For thousands of years, farmers have used the Chinese calendar to figure out the best times to plant and harvest crops.
In China, asking for someone’s birth date can yield confusing answers, especially among the older generation.
That’s because many people have two birth dates: one according to the Gregorian calendar and one according to the traditional Chinese calendar.
Unlike the Gregorian calendar, which is used in most parts of the world, the Chinese calendar bases its dates off the moon’s movement around the Earth, combined with the Earth’s movement around the sun. The Gregorian calendar only tracks the Earth’s orbit.
One month in the Chinese calendar is the length of time between two new moons, roughly 29.5 days.
For generations, farmers have used this calendar to predict natural phenomena and figure out the best times to plant and harvest crops, which is why some people consider it the world’s oldest almanac.
Records of the calendar date back to the Zhou Dynasty (1046-256 BC). A year is divided into 24 solar terms based on the Earth’s movement around the sun.
These solar terms each have a label denoting a different natural phenomenon. For example, the solar term jingzhe 惊蛰, which means “waking of the insects,” usually occurs around March.
That refers to the first rainstorm that kicks off spring by waking up hibernating insects. It’s said to be a good time to plant seeds.
Nowadays, most of the population in China uses the Gregorian calendar, in line with the rest of the world, but there are still some people, especially farmers and older generations, who consult the Chinese calendar.
And it’s not just for agricultural advice. Modern Chinese calendar designs also include predictions, horoscopes, lottery numbers, and even recipes of the day.
“There’s all sorts of weird stuff,” says Leung Yu-tim, owner of a calendar publisher in Hong Kong.
Every year, his company hires a feng shui consultant to write the calendar’s contents.
Particularly superstitious folks might use it to find the most auspicious dates for important events such as weddings, moving into a new house, and starting a business.
But the calendar’s most important use is observing traditional holidays such as Chinese New Year and the Mid-Autumn Festival, which are celebrated by the Chinese diaspora around the world.