The Chinese calendar

The Chinese calendar is often called a “lunar calendar”. The more accurate word is lunisolar: it sets the months by the Moon and at the same time keeps them in step with the solar year. Almost everything that looks odd about it follows from that double tie.

The basic problem

Twelve lunar months come to about 354 days, the solar year to 365. A purely lunar calendar therefore drifts eleven days through the seasons every year — the Islamic calendar works that way, and there the drift is intended.

A calendar meant to order farming cannot live with that: sowing has to fall in spring. So the calendar is helped along.

The leap month

Roughly every two to three years a whole thirteenth month is inserted. It carries no name of its own but repeats the one before it — a “second fifth month”.

Which month is doubled is not arbitrary; it follows the position of the Sun. A month that contains none of the so-called principal dividing points of the solar year becomes the leap month. It is an elegant solution, because it needs no table but emerges from observation.

The twenty-four sections

Alongside the lunar months runs a purely solar division: twenty-four sections of fifteen degrees of solar motion each, with names such as “Beginning of Spring”, “Grain Rain” or “Minor Cold”.

These sections are the agriculturally useful part of the calendar, and they fall on almost the same day every year — because they have nothing to do with the Moon.

Why the start of the year is not settled

This is where the most common misassignment of the animal signs comes from.

There are two defensible answers, and the schools are divided:

• The New Year festival — the first day of the first lunar month, between 21 January and 20 February. This is the popular start of the year.
• The beginning of spring — the solar section lìchūn, around 4 February. This is the start of the year that most Bazi schools work from.

The two dates lie up to two weeks apart. Anyone born in that period is given a different animal sign depending on the school — and neither assignment is simply wrong. It is only worth knowing which one is being used.

The sixty-year cycle

Above all of this lies the cycle of ten heavenly stems and twelve earthly branches, which repeats only after sixty years. It counts not just years but months, days and double hours as well — and it is the real subject of Chinese astrology, while the twelve animals are only its most visible layer.