Heavenly Stems and Earthly Branches

Heavenly Stems and Earthly Branches

Heavenly stems and earthly branches (or Tian Gan Di Zhi, commonly abbreviated to Gan Zhi) are the basic units of the ancient Chinese astronomical calendar, which originated from the observation of celestial phenomena. "Gan" literally means stems and "Zhi" means branches. There are ten heavenly stems: Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, and Gui, and twelve earthly branches: Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, and Hai. The heavenly stems and earthly branches are combined in a fixed order to form the Gan Zhi chronology, an important means of recording years, months, days, and hours in ancient China. They are still the basic units of the Chinese lunar calendar today. For example, 2022 is the year of Ren Yin with the heavenly stem "Ren" and the earthly branch "Yin", and 2023 is the year of Gui Mao with the heavenly stem "Gui" and the earthly branch "Mao".

In Chinese folk culture, the twelve earthly branches are paired with the twelve zodiac animals (rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog, and pig). Each animal corresponds to a lunar year. For example, the year of Ren Yin is the year of the tiger, and the year of Gui Mao is the year of the rabbit. The Gan Zhi chronology is based on a 60-year cycle, known as a "Jia Zi", reflecting the ancient Chinese belief in the cyclical nature of history. It was also widely used in divination, arithmetic, naming, and other fields.

天干地支

天干地支简称“干支”，是中国古代天文历法的基本计数单位，源自中国远古时代对天象的观测。“干”原指树干，“支”原指树枝。天干有十个，依次为：甲、乙、丙、丁、戊、己、庚、辛、壬、癸；地支有十二个，依次为： 子、丑、寅、卯、辰、巳、午、未、申、酉、戌、亥。十天 干和十二地支按固定的顺序相互配合，组成干支纪元法。干 支纪元法是中国古人纪年、月、日、时的重要方法，直到现 在仍是中国农历纪年的基本单位，例如，2022年是农历壬 寅年，2023年是农历癸卯年。

中国民间又将十二地支与十二生肖（鼠、牛、虎、兔、龙、蛇、马、羊、猴、鸡、狗、猪）相配，与农历年相对应，如壬寅年为虎年，癸卯年为兔年。干支纪年法以六十年为一个周期，称为一“甲子”。这种纪年法反映了中国古人循环往复、生生不息的历史观。此外，天干地支还广泛应用于术数、计数、命名等领域。