The Nature of Science Activity Modelling the earth-sun-moon system
A model Anything that can be used to represent real objects and the relationships between them.
Fig. 10 on page 399 uses drawings to represent the relative positions of Earth, the sun and the moon during a solar eclipse. Fig. 12 on page 399 shows their relative positions during a lunar eclipse. As representations of real objects, these diagrams are considered to model the relationships between the objects.
Activity Use the diagrams of the solar and lunar eclipses in Figs 10 and 12 to help you to design and make a physical model of the earth-sun-moon system. By changing the relative positions of the objects in the model, you can use the model to show: the cause of a solar eclipse and how a lunar eclipse may be represented.
1. 2.
Any lamp or bright light source can be used to represent the sun. A football or basketball can represent Earth, and a smaller ball such as a table tennis ball can represent the moon.
Activity Modelling the phases of the moon
In this investigation you will use a model of the earth-sun-moon system to examine how the position of the moon affects its phases.
Apparatus Light source, e.g. lamp or torch Football or basketball Tennis ball or other small ball Large sheet of white paper Piece of string (approx. 50 cm) Marker
Method
1. Using the string and marker draw a circle (approx. radius 50 cm) to represent the orbit of the moon. 2. Place the large ball in the centre of the circle to represent Earth. 3. Place the light source about 3 m away from the ball. Make sure that the light source is level with the ball. The light represents the light of the sun. 4. Place the smaller ball at four different points as shown in Fig. 13. 5. Record the phase of the moon that is represented in each position.
