turning point

On the first day of winter, the tilt of the earth means that the sun directly illuminates the latitude 23.5 degrees south, so less radiation reaches the northern hemisphere - the north pole is in total darkness.

December 21: the first day of winter - the shortest day of the year

The earth in the four seasons in the northern latitudes in relation to the sun. Public domain illustration, from Wikipedia

The summer solstice - a short lesson in astronomy

Cosmic scene with DNA, stars, solvents and atomic circles in oral flow.

Astronomy in ancient times - Babylon 1