A Moon phases model project helps you show why the Moon looks different during the month. The Moon does not make its own light, so the bright part we see is sunlight reflecting from its surface. By using a ball for the Moon, a globe for Earth, and a flashlight for the Sun, you can see how the same half of the Moon is always lit.
This project makes an invisible space pattern easy to see in the classroom.
Key Facts
- The Moon reflects sunlight; it does not produce its own light.
- One half of the Moon is always lit by the Sun, except during eclipses.
- The 8 main Moon phases are new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, and waning crescent.
- A full Moon happens when Earth is between the Sun and the Moon.
- A new Moon happens when the Moon is between Earth and the Sun.
- One Moon phase cycle takes about 29.5 days.
Vocabulary
- Moon phase
- A Moon phase is the shape of the sunlit part of the Moon that we can see from Earth.
- Waxing
- Waxing means the lit part of the Moon appears to grow larger each night.
- Waning
- Waning means the lit part of the Moon appears to shrink smaller each night.
- Orbit
- An orbit is the path one object follows as it moves around another object in space.
- Sunlight
- Sunlight is the light from the Sun that shines on Earth and the Moon.
Common Mistakes to Avoid
- Thinking Earth's shadow causes the monthly Moon phases. This is wrong because Moon phases are caused by the Moon's position around Earth and how much of its sunlit half we can see.
- Putting the flashlight in the center of the model. This is wrong because the Sun should be off to one side so all Moon positions are lit from the same direction.
- Labeling first quarter as a half Moon without explaining it. This is incomplete because first quarter means the Moon is one quarter of the way through its phase cycle, even though we see half of its lit disk.
- Mixing up waxing and waning. Waxing means the bright part is growing, while waning means the bright part is shrinking.
Practice Questions
- 1 A Moon phase cycle is about 29.5 days. About how many days pass between a new Moon and the next full Moon?
- 2 Your model has 8 Moon positions spaced equally around Earth. If one full cycle is 29.5 days, about how many days are between each labeled phase?
- 3 In a model, the flashlight is on the left side, Earth is in the center, and the Moon is on the side nearest the flashlight. Explain why an observer on Earth would see a new Moon.