Prior to adoption of the Western solar calendar system, China exclusively followed a lunar calendar in determining the times of planting, harvesting, and festival occasions. Though today people in China use the western calendar for most practical matters of daily life, the old system still serves as the basis for determining numerous seasonal holidays. This coexistence of two calendar systems has long been accepted by the people of China.
A lunar month is determined by the period required for the moon to complete its full cycle of 29 and a half days, a standard that makes the lunar year a full 11 days shorter than its solar counterpart. This difference is made up every 19 years by the addition of seven lunar months. The 12 lunar months are further divided into 24 solar divisions distinguished by the four seasons and times of heat and cold, all bearing close relationship to the yearly cycle of agricultural work.
The Chinese calendar - like the Hebrew - is a combined solar/lunar calendar in that it strives to have its years coincide with the tropical year and its months coincide with the synodic months. It is not surprising that a few similarities exist between the Chinese and the Hebrew calendar: An ordinary year has 12 months, a leap year has 13 months. An ordinary year has 353, 354, or 355 days, a leap year has 383, 384, or 385 days. When determining what a Chinese year looks like, one must make a number of astronomical calculations:
First, determine the dates for the new moons. Here, a new moon is the completely black moon (that is, when the moon is in conjunction with the sun), not the first visible crescent used in the Islamic and Hebrew calendars. The date of a new moon is the first day of a new month.