Solstice

“The winter solstice, also known as midwinter, is an astronomical phenomenon marking the day with the shortest period of daylight and the longest night of the year. In the Northern Hemisphere this is the December solstice and in the Southern Hemisphere this is the June solstice…

More evident from high latitudes, a hemisphere's winter solstice occurs on the day with the shortest period of daylight and longest night of the year, when the sun's daily maximum elevation in the sky is at its lowest… In some cultures it is seen as the middle of winter, while in others it is seen as the beginning of winter. Worldwide, interpretation of the event has varied across cultures, but many have held a recognition of rebirth, involving holidays, festivals, gatherings, rituals or other celebrations around that time…

Many cultural mythologies and traditions such as Stonehenge in England and Newgrange in Ireland are derived from this. The primary axes of both of these monuments seem to have been carefully aligned on a sight-line pointing to the winter solstice sunrise (Newgrange) and the winter solstice sunset (Stonehenge). It is significant that at Stonehenge the Great Trilithon was oriented outwards from the middle of the monument, i.e. its smooth flat face was turned towards the midwinter Sun. The winter solstice was immensely important because the people were economically dependent on monitoring the progress of the seasons. Starvation was common during the first months of the winter, January to April (northern hemisphere) or July to October (southern hemisphere), also known as "the famine months". In temperate climates, the midwinter festival was the last feast celebration, before deep winter began. Most cattle were slaughtered so they would not have to be fed during the winter, so it was almost the only time of year when a plentiful supply of fresh meat was available. The majority of wine and beer made during the year was finally fermented and ready for drinking at this time.

The concentration of the observances were not always on the day commencing at midnight or at dawn, but at the beginning of the pagan day, which in many cultures fell on the previous eve. Because the event was seen as the reversal of the Sun's ebbing presence in the sky, concepts of the birth or rebirth of sun gods have been common and, in cultures which used cyclic calendars based on the winter solstice, the "year as reborn" was celebrated with reference to life-death-rebirth deities or "new beginnings."

The pagan Scandinavian and Germanic people of northern Europe celebrated a twelve-day "midwinter" (winter solstice) holiday called Yule. Many modern Christmas traditions, such as the Christmas tree, the Christmas wreath, the Yule log, and others, are direct descendents of Yule customs. Scandinavians still call Yule "Jul". In English, the word "Yule" is often used in combination with the season "yuletide"  a usage first recorded in 900. It is believed that the celebration of this day was a worship of these peculiar days, interpreted as the reawakening of nature. The Yule (Jul) particular god was Jólner, which is one of Odin's many names. The concept of Yule occurs in a tribute poem to Harold Hårfager from about AD 900, where someone said "drinking Jul". Julblot is the most solemn sacrifice feast. At the "julblotet", sacrifices were given to the gods to earn blessing on the forthcoming germinating crops. Julblotet was eventually integrated into the Christian Christmas. As a remainder from this Viking era, the Midsummer is still important in Scandinavia, and hence vividly celebrated.

Sol Invictus ("The Unconquered Sun") was originally a Syrian god who was later adopted as the chief god of the Roman Empire under Emperor Aurelian. His holiday is traditionally celebrated on December 25, as are several gods associated with the winter solstice in many pagan traditions.”

Holidays celebrated on the winter solstice:

• Alban Arthan (Welsh)
• Blue Christmas (holiday)
• Brumalia (Ancient Rome)
• Dongzhi Festival (Asia)
• Korochun (Slavic)
• Sanghamitta Day (Theravada Buddhism)
• Shalako (Zuni)
• Yaldā (Iran)
• Yule in the Northern Hemisphere (Neopagan)
• Ziemassvētki (ancient Latvia)”

~ Wikipedia