Actually, the Winter Solstice is an astronomical phenomenon marking "the shortest day" & "the longest night" of the year. Winter solstice occurs for the Northern Hemisphere in mid-December & for the Southern Hemisphere in mid- June. As the Earth orbits around the Sun, the same hemisphere that faced away from the Sun, experiencing winter, will, in half a year, face towards the Sun & experience summer. A hemisphere's winter solstice occurs when the sun's daily maximum elevation in the sky is the lowest. The Winter Solstice is also called "Midwinter." The earliest sunset & latest sunrise dates differ from winter solstice, however, & these depend on latitude, due to the variation in the solar day throughout the year caused by the Earth's elliptical orbit.
The solstice itself was probably a cultural event as early as neolithic times, but because there are no written records, historians simply have to guess at that. Historians are convinced that astronomical events, which during ancient times controlled the mating of animals, sowing of crops & metering of winter reserves between harvests, show how various cultural mythologies & traditions have arisen. This is attested by physical remains in the layouts of late Neolithic & Bronze Age archaeological sites, such as Stonehenge in Britain & Newgrange in Ireland.
Newgrange in Ireland
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) & the winter solstice sunset (Stonehenge). At Stonehenge, the Great Trilithon was erected outwards from the center of the monument, with its smooth flat face was turned towards the midwinter Sun.
Newgrange in Ireland
The winter solstice may have been important because the people in these early communities were not certain of living through the winter, & had to be prepared during the previous nine months. 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. It was one of the only times of year, when a supply of fresh meat was available. The majority of wine & beer made during the year was finally fermented & ready for drinking at this time.
Since the Winter Solstice is 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 &, in cultures using winter solstice based cyclic calendars, the year as reborn has been celebrated with regard to life-death-rebirth deities or new beginnings. Before the scientific revolution, many forms of observances, astronomical, symbolic or ritualistic, had evolved according to the beliefs of various cultures, many of which are still practiced today.
When Christian sovereigns extended their rule into pagan lands & converted the inhabitants to Christianity, they eased the cultural transition to a new religion by allowing the people to keep most of their major holidays, which they renamed, changed slightly, & sanctified as Christian holidays. When Christianity developed in the ancient Roman world, the winter solstice in that culture was already marked around 25th December.
Though he was called “King,” Herod I (or Herod the Great, as he liked to be called) was really a Roman governor over Israel and Judah.
Early Christians celebrated the birth of the Savior for the first 3 1/2 centuries on March 25. The date of Christ's birth is nowhere mentioned in the Gospels or by tradition. The Bible, astrology, & a tax collection census offer a few clues. The gospel of Matthew states that Jesus was born "in the days of king Herod." The book of Josephus notes that Herod, King of Judea, died after ruling 34 years de facto, 37 years de jure. Josephus states that an eclipse of the moon occurred not long before Herod's death. A eclipse occurred from 12 to 13 March, A.U.C. 750, so that Herod must have died before the Passover of that year which fell on 12 April. As Herod killed the children up to 2 years old, in order to destroy the new born King of the Jews, Jesus may have been born about 2 years before Herod's death. The tax enrollment under Cyrinus mentioned by St. Luke in connection with the nativity of Jesus Christ, and the remarkable astronomical conjunction of Mars, Jupiter, & Saturn in Pisces, occurred in the spring of A.U.C. 748. (A.U.C. stands for Ab Urbe Condita, meaning "from the foundation of Rome." The Roman A.U.C. calendar was enforced under the penalty of death throughout the Roman Empire during that time.
Pope St. Julius 1 (337-352)
The adoption of the date of December 25 by Pope St. Julius 1 (337-352) was primarily a means by which the early Church could insert itself into many of the popular mid-winter festivals which already were observed by "the pagans" - particularly the celebration of the Roman sun god, Mithras; since 274, under the emperor Aurelian. Rome had celebrated the feast of the "Invincible Sun", Natalis Invicti Solis, on December 25. Other festivals that were appropriated included the Roman Saturnalia celebrations (which changed dates, originally December 17-19, later December 17-23, & finally December 1-23). During this festival, work ceased, gifts were exchanged, & slaves ate with their masters. The festivals of northern Europe, particularly Yule, & also other customs such as yule logs, holly, ivy, mistletoe, candles, evergreens, became part of the Christmas celebration.
Since there was only a loose Christian authority limited by distance & rival power centers at the time, it took centuries before the tradition was adopted geographically:
- Eastern churches began to celebrate Christmas after 375 CE.
- Ireland started in the 5C
- The church in Jerusalem started in the 7C
- Austria, England & Switzerland in the 8C
- Slavic lands in the 9C & 10C