Diurnal motion is an astronomical term referring to the apparent daily motion of stars in "orbit" around the Earth, caused by the Earth's rotation around its axis. It is a rotation around the axis...
That has never been proven, and it's impossible to prove. It's "only a theory". However, in the 16th Century, Johannes Kepler showed that IF that's what's happening, then it would accurately explain...
Lying on your back, looking up, all the stars rotate around Polaris (it will make an ever so slight circle beeing very close to the celestial North Pole - as close as it gets for the next 22 000...
When an object changes its position with respect to time, then the body is said ti be in 'motion'. When the body is at rest, it is state of 'no motion'.