The winter solstice occurs exactly when the axial tilt of a planet's polar hemisphere is farthest away from the star that it orbits. Earth's maximum axial tilt to our star, the Sun, during a solstice is 23° 26'. More evident from high latitudes, a hemisphere's winter solstice occurs on the shortest day and longest night of the year, when the sun's daily maximum elevation in the sky is the lowest. Since the winter solstice lasts only a moment in time, other terms are often used for the day on which it occurs, such as midwinter, the longest night or the first day of winter.
~ The acrylic painting on canvas in this post: "Sun Shaman Emerging Spirit", 47"x59", © 1980 Norval Morrisseau /Private Collection/