Traditional Chinese Calendar

Zeus Sensor uses the Traditional Chinese Calendar as the base for its calculations. This calendar is different than the Gregorian (Western) calendar because it is influenced by both the moon and the sun, technically called a "Lunisolar" calendar. Without getting too deep into the inner workings of the calendar, the following is a brief introduction to its main concepts and why it is used.

12 Lunar Months

A lunar year has 12 lunar months or cycles. A complete lunar cycle begins with a new moon (fully dark) to a full moon in the middle of the cycle, the moon then wanes towards the next new moon to start the next cycle. Each cycle takes about 29.5 days to complete. The first day of the lunar year begins with the first new moon of the first lunar month, which typically takes place between January 21 and February 20 in the Western Calendar. The 12 lunar months, however, do not precisely align with the 365 days of the solar year (29.5 x 12 = 354 days), therefore the Chinese developed a system of leap months to maintain balance. Within a 19 year period, there will be 7 years that will include an extra month.

24 Solar Terms

The Chinese use something called the Farming Calendar to help regulate agricultural activities throughout the year. This calendar dates back more than 4,000 years and is still in use today. The year contains the 4 seasons, with 6 sub-seasons each to give a total of 24 Solar Terms. These terms indicate the changes in temperature and weather conditions so that the farmers of rural China can plan the dates for ploughing, planting, harvesting, etc. The first solar term is called the Beginning Of Spring.

The 24 Solar Terms of the Chinese Farming Calendar

Chinese Pinyin

Chinese Name

Approximate Gregorian Date

English Name


Five Elements

Li Chun


February 4

Beginning of Spring

Tiger; First

Yang Wood

Yu Shui


February 19

Rain Water

Jing Zhe


March 6

Waking of Insects

Rabbit; Apricot

Yin Wood

Chun Fen


March 21

Spring Equinox

Qing Ming


April 5

Pure Brightness

Dragon; Peach

Yang Earth

Gu Yu


April 20

Grain Rain

Li Xia


May 6

Beginning of Summer

Snake; Plum

Yin Fire

Xiao Man


May 21

Grain Full

Mang Zhong


June 6

Grain in Ear

Guava or Pomegranate

Yang Fire

Xia Zhi


June 22

Summer Solstice

Xiao Shu


July 7

Lesser Heat

Sheep; Lotus

Yin Earth

Da Shu


July 23

Greater Heat

Li Qiu


August 8

Beginning of Autumn

Monkey; Orchid

Yang Metal

Chu Shu


August 23

End of Heat

Bai Lu


September 8

White Dew

Chicken; Osmanthus

Yin Metal

Qiu Fen


September 23

Autumn Equinox

Han Lu


October 8

Cold dew

Dog; Chrysanthemum

Yang Earth

Shuang Jiang


October 24

Descent of Frost

Li Dong


November 8

Beginning of Winter

Pig; Good

Yin Water

Xiao Xue


November 22

Lesser Snow

Da Xue


December 7

Greater Snow

Rat; Winter

Yang Water

Dong Zhi


December 22

Winter Solstice

Xiao Han


January 6

Lesser Cold

Ox; Last

Yin Earth

Da Han


January 20

Greater Cold

Modern day use

Together, these lunar and solar concepts form the Traditional Chinese Calendar. Today it is still used in Chinese culture (and many other Asian cultures) to indicate the dates of national holidays and festivals. Because the ancients used this calendar during the development of Eastern astrology, therefore we adhere to the same practice with Zeus Sensor today.