Moon's orbit
Students discover the relative positions of the Earth, Sun and Moon that produce the different phases of the Moon. The orbit of the Moon around the Earth is completed in about a month. Why does the Moon look different on different nights? Based on your Moon Journal can you offer an explanation? What is your evidence?
Materials Required:
• Large hanging lightbulb or a lamp without a shade; this works especially well with a high-wattage bulb, 75 watts or higher
• Styrofoam ball or other spherical object such as fruit that is ~3-4 inches in diameter, one per team
• Sharpened pencil
• Materials to make a moon phase model (any spherical or round shaped items found around the house)
Procedure:
Overview: Students attach a Styrofoam ball to a pencil so that it looks like a lollipop. In this modeling exercise, the ball on the stick represents the Moon, the student represents the Earth and a lightbulb serves as the Sun. Students move the "Moon" around them to discover the different phases. They then create a model to represent the phases of the moon.
1. Assemble the Styrofoam ball (or any available ball) onto a sharpened pencil. Carefully pierce the ball with the pencil to make a "lollipop" out of it.
2. Clear the area around where the lightbulb or lamp is in the room. The light bulb represents the Sun, the "lollipop" represents the Moon, and you student represent the planet Earth. This representation is called a "model."
3. Turn off all the lights and then turn on the model Sun. It is most dramatic if the lights are all off before the "Sun" is turned on.
4. With your face toward the lamp, hold the ball slightly above your head so that you have to look up a little to see it. In this position, you cannot see the lighted side of the ball. This is called a New Moon.
5. Continue standing with your lollipop at arm's length in front of the Sun. Rotate the moon counterclockwise around the Earth (you) so you can see how the movement of the Moon around the Earth makes different parts of the Moon visible.
6. Start by moving the arm holding the ball slightly to the left while still looking at the ball and holding it a little above your head. You will see a sliver of the lighted side of the Moon. This is called a crescent Moon.
7. Keep turning to the left and you will see more of the lighted half of the ball. This is called a quarter Moon.
8. Turn a little more and almost all of the ball will be lit. This is called a gibbous Moon.
9. Keep turning until you see all of the lighted half of the ball. This is a full Moon.
10. Review the Moon Phase diagram. Make sure you understand how each phase is related to the position of the earth and the sun. There are eight phases.
11. Scientists often use their observations in combination with models to develop explanations of scientific events Find objects around your house to make a model, similar to the diagram, showing the eight different phases of the moon. Think about using items such as balloons, marbles, or cream filled cookies. Take a photo of your model to share with the class. Make sure to include the earth and the sun.
Questions:
1. Ask, “Where does the Moon’s light come from?”
2. How does your model provide evidence that the moon’s light comes from the sun?”
3. Using evidence from your Moon Journal observations and from the Moon Phases lesson explain how you know that the phases of the moon occur in a regular pattern.