Tomorrow, Saturday 22 Dec 2007 is the Chinese Winter Solstice festival, a day where tang yuan is consumed.

There is a relation between the Chinese Winter Solstice and Chinese New Year such that Winter Solstice must always fall during the 11th month of the Chinese lunar calendar and Chinese New Year day is the 2nd new moon after Winter Solstice. However, the 2nd relation is not always true and it may fail in some years, e.g. in 1985.

There are basically 2 traditional Chinese calendars - the lunar calendar and the astronomical calendar. The lunar calendar is based on the moon phases and is used to determine the date of most Chinese festivals such as Chinese New Year, Mid Autumn Festival, Dragon Boat Festival, etc. The Chinese astronomical calendar, based on solar, however is mainly used for astrology and fortune telling. Only 2 festivals are determined by the astronomical calendar, namely Qing Ming (4 or 5 April) and Winter Solstice (21 or 22 December).

The lunar calendar usually has 354 days a year (sometimes 353 or 355). However, on leap years, 1 lunar month is added thus making it having 384 days (sometimes 383 or 385). The astronomical calendar has 365 days or 366 days just like the Gregorian calendar that we use for official purposes. The starting point (astronomical new year) is usually on 4 February, also known as the Beginning of Spring. Beginning of Spring is the first of 24 mid-solar and solar terms. Both Qing Ming and Winter Solstice are mid-solar/solar terms in the astronomical calendar.

One thing to take note while we celebrate Chinese New Year on the first day of the first lunar month of the new lunar year, the actual astrological sign for the year begins NOT on Chinese New Year day, rather on the Beginning of Spring. In 2008, the Beginning of Spring is on 4 February while Chinese New Year on 7 February. Babies born from 4 February onwards would be born in the Year of the Rat based on this rule.