The winter solstice, also called the hibernal solstice, occurs when either of Earth\'s poles reaches its maximum tilt away from the Sun. This happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the winter solstice is the day with the shortest period of daylight and longest night of the year, and when the Sun is at its lowest daily maximum elevation in the sky.Each polar region experiences continuous darkness or twilight around its winter solstice. The opposite event is the summer solstice. The winter solstice occurs during the hemisphere\'s winter. In the Northern Hemisphere, this is the December solstice (December 21, December 22, or December 23) and in the Southern Hemisphere, this is the June solstice (June 20, June 21, or June 22). Although the winter solstice itself lasts only a moment, the term also refers to the day on which it occurs. The term midwinter is also used synonymously with the winter solstice, although it carries other meanings as well. Traditionally, in many temperate regions, the winter solstice is seen as the middle of winter; although today in some countries it is seen as winter\'s beginning. Other names are the "extreme of winter" (Dongzhi), or the "shortest day". Since prehistory, the winter solstice has been a significant time of year in many cultures and has been marked by festivals and rites. This is because it is the point when the shortening of daylight hours is reversed and the daytime begins to lengthen again. In parts of Europe it was seen as the symbolic death and rebirth of the Sun. Some ancient monuments such as Newgrange, Stonehenge, Cahokia Woodhenge and Ahu Tongariki are aligned with the sunrise or sunset on the winter solstice.