Summer solstice is the origin of summer solstice.

The summer solstice is in May or June of the lunar calendar every year (June 20th or 2 1 day of Gregorian calendar), when the sun runs to 90 degrees of the Yellow Meridian, which is also the longest day and the shortest night in a year.

The summer solstice originated from the ancient people's observation and recording of the sun's orbit. In ancient China, the summer solstice was one of the important solar terms, and it was also a traditional agricultural festival in China. Summer solstice is a key period for crop growth, because it marks that the days are getting shorter and the nights are getting longer. Farmers need to adjust their farming activities such as planting and harvesting according to this solar term. In ancient times, the summer solstice was also an important day to worship the sun god.

Besides China, the summer solstice is also an important festival for many cultures and religions in the world. For example, in the Nordic countries, people celebrate the summer solstice festival, also known as the "midsummer festival". On this day, people will hold celebrations, such as bonfire parties and dancing.