Niu, the Ox of the Black Tortoise

Niu, the Ox, is the ninth of the twenty-eight xiu and the second mansion of the northern palace, the Black Tortoise. Its name means ox or ox-herd, identified with stars in Capricornus, and it is bound up with the beloved folk tale of the Cowherd and the Weaver Girl, the two lovers set among these stars and the neighbouring mansion. In the later astrological tradition its animal totem is the Ox. As one of the twenty-eight lunar mansions it marks a portion of the Moon's path. These are the conventions of the Chinese astronomical and calendrical tradition, in which the twenty-eight xiu divide the sky into four palaces of seven; the Black Tortoise of the north gathers the mansions the almanac assigns to winter.

The Cowherd and Weaver Girl story anchored at Niu and the following mansion Nu is among the best known folk tales in the Chinese calendar, annually commemorated at the Qixi festival on the seventh day of the seventh lunar month, when the two star-crossed lovers, separated across the Milky Way for the rest of the year, are said to be permitted to meet on a bridge of magpies; the tale gives this pair of otherwise technical lunar-mansion stations a living festival calendar presence that few of the other twenty-eight retain in modern popular practice.