The origin of perpetual calendar?

The origin story of perpetual calendar:

Legend has it that a long time ago, a young man named Wannian saw that the festivals at that time were chaotic and wanted to arrange them in a unified way. One day, he went up the mountain to collect firewood. When he was tired and sat in the shade to rest, the movement of the shadows inspired him. So he designed a coffin to measure the shadow of the sun and record the date.

But the disadvantage is that rainy and foggy weather will affect the measurement. Later, the dripping spring water on the cliff aroused his interest, and he made a five-story clepsydra. As time went on, he found that the length of a day would be repeated every 360 days.

At that time, the emperor's name was Zu Ti, and he was moved and distressed by the sudden weather. Ten thousand years later, he took the sundial and the clepsydra to the emperor to explain the principle of the sun and the moon.

Zuyi thinks it makes sense. So he stayed for ten thousand years, built a sundial table and a leaky pot pavilion in front of the Temple of Heaven, and sent 12 boys away in ten thousand years. Zu Ti said to Wannian: "I hope you can calculate the laws of the sun and the moon, calculate the exact time in the morning and evening, and create a calendar for the people all over the world."

Day after day, year after year. After long-term observation and careful calculation, an accurate solar calendar was finally worked out after 10 thousand years. When he presented the solar calendar to the successor monarch, he was already full of silver hair. The emperor was deeply moved. In order to commemorate the achievements of 10 thousand years, he named the solar calendar "perpetual calendar" and named it the birthday star of the sun, moon and moon.

Extended data:

Composition of perpetual calendar:

In the past, the perpetual calendar recorded the dates of the solar calendar and the lunar calendar within a certain time range;

The perpetual calendars in use now include calendars suitable for several years, solar calendars, lunar calendars, dry calendars and other calendars, as well as various functional information related to the yellow calendar, such as good or bad luck, holiday reminders and so on.

It should be noted that 10,000 years is only a symbolic meaning, which is used to indicate a large time span. ?

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