Using a laser and some boiling water,

you can show why planets do not appear to twinkle in the night sky. 

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Here's how to show your students why stars twinkle in the night sky!

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A not-all-together sane way of showing a class how retrograde motion works!


This demonstration shows how atmospheric scattering filters 

the colour of the sun during a sunset.

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Read more: Why Are Sunsets Red?

Three ways to show how the space between objects - like galaxies -

is slowly increasing due to the universal expansion. 

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