Demonstrating the Phases of the Moon

Demonstrating the Phases of the Moon

Goals:
Learn about the phases of the moon by using a model to “act out” the movement of the moon around
the Earth, as the Earth circles the sun and how our view of the lighted areas of the moon (the phases
as such) changes.

Materials:
• styrofoam spheres (3 inches or larger) – one per student
• pencil – one per student
• light with a 100 watt bulb (or more) with no shade, so it can shine in all directions. It should be at

head level with students, so may have to sit up on a table.

Procedures:
1. Clear floor space and put the lamp in the middle of the room. It represents the sun.

2. Each student will need to carefully spear the styrofoam ball with their pencil in the center until it
is secure on the pencil. This “styrofoam lollipop” represents the moon. Each student represents the
Earth.

3. Turn out the lights and cover the windows. This activity works best in full darkness.

4. Each student should hold the moon (by the pencil) in one hand. Students should spread out
in a circle around the light giving themselves enough room to rotate 360° without bumping into
other students. They will be rotating (as Earth does) and the moon with them. As the moon changes
position in relation to the sun (the lamp), they will see different amounts of the styrofoam ball (moon)
just like the phases of the moon. Here goes.

New Moon

5. Start facing the light with your “moon” held out in
front of you (between you and the light). How much of the
moon is visible in this position? This is the “new moon”
position and the side facing the Earth (you) should be dark.

6. Next, keeping your arm extended, rotate to the left Waxing
(counterclockwise) 45° watching your moon. Notice that Crescent
you can now see some of the white showing on your moon.
You are in the waxing crescent moon phase.

7. Rotate again to the 90° First Quarter
position from the light (your Waxing Gibbous
side will be facing the light).
Notice there is now more of
your moon in light (about
half). This is the first quarter
moon phase.

8. Another rotation to Full Moon
brings you to a 3/4 moon or
waxing gibbous moon.

9. With your back to the light you should see all of your moon now.
This is a full moon.

10. If you keep rotating in the same direction Waning
with will next see the waning gibbous phase. Gibbous

11. Then the last quarter phase.

12. Then the waning crescent phase.

13. With your next turn you should be facing the light Last
again with a new moon. Quarter

Now you have demonstrated a full month of moon phases.
Can you see how the moon always gets the same amount of sun?
Can you see how we see it from different throughout each month?

Now look at the diagram below. This is a view of the moon phases Waning
from above. This should help you further see how the moon is Crescent
always lit on one side. This never changes. But the position of the
moon as it circles the Earth changes, so we see the lit side from ©Sheri Amsel
different angles throughout the month.

www.exploringnature.org

Phases of the Moon - A Visual Model

Study the diagram below to understand why we see the different phases of the moon throughout each month. Note that:
1. The moon always gets the same amount of sunlight - on just one side.
2. When the moon is between the Earth and sun, we face the dark side, so cannot see the moon - This is the New Moon.
3. When the Earth is between the moon and the sun, we only see the light side - Full Moon.
4. In all the other phases we are seeing the moon’s lit side at an angle, as shown, so only see a portion of the lit side. Note that the waning side looks

upsidedown. That is because you would be seeing the moon from the Earth’s surface (not from out in space the way the diagram is shown).

Waxing First
Gibbous Quarter

Waxing
Crescent

Full SUN
Moon
New
Waning Moon
Gibbous
Waning
Last Crescent
Quarter
©Sheri Amsel
www.exploringnature.org