Later, because the lunar calendar date corresponding to the autumn equinox is not fixed every year, and it may not be able to catch up with the full moon, later generations changed the "sacrificial moon festival" to mark the full moon to the 15th day of the eighth month of the lunar calendar, which is today's Mid-Autumn Festival.

A traditional pastime during the autumn equinox sees tens of thousands of people across China doing the vertical egg experiment. It's simple and fun: choose a smooth, well-proportioned egg that's just four or five days old, and gently lift it up into a vertical position on the table.

In Suzhou's Lunan community, Jiangsu province, Yuan Quanmei, a vertical egg maestro, holds an egg and teaches the children to make the egg stand up.

Yuan says it is not easy to keep an egg standing upright, and it even requires a bit of luck, but the key to master the trick is to "choose an egg that is obviously bigger on one end and smaller on the other".