Xiǎomǎn

Xiaoman, Grain Buds, literally Lesser Fullness, is the eighth solar term, at the sun's longitude of 60 degrees, around the twenty-first of May. It is a principal (zhongqi) term. Its name describes the grain in the northern fields growing plump but not yet ripe, filling toward but short of fullness. In the farming almanac it is a time of watchful tending as the crops mature and the summer rains begin, and in the silk regions it is associated with the care of silkworms. Being a solar marker, it falls near the same Gregorian date each year. These are the observances of the East Asian agricultural tradition, resting on the twenty-four-fold division of the tropical year, in which each term names a precise fifteen-degree step of the sun along the ecliptic.

Xiaoman, Grain Buds or Minor Fullness, falls at 60 degrees, around 21 May, and is a qi, or major, term. Its name, literally small fullness, refers to the traditional observation that summer grain crops are filling out but not yet fully ripe at this point in the year, distinguishing it from the fuller, more definite ripeness implied by later terms in the harvest sequence. Xiaoman has no exact counterpart among the twenty-four terms describing an equivalent "minor" stage for the autumn harvest, an asymmetry some scholars attribute to the system's origin as a practical farming calendar focused on the specific rhythms of wheat and early rice cultivation in the North China Plain rather than on a fully symmetrical seasonal design.

The twenty-four solar terms divide the ecliptic into equal arcs of fifteen degrees, and this one falls at 60 degrees of the sun's apparent longitude. It is a major term, a zhongqi, one of the twelve that fall in the even positions of the twenty-four. The major terms are the ones that anchor the lunar months, and they alternate strictly with the sectional terms, so a zhong is always followed by a jie fifteen degrees later.

The terms have not always been spaced the same way. Until the seventeenth century they were reckoned by equal intervals of time, dividing the year into twenty-four equal parts, a method called pingqi. The Shixian calendar, prepared with Jesuit assistance and promulgated in 1645, redefined them by equal intervals of the sun's apparent longitude instead, fifteen degrees apart, which is the definition still used. Because the Earth's orbit is elliptical the sun does not move at a uniform apparent rate, so the intervals between terms now vary by about a day between the shortest and the longest.

Xiaoman, the small fullness, refers to the grain beginning to fill but not yet full, and it pairs with Mangzhong that follows it as one of the sequences of paired terms running through the twenty-four. The pairing convention of a small and a great term recurs four times in the set, in the two heats, the two colds, the two snows and, differently constructed, here, and it gives the list much of its regularity.