In which year was Tomb-Sweeping Day on April 4th?

1992, 1996, 2000, 2004, 2008, 2009, 20 12, 20 13, 20 16 and 20/kloc-0.

Because Qingming is based on the relative position of the sun and the earth to determine the date, when the sun reaches longitude 15 degrees, it is Tomb-Sweeping Day. And the earth's rotation around the sun is not an integer of 365 days. The rotation of the earth around the sun is 365 days, 5 hours, 48 minutes and 46 seconds, so every four years or so, there will be a day difference.

The traditional solar terms in China are calculated according to the annual vernal equinox, which has a solar term every 15 days, so Qingming is mostly between April 4 and 6 in the solar calendar. It is not fixed on April 5 of the solar calendar, nor is it determined by the lunar calendar. The vernal equinox changes with the rotation of the earth. The earth's daily rotation is not 24 hours, but 23 hours and 56 minutes, which will be reduced by one day every four years, thus affecting the time of solar terms. According to this rule, April 4th happened in Tomb-Sweeping Day in 2008 and 2009.

Origin of the festival

Tomb-Sweeping Day has both natural and humanistic connotations. It is not only one of the 24 solar terms, but also a traditional festival for ancestor worship. Twenty-four solar terms are the product of ancient farming civilization, which is related to the time of gossip and has a long history. Twenty-four solar terms not only play a guiding role in agricultural production, but also affect the food, clothing, housing and transportation of ancient people, and even cultural concepts.

In the early days of observing images and timing, bucket handle made a clockwise rotation according to the movement of stars, which was called one year old. Tian Yuan began in Yin, such as "Astronomical Training of Huainanzi", which includes: Emperor, Yun Dou, moving to the ground for one day, returning to the ground in the first month, referring to Yin in the first month, ugly in December, and turning at the age of one.