Happy New Year -- But Why Now?

Happy New Year! Out with the old, in with the new!

Our calendar has its peculiarities, one of the more intriguing being the time of changeover from one year to the next -- 10 days after the winter solstice (the days are finally getting longer again, though it's not too obvious yet) and 4 days before the earth's closest approach to the sun. We must go back in time a few thousand years to see how this anomaly developed.

There are three fundamental cycles of time which are apparent to anyone who has spent any time out of doors. One is the daily cycle of light and darkness, the second is the cycle of the seasons, which is linked to the apparent movement of the sun among the stars, and the third is the waxing and waning of the moon. Unfortunately none of these cycles is an exact multiple of any of the others.

The first of these cycles is impossible to ignore except at high latitudes near midsummer or midwinter. There is good evidence that the other two cycles were understood, predicted to some extent, and used as calendars in both the old and new worlds, even before the invention of cities. Stonehenge in England is famous, but the Native Americans had similar if less spectacular observatories for marking the solstices and equinoxes.

The moon calendar was also widely used, but had disadvantages in an agricultural community because a solar year does not contain an even number of moon cycles. A year of 12 lunar months would be about 11 days short of a solar year. One solution, which is used in our calendar, is to define a "month" that is slightly longer than the lunar month of about twenty-nine and a half days. However, certain religious festivals, such as Passover in the Jewish year and Easter in the Christian one, are still tied to the lunar cycle and thus vary in exact date from year to year.

The Egyptians discovered quite early that the flooding of the Nile occurred regularly soon after the last day that the bright star Sirius could be seen just before sunrise. They also developed an accurate solar calendar, with the year beginning at the fall equinox.

A similar calendar was used in Babylonia, where early astronomers developed a new kind of month, based on the movements of the sun against the stars. They defined a group of twelve constellations, called the Zodiac, with months defined by the constellation in which the sun rode. (This would be the one constellation that would not be visible in a dusk-to-dawn watch of the skies.) Again, the year started with the fall equinox, when the sun entered the constellation of Libra. Since the annual cycles of heat and river levels were clearly correlated with the progression of the sun through the Zodiac, it was not too surprising that people assumed that the interaction of sun and stars might influence human affairs as well. (In fact there is no evidence whatsoever that there is any such influence aside from what comes through the seasonal cycles of day length and weather.)

Much later on, the Romans used a confused combination of solar and lunar calendars, starting their year with the spring equinox. When Julius Caesar visited Egypt, he studied the Egyptian calendar, and was sufficiently impressed that he used the Egyptian calendar as a model for a new Roman calendar.

The new calendar was introduced in the year we would call 46 B.C., but at an odd time. The new calendar -- and the new year -- were to start at approximately the winter solstice. This idea might have come from northern Europe, where the first movement of the sun back towards the north was a time of celebration which eventually blended with our modern Christmas. But the Romans had the idea that the proper time to start something was the new moon, and the new moon was ten days after the solstice in 46 B.C.Thus we can thank the Romans that the start of the new calendar -- and our New Year -- are ten days after the winter solstice.

Our year could have started even farther from the solstice. This year, the moon was new December 20. If we started 1988 with a new moon, the new year wouldn't start until January 19.

Have a good year!