The Chinese calendar dates back centuries before the Julian calendar we use at the present day. It measures time based on the astronomical observations of the movement of the Sun, Moon and stars, and is highly accurate

A calendar is a system for measuring time, from hours and minutes, to months and days, and finally to years and centuries. The terms of hour, day, month, year and century are all units of time measurements of a calendar system.

Distance can be measured with a stick. Time is measured by observing the movements of the sun, moon and stars. People from all cultures have discovered this from pre-history to the present time.

Every one knows about the rotation of the Earth about its axis, which causes (apparent) movement of the Sun from East to West across the sky. So we define one cycle of movement of the Sun as one 'Day.' The Chinese word is very straight forward and calls one day as one 'Sun.'

To define a month, we look at the Moon! Each night, the appearance of the Moon changes. From 'new moon' to 'full moon' and back. So we define a 'Month' as the time it takes for the Moon to go through one cycle of motion. As it happens, this takes about 29.5 days. So we round the month to be either 29 days or 30 days. Again, in the Chinese language a month is simply a 'Moon.'

The next larger unit of measurement of time is the 'Year.' For this we go back to the Sun again. Careful observations reveal that the over a period of many months (12), the position of the Sun shifts from very high overhead to a much lower point at Noon time. The length of daylight time also changes from longer to shorter. Even more importantly, the weather changes from hot to cold, giving rise to the four seasons of Winter, Spring, Summer and Fall.

It is logical, therefore, to define the length of this time period as a 'Year.' Since the word 'Sun' has already assigned the meaning of a 'day', a new word has to be used to denote the 'year.' The Chinese word for 'Year' is 'Nian'.

A year is a little more than 365 days. In 104 B.C. the length of a year was determined to an accuracy of 365.2502 days. By 480 A.D., Ju Chongzhi refined it to 365.2428 days, or 52 seconds more than the modern value of 365.2422 days. To put it another way, in 2,000 years the total discrepancy is less than one day! Together with the voluminous annals of Chinese historians, the Chinese have provided the most accurate and uninterrupted time-line records.

Although 0.24 day does not look like much, over many years it becomes significant. How do we round it to a whole number of days? There are several different schemes to do this. The Chinese scheme is called the 'lunar calendar', and the nearly standard calendar is called the 'solar' calendar system.

In the Chinese Lunar Calendar, a normal year has 12 lunar months, with the length of lunar month defined above. In order to make up to 365.24 days, an extra month is added during the Leap Year.

In the Solar Calendar system, a normal year has 365 years. Every 4-th year, an extra day is added in February to make up to 365.25 days. This is called the Leap Year. Each year still has 12 months, but the number of days in each month vary illogically, so the start of each month does not coincide with the phase of the New Moon at all.

For historical discussions of long periods, longer units of time are handy.

For historical discussions of long periods, longer units of time are handy.
In the Western calendar terminology:
Decade = 10 years
Century = 100 years
Millennium = 1,000 years

In Chinese calendar terminology:
Great Year = 12 years
Cycle = 5 Great Years = 60 years
Epoch = 60 Cycles = 60 x 60 years = 3,600 years

Each year is also designated by one of the 12 animals. For instance, 2003 is the Year of the Ram and 2004 is the Year of the Monkey. This system is extremely practical. A child does not have to learn a new answer to the question, "How old are you?". Old people often lose track of their age, because they are rarely asked about their current age. Every one just have to remember that he or she was born in the "Year of the Monkey" or whatever.

In English, the names of the 12 months are January, February, March, April, May, June, July, August, September, October, November, December.

The 12 animals of the Chinese calendar are: Rat, Ox, Tiger, Hare, Dragon, Snake, Horse, Sheep, Monkey, Rooster, Dog and Pig

The 12 animals of the Chinese calendar are widely adopted and used in the Chinese, Japanese and Korean Zodiacs. The Vietnamese adopted the 12 animals of the Chinese calendar, with the exception of the 4th animal. The rabbit is replaced by the cat.

The Chinese New Year does not fall on the same date each year, although it is always in January or February.