Stem and Brach Calendar
The Chinese astrology birth chart comes from Chinese Stem-Branch calendar, which is different from Chinese lunar calendar. Chinese lunar calendar uses the cycle of Moon for the Month and uses the cycle of Sun for Year and Day. The day in the Chinese lunar calendar is the moon day. There is an independent counting system for Day is called Heavenly Stem Earthly Branch, which short name is Stem-Branch. The months using in the Stem-Branch are the solar months, the sun positions on the tropical zodiac.
No one knows who invented the Stem-Branch for Day counting system, but legend has it that characters of Day Stem-Branch were found on the Oracle bones. The Animal names of Stem-Branch were applied into the Month system around 206 B.C. (between the Chin and Han dynasties). The Stem-Branch was applied into the Year system around 164 B.C.
The counting system of Stem-Branch is a 60-day cycle system. There are 10 Stems and 12 Branches. The Stem and the Branch are used together. The Stem is used in front of (on top of) the Branch. The Chinese call them Heavenly Stem and Earthly Branch and use a specific sequence as a counting system for the calendar.
No one knows who connected the 12 animal names with 12 Branches, either. Animal names are easy for people to remember the sequence. 10 Stems and 12 Branches are combined into a cycle of 60 counting systems which begin from Wooden Rat and end with Water Pig. 1999 is the year of the Brown Rabbit which is the 16th of the Stem-Branch system. Year 2000 is the White (Golden) Dragon.
In the counting system, a Yang Stem must match a Yang Branch and a Yin Stem must match a Yin Branch. That's why the Wooden Rat means Male Wooden Rat. There is no female Wooden Rat in the calendar.
Astrology Birth Chart
Chinese Yin-Yang Five-Element scholars applied Stem-Branch to the Five Elements which are Metal, Water, Wood, Fire and Earth. Five Elements can be broken down into Yin and Yang as Yang Wood, Yin Wood, Yang Fire, Yin Fire, Yang Earth, Yin Earth, Yang Water and Yin Water . All the animals are divided into Yin and Yang group. Animals in odd sequence order in the Yang group and the other animals in even sequence order in the Yin group. Each animal contains different Five Elements.
Five-Element scholars know people's Stems and Branches from people's birthday and time. Yearly, monthly, daily and hourly Stems and Branches form an astrology birth chart. Five-Element scholars use Yin Yang Five Elements relationships in the birth chart to predict people's fortune.
Sometimes Chinese call the birth chart as Fill Pillars or Eight Characters. For more information about how to read the birth chart, please read the Lucky Element in the birth chart page.