Solar-Centric Timekeeping

By+Ji+Jing

The traditional Chinese solar calendar， composed of 24 periods or terms， joined the UNESCOs List of Intangible Cultural Heritage on November 30， 2016.

In tandem with the early development of civilization along the Yellow River in presentday north China， the 24-period calendar and associated social practices arose through observations of both the Suns movement relative to the horizon and of other natural phenomena， especially the weather and the reactions of plants and behavior of animals as the seasons changed throughout the year.

The 24 solar terms embody one complete orbit of the Sun by the Earth， and the dates in the modern Gregorian calendar corresponding to each solar term essentially remain static， differing to minor degrees by just one or two days.

A guide to agriculture

The timekeeping system reflected and guided agricultural activities along the middle and lower reaches of the Yellow River—the political， economic， agricultural and cultural center of ancient China. As the region typically experiences dry weather in spring， two of the seasons solar terms—Rain Water and Grain Rain—were named in accordance with farmers expectations of rain.

During the solar term Lesser Fullness of Grain in early summer， farmers would fortify lakesides and riverbanks to prevent flooding as water levels rose.

From summer to autumn， in the calendar periods Slight Heat， Great Heat and Limit of Heat people would take measures to mitigate the effects of heat and conserve moisture in the fields.

In autumn， when decreasing temperatures could cause agricultural losses， farmers would take preventative action during the solar terms White Dew， Cold Dew and Frosts Descent.

During the six solar periods following autumn—Beginning of Winter， Slight Snow， Great Snow， Winter Solstice， Slight Cold， and Great Cold—as crops had already been harvested and stored， farmers needed only to keep their livestock warm and adequately fed.

“The 24 Solar Terms [calendar] is the most basic knowledge of traditional Chinese agricultural society， which was memorized by every farmer. Its an important component of Chinas farming culture，” said Liu Xiaofeng， a professor of history at Tsinghua University. “The essence of agriculture is to carry out farming activities in accordance with seasonal changes， such as sowing seeds in spring and harvesting crops in autumn. Therefore， being able to predict temperature changes can guarantee a bumper harvest.”

Seasonal festivals

Over the course of history， events celebrated at specific times of year became traditional festivals associated with particular solar terms.

The Beginning of Spring was officially celebrated from the Han Dynasty （202 B.C.-A. D. 220） to the Qing Dynasty （1644-1911）. The authorities would stage grand ceremonies to mark the occasion， and people engaged in various celebratory activities. Villagers would whip paper and earth models of farm cattle， for instance， in the hope of ensuring a good harvest， and Spring rolls were eaten in abundance. The Pure Brightness Festival—also known as Tomb-Sweeping Day in modern times， when people pay respect to their ancestors—similarly became established during the Tang Dynasty（618-907）.

Although the 24-period solar calendar was not adopted in south or west China， whose climates differ markedly from that of north China，people in the south also celebrate festivals such as Pure Brightness and follow the custom of eating rice dumplings during the Winter Solstice.

Modern relevance

The 24 Solar Terms remain relevant even today， as farmers across China still act according to traditional precepts associated with the solar calendar. And， besides their role in guiding agricultural production， the 24 Solar Terms still influence day-to-day life. People in northeast China， for instance， still adhere to the tradition of matching their diet to the prevailing seasonal climate.

Xiang Bosong， a professor at South-Central University for Nationalities in Wuhan， Hubei Province， said almost every solar term has corresponding foods. Adjusting nutritional intake according to the season is beneficial to ones health and represents traditional wisdom about the unity of man with nature， according to Xiang.

“The 24 Solar Terms are not and will not become outdated because they have permeated every aspect of Chinese peoples lives and deeply influence their lifestyles. They show Chinese peoples respect for and compliance with nature and their sustainable development mentality，” said Wang Yingde， a researcher with the China Agricultural Museum.

“The system reminds us that nature changes according to its own rhythm，” Liu said.“The urban culture we have created coexists with nature， and therefore we should learn to respect nature. The solar calendar is valuable for Chinese people because it reflects their ancestors thinking on the relationship between humans and nature.”

In need of protection

Inscription on the UNESCOs List of World Cultural Heritage is a first step in preserving the 24 Solar Terms， but much more needs to be done.

Wang said the Ministry of Culture， Ministry of Agriculture and relevant organizations collaborated in 2014 to form a working group tasked with promoting the traditional calendar. Training sessions will be held to spread knowledge about the 24 Solar Terms， and experts in agriculture， astrology and folklore will be organized to compile related educational material for middle and primary school students. The China Agricultural Museum will stage special exhibitions to raise awareness about the traditional heritage and the need for its protection.

Some customs related to the 24 Solar Terms have disappeared in recent decades， as thousands of villages have been swallowed up by urbanization. In one particular area in Hebei Province， for instance， people still conduct special sacrificial activities in their fields at the Summer Solstice every year. If that village disappears， the custom will also vanish， Liu said.

Protection of such heritage requires taking stock of related customs， formulation of national policies， and efforts by government and non-governmental organizations， according to Liu. He suggested bringing the traditional solar calendar to life by using modern media， such as animations， and more communication channels to promote the traditional timekeeping system among young people.

Xiang said the 24 Solar Terms should also be highlighted on todays calendars， together with associated knowledge and poetry， to familiarize younger generations with the valuable cultural treasure.