Modeling a Solar Eclipse

By Marlene Gundlach

When one planet passes between the sun and another body, it casts a shadow called an eclipse. This activity will model a solar eclipse, demonstrating how the shadow of the eclipse if formed.

Eclipses

Just as you create a shadow on the sidewalk when you block the sun, bodies in space can also create shadows. In this activity students will model how these shadows are created in space. The Earth and moon cast long shadows into space. In the shadow where light is totally blocked is a small dark area. This is called the umbra. There is also an area where there is a partial shadow, and some light is blocked and other light fills it in. This area is called the penumbra.

When the moon passes between the sun and Earth, a solar eclipse occurs. The moon's shadow falls on Earth, but only covers a small area because of the moon's size. When the moon moves into Earth's shadow, we have a lunar eclipse. Here, the Earth's shadow blocks sunlight from the moon. All or part of the moon is in shadow.

Modeling an Solar Eclipse

Materials:

• flashlight
• softball
• table tennis ball
• rule
• several sheets of paper

Procedure:

1. Lay the flashlight in the center of a table. Darken the room and turn on the flashlight.
2. Place the softball in the path of the light shining from the flashlight.
3. Place the sheet of paper on the table so the shadow of the softball falls on the paper.
4. Using the ruler, trace the shadow created by the softball.
5. Remove the softball and paper from the table. Place the table tennis ball in the path of the light shining from the flashlight.
6. Using the ruler, trace the shadow created by the table tennis ball on a separate sheet of paper.
7. You will now use the balls to model a solar eclipse. Place the softball on the table in the path of the light from the flashlight.
8. Holding the table tennis ball in your fingers, circle it around the softball. When the shadow from the table tennis ball blocks the light from reaching the softball, an solar eclipse has occurred.
9. Draw the position of the table tennis ball, the flashlight, and the softball at the time of the eclipse.

Questions

1. What was the shape of the shadow created by each of the balls? (Oval)
2. What did the flashlight in your model represent? The softball? The table tennis ball? (Sun, Earth, moon)
3. What was the position of the balls and the flashlight at the time of the solar eclipse? (The table tennis ball was between the flashlight and the softball.)
4. Model a lunar eclipse with the same materials that you used for the solar eclipse model. Write a short paragraph comparing the lunar eclipse and solar eclipse models. (Paragraphs will vary. In the lunar eclipse, the softball will be between the flashlight and the table tennis ball.)