Winter solstice, the shortest day of the year, falls on December 21 or 22 in the Northern Hemisphere. Winter solstice marks that turning point in the year after which the days begin to lengthen and the nights begin to shorten. In the Northern Hemisphere the longest day of the year, summer solstice, falls on June 21 or 22. In the Southern Hemisphere this same day is observed as winter solstice. In the course of human history many peoples have honored the solstices with ceremonies and festivals. Early Christian authorities placed Christmas near the winter solstice in the hopes of replacing pagan holidays clustered on and around that date (see also DECEMBER 25).
The word “solstice” comes from the Latin phrase sol stitium, which means “the sun stands still.” A daily observer of the sunrise will notice that the sun comes up at a slightly different position along the horizon each day. In the Northern Hemisphere, as summer turns to winter, the sun rises a bit further to the south each day. The days grow shorter and the nights longer. Finally, the sun appears to rise over the same point on the horizon for several days in a row. This is the time of the winter solstice, the time when the sun appears to “stand still” along the horizon. In reality, the sunrise still moves on those days, but only very slightly. The actual day of the solstice occurs when the sun reaches its southernmost position along the horizon. This happens on the shortest day and longest night of the year. The following day the sun begins to move north along the horizon, and the days slowly begin to lengthen while the nights shorten. The days continue to grow longer until the summer solstice, after which they begin to shorten again as the sun once more turns southward.
The explanation for this yearly cycle lies in the mechanics of the earth’s orbit around the sun. The earth’s axis, the hypothetical line connecting the North and South Poles, does not meet the plane of the earth’s orbit around the sun at a perpendicular angle. Instead, the earth is tilted 23 degrees to one side. This tilt causes the earth’s exposure to the sun to vary throughout the year.
During one six-month period of the earth’s yearly orbit, the tilt points the NORTH POLE towards the sun. During this period the Northern Hemisphere gradually gains exposure to the sun, while the Southern Hemisphere loses exposure. In the north the days lengthen and the sun crosses the sky more directly overhead, hence the weather grows warmer. Three months after the winter solstice the Northern Hemisphere arrives at the spring equinox, the twenty-four hour period in which night and day are of equal lengths. Night and day are also of equal lengths in the Southern Hemisphere on that same date. There, since the days are growing shorter, the event is called the autumn equinox. In the north the days continue to lengthen and the nights to shorten until the very last day of this six-month period, summer solstice, the longest day of the year.
This situation reverses itself during the next six months. As the earth continues its orbit around the sun, the tilt begins to turn the South Pole towards the sun and the North Pole away from it. This decreases the Northern Hemisphere’s exposure to the sun’s warming rays while increasing the Southern Hemisphere’s exposure. As a result, the days lengthen in the Southern Hemisphere, bringing spring and summer to that zone while the people of the Northern Hemisphere experience fall and winter. The solstices as well as the equinoxes are reversed. The same day on which northerners experience winter solstice, southerners experience summer solstice.
The effect of this yearly cycle increases as one moves away from the equator and is greatest near the Poles, which undergo months of unbroken light or darkness near the solstices. The prolonged darkness may strongly affect those who live in the far north (see also DEPRESSION). Only the people living along the earth’s equator are not affected by this cycle, since the equatorial zones receive about the same exposure to the sun throughout the year. The length of the days and nights does not change at the equator, so seasonal differences all but disappear.
WINTER SOLSTICE IN ANCIENT ROME
According to the Julian calendar used by the ancient Romans, winter solstice fell on December 25. Although for most of their long history the Romans did not celebrate the winter solstice per se, two important Roman festivals fell on either side of this date. SATURNALIA was celebrated from December 17 to December 23. KALENDS, the new year festival, began on January 1 and lasted until January 5.
In the late third century A.D., however, the Roman emperor Aurelian (c. 215-275) added a new celebration to the calendar, the BIRTH OF THE INVINCIBLE SUN. He chose December 25, the winter solstice, as the date for this festival honoring the sun god. In fact, by the late third century the solstice did not occur on December 25. A flaw in the design of the Julian calendar caused this error. The creators of the Julian calendar believed the year to be 365.25 days long. The actual length of the solar year is 365.242199 days. This tiny discrepancy caused the calendar to fall behind the actual sun cycle by one day every 128 years. In 46 B.C., when the Julian calendar was established, the winter solstice really did occur on December 25. By the late third century winter solstice was arriving two and one-half days early. Nevertheless, the twenty-fifth had engraved itself in the minds of the populace as the date of the solstice, and so was retained as the date of the new solstice holiday (see also OLD CHRISTMAS DAY).
WINTER SOLSTICE AND THE DATE OF CHRISTMAS
In the middle of the fourth century, when Christian officials in Rome chose a date for the celebration of the Nativity, they, too, selected December 25. Most scholars believe that they chose this date in order to draw people away from the pagan holidays celebrated at that time of year. In fact, a document written by a Christian scribe later in that century explains that the authorities chose December 25 for the feast of the Nativity because people were already accustomed to celebrating on that date. Moreover, some Christian leaders found celebrating JESUS’ birth at the time of the winter solstice especially appropriate as they considered him “the sun of righteousness” (Malachi 4:2) and the “light of the world”(John 8:12). With the new festival date in place, Christian leaders exhorted the populace to dedicate their midwinter devotions to the birth of Jesus rather than to the birth of the sun.
WINTER SOLSTICE AND OTHER ANCIENT CELEBRATIONS
The people of EGYPT used a slightly different calendar than did the Romans, one in which winter solstice fell on January 6. Egyptians also honored the sun god on the day of the winter solstice. Other Egyptian festivals that took place on January 6 included the birthday of the god Osiris and the birth of the god Aeon from his virgin mother, Kore. As early as the second century Egyptian Christians adopted January 6 as one of their feast days, too. They began to celebrate Epiphany on that day.
Some researchers speculate that the ancient peoples of northern Europe celebrated a festival called YULE around the time of the winter solstice. Other researchers disagree, however, arguing that the festival took place in November.
People who lived in close contact with the natural world and who did not possess modern astronomical knowledge may well have viewed the gradual shortening of the days and the cooling of the weather with apprehension. It is easy to understand why many of these ancient peoples honored the gods on the shortest day of the year and gave thanks for the return of the sun.
In recent years, renewed interest in pagan or “earth” religions in the developed countries has prompted some people to begin celebrating the solstices again. Although we now understand the astronomical mechanisms behind this cycle in the earth’s seasons, our lives still depend on these celestial maneuvers and the seasonal rhythms they create. The new solstice celebrations honor these life-giving processes with ceremony and festivity.