Adapted from "Bouncing Sunlight," by Jennifer Edwards, Utah Education Network, 18 September 2002.
In this 10-minute demonstration or 30-minute activity, children ages 8 to 13 investigate the source of the Moon's light. They consider a ball, wrapped in aluminum foil, and experiment with a flashlight to make it appear bright. The children compare the foil-wrapped ball to a Moon globe and discover that the Moon reflects very little of the light the falls on it, but still appears bright. The children may construct their own globe of the Moon to take home with them by gluing a map template onto a tennis-ball. This activity is most effective when conducted in a dark area, such as outdoors at night during Moon in Action or in a darkened room in conjunction with Earth's Bright Neighbor.
What's the Point?
- The Moon shines by reflecting sunlight.
- Models can be tools for understanding the natural world and for helping us to identify more questions.
For the group:
- 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
For each child:
- 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)
For the facilitator:
- Wrap one tennis ball in aluminum foil.
- Construct a globe of the Moon using the grey Moon template and the other tennis ball.
- Provide a dark location for the demonstration. You may wish to conduct this activity outdoors at night, set up off to the side and near the telescopes during Moon in Action, or in a darkened room in conjunction with Earth's Bright Neighbor.
- Provide the two balls, flashlight, tennis balls, scissors, and templates at a table.
- If you would like the children to make their own Moon globes, provide the materials and table space to cut out the template. Alternatively, print out copies of the U.S. Geological Survey tennis ball globe template for the children to take and construct at home.
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?
3. 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.
4. 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.
- Does the "Moon" still reflect light? Yes.
Optional: Invite the children to create their own Moon globes to take home by cutting out a template and gluing it on a tennis ball.