Stargazing: New Year’s Day, good time to think about time

By Tom Burns - Stargazing

I trust you didn’t wake up too bleary-eyed this New Year’s Day because it’s the perfect day to muse about time as we celebrate the world’s dumbest holiday. 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?

It’s astronomy, that’s what. 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,” a set of lunar phases, 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 and leap days.

Even our current division of history into the years before Jesus’s birth (BC) and after (AD) is based on a mistake. Jesus (or, more preferably, Yeshua) was probably born 4 to 7 years earlier than our calendar indicates.

The biggest problem is that time must be measured, and we can’t find a good way to do it. Ancient peoples started by using the motion of the sun to determine the day and the phases of the moon to determine their “moonth.” That method worked well enough if the culture wasn’t too complicated, but problems arose as people had to be places at precise times and days. Unfortunately, the moon takes 29.53 days to cycle through one set of phases. If you’re trying to create a calendar, what do you do with the left over .53 day?

The year was probably a later invention. Since Earth orbits the sun in about 365.25 days, the sun appears to move once around the sky in that time. Unfortunately, the lunar month doesn’t divide evenly into the calendar year. If we assume twelve months in the years, we have about .4 of a month left over. What to do?

By Roman times, the lunar-based system was so messed up that Julius Caesar decided to do what any self-respecting autocrat ought to do. He called in his wisest and most knowledgeable astronomers.

They decided to dump the lunar calendar in favor of a calendar based on the motion of the sun alone. Because of all the earlier confusions, what we now call 46 BCE consisted of 445 days divided into 15 months.

This “Year of Confusion,” as it came to be called, was a disastrous year for scheduling chariot payments, but once it was over, the western world settled into a serviceable 365-day calendar with a leap day every four years, at least for a while.

The trouble was that the Julian year was 11 minutes and 14 seconds longer than the solar year. That doesn’t sound like much, but it really adds up over 1600 years. By 1582, the first day of spring had moved from its intended date of March 21 to March 11. Eventually, spring would begin in February. Something had to be done – again.

Pope Gregory XIII did what Julius had done 1600 years earlier. He called in a gaggle of astronomers to revise the calendar. For starters, they suggested dropping 10 days from 1582. On October 4, Gregory simply deleted the 10 days. Thus, the next day was ­– voila – October 15.

He also declared that century years like the 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 was a leap year.

Gregory’s changes took place immediately throughout the Roman Catholic world. Such was the power of the Papacy at the time.

However, England was not a part of the Roman Catholic world. They had recently gone through their version of the Protestant Reformation under Henry VIII.

As a result, his daughter and heir, Elizabeth I, resisted Gregory’s temporal changes. Great Britain and her American colonies continued to let their calendar slide until 1752, sending the spring equinox back to March 10.

During that year, the English-speaking world finally got its calendric act together. The dates between September 2 and September 14 simply ceased to exist.

Chaos reigned. Workers were none too happy with having to pay their monthly bills with three weekly checks. Angry mobs rioted in the streets yelling, “Give us back our 11 days!”

Eventually, everything quieted down, but some things had to change. Poor old George Washington had to change the date of his birthday to account for the new calendar. When history teachers mention the specific date of events before 1752, ask whether the date is given in the Julian or Gregorian calendar. That should give them pause.

Those steps brought the average calendar year to 365.2425 days, just .0003 days off the real solar time. That’s durned close, but not close enough for the time-obsessed 21st 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 1,983 years to set your watch correctly.

In the end, time is a continuum. You will find no magic tick marks on Earth’s orbit to mark off the days. Our calendar doesn’t reflect any reality except the vagaries of solar-system motion, and it does an exceedingly poor job of that.

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 with the irreplaceable moments in between. How’s that for a New Year’s resolution?

By Tom Burns


Tom Burns is director of the Perkins Observatory in Delaware.

Tom Burns is director of the Perkins Observatory in Delaware.