Lìchūn

Lichun, the Start of Spring, opens the cycle of twenty-four solar terms at the sun's celestial longitude of 315 degrees, around the fourth of February. It is a sectional (jie) term and traditionally the first term of the year, marking the point where winter yields to the earliest stirrings of spring. In the agricultural almanac it is the signal to prepare the fields and tools for the coming season, and it has long carried its own customs, the ceremonial welcoming of spring, the eating of spring pancakes, and the fashioning of a clay ox to encourage the plough. Because the solar terms track the sun rather than the moon, Lichun falls on nearly the same Gregorian date each year. These are the observances of the East Asian agricultural tradition, resting on the astronomical division of the tropical year into twenty-four equal solar arcs.

The twenty-four solar terms as a whole were inscribed on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity in 2016, recognising the system as a living body of agricultural and folk knowledge rather than only a technical astronomical scheme. Each term is traditionally further divided into three five-day hou, or pentads, giving seventy-two shorter divisions across the year, each historically assigned a description of a natural sign, an animal's behaviour, a plant's budding, drawn from texts such as the Yueling, the Monthly Ordinances chapter of the classical Book of Rites.

The twenty-four solar terms divide the ecliptic into equal arcs of fifteen degrees, and this one falls at 315 degrees of the sun's apparent longitude. It is a sectional term, a jie, one of the twelve that fall in the odd positions of the twenty-four and open the twelve solar months. The sectional terms and the major terms alternate strictly around the year, so a jie is always followed by a zhong fifteen degrees later.

The twelve major terms are what make the Chinese calendar work as a lunisolar one. Each ordinary lunar month is expected to contain exactly one major term, and the month takes its number from the term it contains, so the eleventh month is by definition the one holding the winter solstice. When a lunar month falls entirely between two major terms and contains none, it is declared intercalary and repeats the number of the month before it, which is how a thirteenth month is inserted without any fixed rule about when.

Lichun carries a weight the other sectional terms do not, because it, and not the lunar New Year, begins the year in the sexagenary reckoning used for fate calculation. A Four Pillars chart takes its year pillar from Lichun onward, so a birth in late January or early February can fall in one animal year by the festival calendar and the previous one by the astrological reckoning. Popular custom also treats a lunar year containing no Lichun as inauspicious for weddings, a belief that follows from the intercalation rule rather than from anything about the term itself.