Autumn moon viewing, or tsukimi, has long been a popular pastime in Japan. Traditionally it was a way of expressing gratitude for a good harvest and hopes for similar bounty in the future. On the old lunar calendar, the full moon appeared on the fifteenth night (jūgoya) of each month. The best night in the year for observing the celestial body is said to be the fifteenth night of the eighth month of the lunar calendar, known as jūgoya no tsukimi. (In 2018, this is September 24.)
According to traditional reckoning, autumn was from the seventh through the ninth months. The exact midpoint of the season, the fifteenth night of the eighth month, was called chūshū(mid-autumn), so another name for the full moon that night is chūshū no meigetsu (the mid-autumn moon).
The custom of jūgoya moon viewing began in China during the Tang Dynasty (618–907) and spread to Japan thereafter. The aristocrats of the Nara (710–794) and Heian (794–1185) periods enjoyed moon-viewing parties at which they played music and composed poetry. By the Edo period (1603–1868), tsukimi had come to be a popular practice even among commoners, and was closely associated with autumn festival traditions involving thankful offerings of freshly harvested rice to the gods.
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