4.Main Content
experiments
The motion of the Moon around the Earth
Class experiment
This shows an everyday example of circular motion, the Moon going round the Earth.
Apparatus and materials
- Chart showing the star pattern
Safety
Read our standard health & safety guidance
Procedure
a Locate the Moon against the background pattern of stars.
b Follow the Moon’s motion by observing its position relative to the stars at different times on the same night, and also at the same time on consecutive nights.
Teaching notes
1 Questions to ask: Is the motion of the Moon around the Earth a natural motion? Is the Moon in equilibrium? Is any force needed to keep it going? Does the Earth attract or repel the Moon?
2 The speed of the Moon is constant but its direction of motion changes constantly, so the velocity is changing. The Moon is not in equilibrium; there must be a force to create this acceleration. The Earth gravitionally pulls the Moon inwards, and keeps it in a stable orbit.
3 Newton’s third law says that the Moon must pull the Earth towards it. This could be linked to the tides, if this has been covered already.