Common-sense observation: the sphere of the fixed stars

Before light pollution hid most of the stars from the sight of modern urban dwellers, the movement of the night sky was apparent and familiar to every human culture. In the course of a single night, all of the stars and planets appear to sweep across the heavens in great arcs from east to west. In the northern hemisphere, the North Star marks the pole of what appears to be a gigantic sphere carrying all the stars around the earth once every 24 hours. 

When viewed with the naked eye, the vast majority of stars do not change places with respect to one another even over the course of centuries. The natural explanation is that all these stars are points on a single huge sphere: the ‘sphere of the fixed stars’. 

Today, this appearance can be captured by time-lapse photography. The video below is best viewed starting with the northern view at 0:51-1:16 (where the Pole Star is roughly in the centre of the screen. The watch it from the beginning for the views to the west, east and south.  

Commentary. Howard Hotson (January 2024)