New Year’s Eve is upon us, and thus tomorrow marks the end of the holiday season. It seems a safe time to upset some of you by contemplating some of the misunderstandings that our yearly winter solstice celebration engenders.

Yes, that’s right. All of the holidays celebrated this time of year are derived from an essentially astronomical event and probably began as such.

This year, the winter solstice, the historical start of the holiday season, occurred on Dec. 21. It is an auspicious moment for Northern Hemispherians. For the past few months, the days have been getting shorter and the nights longer. The solstice marks the day of longest night. On subsequent days, daylight begins to return with its promise of eventual springtime.

That astronomical pattern is not lost on us. We use the solstice to mark the beginning of winter. In more northern climes, where cold weather begins earlier, the solstice marks mid-winter.

The longest night leads to the shortest period of daylight, and that’s how most people define the solstice.

However, longer days and spring’s promise are consequences of the solstice and not its defining characteristics. The solstice is in fact a specific astronomical event that happens at a specific moment in time. This year, that moment happened on Dec. 21 at 5:23 p.m.

At that moment, the sun reaches its lowest point in the northern sky. That day, the sun rises farthest to the northeast and sets farthest to the northwest. Its small arc above the horizon ensures that it’s not up for very long.

That’s part of the reason that the temperatures are lower in winter, but it’s only a partial explanation.

The other cause of winter is the fact that Earth’s axis is tilted 23 degrees with respect to its orbit around the sun. Right now, the northern hemisphere is tilted away from the sun and the southern hemisphere is tilted toward it. In the south, the sun is up longer and the sun’s light beats down from higher overhead. That high angle increases the ability of the sun’s energy to heat up the planet. In the north, the sun’s light hits the planet at a more oblique angle and there’s less of it to start with because of the longer nights.

As winter progresses, the sun slowly moves south and rises higher in the sky. We get more daylight and a more efficient angle to receive the sun’s energy. However, it takes months for the atmosphere to heat up sufficiently to create warmer temperatures in our hemisphere.

Many ancient cultures measured the timing of the winter solstice with careful precision. The early months of winter often meant starvation and death. The sun had seemed to desert them. The return of the sun meant eventual salvation from winter’s harsh realities.

As a result, most cultures in our hemisphere have some solstice celebration or another. Christmas is a prime example.

In fact, many of our Christmas traditions predate Christianity to ancient solstice celebrations. The early Christians were clever propagandists. When they made their move into a new region of the world, they often adopted a few harmless customs of the old celebrations. As a result, their beliefs were more palatable to practitioners of the older religious traditions.

Ever wonder why we cut down an evergreen and carry it indoors during the holiday season? Ancient Germanic cultures believed that a tree spirit inhabited the evergreen. Rapping on its bark would release the spirit and bring prosperity to the dwelling. We “knock on wood” to this very day to get the same kind of good luck.

Christianity celebrates the birth of its savior near the solstice, but the timing seems odd. At the birth of Jesus, shepherds were “abiding with their flocks.” In the Middle East, shepherds would most likely do so in the spring when the new lambs were born. The shepherds would stand guard all night to protect the helpless babes from attack by hungry predators.

So why do we celebrate Christmas near the winter solstice? As Christianity spread through Rome, the church elders were likely looking for a Christmas date to replace another solstice celebration — the infamous Saturnalia.

Around the winter solstice, Romans honored Saturn, the Titan who fathered some of the gods, including Jupiter, the king of the gods. During the Saturnalia, Rome went through a reversal of cultural roles.

It was party time! Masters became slaves and slaves masters. Old grudges were forgotten, and the law courts were closed. Notably, gifts were exchanged, a practice we continue to this day.

By the time of the growing Christian Church, criminal acts had become common and debauchery rampant during the Saturnalia. Christians were looking for a replacement, and what better one existed than the celebration of the birth of an innocent child who would go on to save the world?

Now, I don’t mean to sound irreligious here. To their credit, Christians incorporate the best of the religious and cultural practices that surround the solstice. They seem to recognize that long before the birth of their savior, people looked up at the sky in search of succor in a world that begs for answers.

As the time obsessed of you have already noted, the winter solstice occurs on Dec. 22 next year, and not on Dec. 21.

Since the various solstices and equinoxes are determined by Earth’s orbit around our sun, one would expect the solstice to happen at the same moment every year, but it doesn’t.

The problem is not with Earth’s orbit but by our rather inadequate, kludged-together method of measuring the passage of time.

Our year is based on the orbit of Earth around the sun. Our month is loosely based on the phases of the moon. Our day is defined by the rotation of Earth on its axis and the apparent rising and setting of the sun.

The trouble is that none of these astronomical times are evenly divisible into each other. A true “moonth” lasts 29.53 days. A true solar (or “tropical”) year is 365.2422 days, not 365.25 days. As a result, our calendar is a messy hodgepodge of unequal months, leap days, and even the occasional leap second as Earth’s orbit imperceptibly slows down.

The result is that the winter solstice occurs at a precise point in Earth’s orbit around the sun, but our calendar is woefully unable to match the precision of Earth’s orbit.

In fact, our modern calendar wasn’t even invented until 1582. The older Roman calendar year was 11 minutes and four seconds longer than the solar year. That doesn’t sound like much, but it really adds up over 2,000 years. By 1582, the first day of spring on the calendar was falling ten days after the real first day of spring. Something had to be done.

On Oct. 4, 1582, Pope Gregory XIII deleted the next 10 days from the calendar. Thus, the next day was — voila — Oct. 15. He also declared that century years like the seminal year 2000, which would have been leap years, would not be, except of course for years divisible by 400, like (oops) the year 2000, which therefore WILL was a leap year. Confused? Me too.

Those steps brought the average calendar year to 365.2425 days. That’s danged close, but not close enough for the time-obsessed 21th century. The current Time Lords have decided that years divisible by 4,000, which would have been leap years under the “400” rule, now won’t be. That brings the average calendar year to 365.24225 days, but you’ll have to wait 1,982 years to set your calendar correctly.

As a result, our calendar doesn’t reflect any reality except the vagaries of solar-system motion, and it does an exceedingly poor job of that. But we’ll fight every change in it with every ounce of our strength because we THINK the calendar is real.

A case in point: Pope Gregory’s calendar reforms weren’t adopted in England until 1752, when September 3-13 magically ceased to exist. Time-crazed rioters trashed England, all the while chanting, “Give us back our eleven days.”

All of which brings us to today, New Year’s Eve, a time to celebrate the world’s dumbest holiday. Thus I say, “Give me back my Jan. 1.” Everyone (in the northern hemisphere, at least) knows that the year REALLY begins on the first day of spring, the Vernal Equinox, as the sun crosses the celestial equator moving northward and our world explodes with new life.

Those astronomical and natural rhythms are as deeply ingrained in us as sleeping and eating. Our current mid-winter celebration is a violation of our most fundamental instincts.

Who decided that we should begin our year in the dead of winter, anyway? What is it about the annual “dropping of the ball” festival that stimulates excessive drinking and the ritualistic wearing of lampshades?

The truth is that our New Year’s Eve debauch marks the end of the Roman Saturnalia, which was the mother of all debauches.

As for me, I will celebrate by staring with silent wonder at the stars if the sky is clear, but I would have done that anyway. Stay home (and sober), for heaven’s sake. Celebrate instead by going outside on the first truly spring day and reveling in the glories of newborn nature below the horizon and the magnificence of the stars above.

The most important fact about time is that we have so little of it. The universe began the moment you were born, and it will end the day you die. The real meaning of time is what you do in between.