Dongzhi, the Winter Solstice, is the twenty-second solar term, at the sun's longitude of 270 degrees, around the twenty-second of December. It is a principal (zhongqi) term and the shortest day of the year in the northern hemisphere, when yin reaches its extreme and, in Chinese cosmology, yang begins its return, the turning point from which the light grows again. It is among the most important of the terms as a festival: families gather, and in the north dumplings and in the south glutinous rice balls are eaten to mark the day, an occasion sometimes ranked with the new year. Being anchored to the solstice itself, it falls near the same Gregorian date each year. These are the observances of a living East Asian tradition, resting on the solar-term division of the tropical year.
Dongzhi, the Winter Solstice, falls at 270 degrees of ecliptic longitude, the sun's most southerly point relative to the celestial equator, around 21 or 22 December, and is a qi, or major, term, the shortest day and longest night of the year in the Northern Hemisphere and, like Xiazhi, one of the four cardinal terms fixed by direct astronomical observation using a gnomon well before the full twenty-four-term system was completed. Dongzhi has historically been treated in China as a major festival in its own right, in some periods and regions rivalling the Lunar New Year in importance, marked by family reunion meals, the eating of dumplings in the north and of glutinous rice balls, tangyuan, in the south, customs that persist widely today.