‘The word solstice is derived from the Latin sol (sun) and sistere (to stand still), because at the solstices, the Sun stands still in declination; that is, the seasonal movement of the Sun's path (as seen from Earth) comes to a stop before reversing direction.’
So, let’s expand a little further:
The rise and fall of the sun’s height above the horizon from one solstice to another is caused by the tilt of the earth’s axis relative to the path of the solar rays, plus the fact that the earth orbits the sun approximately every 365 days. Three questions therefore:
1) Since the earth never stops in the course of its orbit, how can the sun ever appear to stand still?
2) On the other hand, how can the sun 'reverse its path' without there being a brief moment of stillness as the change takes place? In other words, is it possible for something to reverse direction without ever ceasing to move?
3) If it does stand still, how long does the moment of stillness last?