Put simply, it's the illusion of a stationary Earth caused by observing the night sky. Stars and planets do indeed appear to rotate around us due, of course, to the Earth's own rotation.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'