♦ Earth Rotation Day is observed every year on January 8 to recognize the pivotal discovery of Earth's rotation on its axis. This day is celebrated to honour Léon Foucault’s groundbreaking experiment. 

♦ The concept of Earth rotation dates back to ancient Greece in 470 BC. However, it wasn’t until 1851 that French physicist Léon Foucault provided concrete proof with his famous pendulum experiment.