Conversation so far:
what is earth's motion around the sun in a path called
The Earth orbits, or revolves around the Sun. This movement is called revolution.
who used a pendulum to test earth's rotation
Léon Foucault was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation.

Question: how long does it take the planet to make one rotation
Self-contained rewrite: how long does it take earth to make one rotation