What's the Point?
- 2 tennis balls
- 1 piece of aluminum foil large enough to completely cover one ball
- 1 U.S. Geological Survey tennis ball globe template, The Moon (grey)
- 1 flashlight
- A dark location
- Optional: for older children, have them construct a globe of the Moon using:
- 1 tennis ball (perhaps second-hand and donated by a recreation center)
- 1 U.S. Geological Survey tennis ball globe template, either The Moon (grey) or The Moon: Topography from the Clementine mission to the moon (color)
1. Assemble the children in a group and invite them to solve a mystery: Where does the Moon’s light come from? Show them the foil-wrapped ball and explain that they will use it as a model of the Moon. Hold the foil-wrapped ball so that it is shielded from any ambient light.
- Does the "Moon" shine? No.
- Does the Moon make its own light? The "Moon" does not make its own light, so it appears dark.
- How can we make this "Moon" appear bright?
2. Show the flashlight to the children and explain that it represents the Sun.
- Does the "Sun" shine? Yes — both the real Sun and the flashlight.
- Does the Sun make its own light? Yes it does.
Shine the "Sun" on the foil-wrapped ball and observe what happens.
- How does the “Moon” appear now? Bright.
- Why? The light reflects off of the aluminum foil.
- Where else have they observed this type of reflection? Headlights reflect off of street signs, birthday candles reflect off of a person’s face before he or she blows them out.
3. Have the children consider whether the aluminum-foil wrapped ball is a good model of the Moon.
- In what ways is it a good model? It’s round and a similar color.
- In what ways is it not like the Moon? It’s smaller, and the Moon’s surface is not shiny (metallic).
Explain that the Moon reflects only 7% of the sunlight that falls on it! The Sun is very bright, so even that little bit reflecting off the Moon makes it the brightest object in the night sky when it is up. Offer the Moon globe as a better model for the Moon, and shine the flashlight on it.