1978 carries the identity Wu-Wu in the Chinese sexagenary calendar, the Earth Horse year, its start set by which lunar new year falls inside this Gregorian year rather than by the Gregorian date itself. The system runs two cycles at once: ten heavenly stems, each stem carrying one of five elements across a paired Yang year and Yin year, and twelve earthly branches, each branch carrying one of the familiar zodiac animals. The two cycles advance together, one stem and one branch each year, and because ten and twelve share a lowest common multiple of sixty, the full pairing of stem, branch and element returns only once every sixty years rather than every twelve. This particular pairing, Wu-Wu, last named a year in 1918 and will not do so again until 2038.
The sixty term cycle is older than its zodiac branches alone: it was used to count days as well as years in the earliest Chinese calendars, and its year form still sets the date of the Chinese, Vietnamese and Korean lunar new year, underlies Bazi ("four pillars") fortune telling, which reads a person's stem and branch at birth, month, day and hour together, and paces the lunar timing of some ancestor veneration and temple rites that do not follow the solar calendar. The Gregorian year carried its own religious history quite apart from the sexagenary count: 1978 was the year the Church of Jesus Christ of Latter day Saints extended priesthood ordination to men of all races, and the year Peoples Temple members died at Jonestown in Guyana.