The Celestial Sphere is an imaginary round surface with an infinite radius on which all objects in the sky can be thought to be placed. The concept is used in navigation and an early form of astronomy.
This point of reference is used in basic physics to simplify calculations, and provides results which are accurate enough to use in kinetic projectile modelling. The art of throwing stuff at other stuff relies on the understanding that the celestial sphere was created on day four, and that the stars can be used to measure latitude and longitude. When gyroscopes are employed in the stabilization of moving objects, greater accuracy can be achieved. The combination of gyroscopes and stellar navigation is used in aircraft flight, and in rocket science.