One of the best ways of finding planets around other stars is by using the Doppler effect. As a planet orbits its star, the mass of the planet makes the star wobble very slightly, like a slightly out of balance wheel. If this wobble happens to be pointed at us, the spectrum lines from the star will change slightly in frequency (colour) as the star moves closer and then further away. Our model produces a continuous tone from the orbiting planet. As it is spun around, the Doppler effect will become very obvious to the audience as the ball emitting the sound approaches and then recedes from them.
The construction of such a model is relatively simple and would make a great school project for students to undertake.
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