Yin-Yang(Lunar&Solar) Calendar: The Philosophy of Astronomy and Harmony
In human observation of nature and cosmology, the relationship between heaven and earth is not just a scientific question but also a cultural philosophy. The Yin-Yang calendar is a system that harmonizes the astronomical movements of the Earth, Moon, and Sun with human life.
Astronomical Systems and the Way of Yin-Yang
Observing the Moon and the Sun from Earth reveals distinct lunar&Solar cycles: the synodic month (from new moon to the next new moon) lasting 29.53 days and the sidereal month (the Moon returning to the same position relative to the stars) lasting 27.32 days, with a difference of 2.2 days. Additionally, the solar year is 365.25 days long. An intricate system of leap years, leap months, and leap days ensures calendar synchronization. Over 19 years, 7 leap months are introduced to balance the alignment of dates and seasonal changes.
The 24 Solar Terms and the Earth-Sun Relationship
The 24 solar terms, derived from the Sun’s position along the ecliptic in traditional Chinese calendrical science, divide the 12 months into 24 solar terms, each further split into three pentads (侯), totaling 72 pentads.
5天1侯，3侯为一节气，一共72候
For example, in the first lunar month (Yin Month):
The solar term is Beginning of Spring (Lichun), marking the start of spring.
The climatic term is Rain Water (Yushui), occurring when the Sun reaches 330° longitude (between February 18-20 to March 4-5 in the Gregorian calendar).
The phrase “Three Yang Brings Prosperity”(三阳开泰） signifies rising Yang energy, ice melting, and warmer conditions.
The “Nine-Nine Song” and Seasonal Transitions
九九歌
一九二九不出手；三九四九冰上走；五九六九沿河看柳；七九河开八九雁来；九九加一九，耕牛遍地走。
The Nine-Nine Song is a traditional Chinese method to track the seasonal shift after the Winter Solstice:
First & Second Nine: Too cold to take off gloves.
Third & Fourth Nine: Ice is thick enough to walk on.
Fifth & Sixth Nine: Willows sprout along the river.
Seventh Nine: Rivers thaw.
Eighth Nine: Wild geese return.
Ninth Nine plus one more Nine: Farmers begin plowing the fields.
As the seventh nine begins, temperatures rise, and ice starts to melt, symbolizing the transition from winter to spring. This reflects not just astronomical observations but also a deep connection between seasonal changes and cultural traditions.
Rain Water and Seasonal Variations
The Rain Water (Yushui) solar term typically falls in the period from February 18 to March 5. This marks a significant seasonal shift when the warming atmosphere causes ice and snow to melt, increasing moisture in the air. A famous saying, “Spring rain is as precious as oil”, emphasizes the importance of timely rainfall for agriculture, nurturing the awakening earth and encouraging new growth.
However, regional differences shape the experience of Rain Water. In northern China, snowfall may still persist, while in southern China, early spring unfolds with budding greenery, mild sunshine, and warmer days. Southwestern and South regions embrace a vibrant spring, whereas in Yunnan’s southern areas, spring has fully blossomed.
Health and Wellness Aligned with Solar Terms
True health and wellness go beyond diet; they involve aligning with nature’s rhythms. Spring, considered the beginning of the year, corresponds to the Wood element in the Five Elements theory, relates to the Liver, is associated with the color green, and has a taste affinity for sweetness.
During this season, all things grow, including bacteria and viruses, which spread more easily. Therefore, spring is a common period for respiratory illness. One of greatest misconceptions about health is an excessive focus on food and drink, while neglecting the importance of adaptability. The principles of IChing, numerology, imagery, and transformation all point to the need for balance. Change is the most challenging part of life, but learning to listen to one's body and mind allows for effortless harmonization with the rhythms of nature.
Whether through self-adjustment or external assistance—such as breathing exercises or the revitalizing energy of nature—understanding the Yin-Yang calendar leads to a more integrated and holistic approach to life.
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