According to a famous Chinese legend, the sky was originally lit by ten suns, whose combined heat scorched the earth and crops so that the people had nothing to eat. To save the world from imminent starvation China's most famous archer, Hou Yi, shot down nine of the suns with his bow and then rid the land of poisonous snakes and beasts so people could live in peace and happiness.

Unfortunately for Hou Yi, these ten suns turned out to be the sons of the Jade Emperor, who was so angered by the loss of his sons, that he banished the archer together with his wife, Chang O, and children from the face of the earth. When the Western Goddess discovered what had happened, she took pity on Hou Yi, giving him an elixir of immortality. But Chang O greedily swallowed the potion by herself and as the concoction worked through her body she became lighter and lighter and floated up into the sky. Fearing that the deities in heaven would laugh at her, she took refuge on the moon, building there a palace known as the "Cold Palace," where she lives to this very day as the Lady of the Moon. Since it is believed that Chang O floated to the moon on the fifteenth day of the eighth moon, people offer annual prayer and sacrifices to the moon on that day to commemorate the event.

It is said that Chang O transforms herself into brilliant moonlight and descends to earth to offer good fortune. Thus, couples to swear their mutual love under the full moon and separated lovers to pray to the for reunion under the full moon.

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