball until it is in the shadow of their head (the Earth). (A lunar eclipse happens when the moon moves into the shadow of the Earth created by the sun.
Instruct students to move their moon in and out of the eclipse. They may observe the shape of their shadow on the moon. Since the Earth is round, it projects a curved shadow on the moon. Unlike a solar eclipse, a lunar eclipse is visible to anyone on Earth.
Over the moon about this activity? Check out this video demonstration of the moon phases for more.