Mid-autumn Day is August 15th on lunar calendar. According to history records, Chinese emperor has tradition that worship the Sun in spring and worship the Moon in autumn. As august 15th is exactly the middle of autumn, so it is called Mid-Autumn Day.
The traditional food of Mid-Autumn Day is Moon cake, a round baked cake with fillings in it. The round shape of moon cake represents family together. In the night of Mid-Autumn Day, every family has moon cake and watches the moon.