"Zhong Qiu Jie" (Mid-Autumn Festival), is celebrated on the 15th day of the 8th month of the lunar calendar, when the moon is supposedly at its fullest and roundest.
It is a time for family members to congregate, admire the full moon and eat mooncakes. The full moon is a symbol of reunion.
"Zhong Qiu Jie" probably began as a harvest festival. But later it’s more famous for the legends of a beautiful lady, Change'e.
According to Chinese folktale, the earth once had 10 suns circling over it, and each takes turns to illuminate the world. One day, all 10 suns appeared together, scorching the earth with their heat. An expert archer, Houyi, stepped forward and succeeded in shooting down 9 of the suns.
Houyi got elixir from a goddess, which was later stolen by his wife, Chang'e. After swallowing the elixir, Chang'e found herself floating to the sky because of the overdose, grabbing a rabbit to keep her company. She finally landed on the moon, immortal, but separated from her husband forever.
So we say that if you look up at the moon on this day, you can sometimes see a rabbit making elixir.