二十四節氣（24 solar terms），是指太陽曆（幹支曆）中表示季節變遷的24個特定節令，是根據地球在黃道（即地球繞太陽公轉的軌道）上的位置變化而制定的，每一個分別相應于地球在黃道上每運動15°所到達的一定位置。二十四節氣是上古時代通過觀察太陽周年運動，認知一年中時令、氣候、物候等方面變化規律所形成的知識體系。它把太陽周年運動軌迹劃分爲24等份，每一等份爲一個節氣，始于立春，終于大寒，周而複始。
二十四節氣，是古人依據黃道面劃分制定，屬太陽曆範疇，上古時代已訂立，到漢代吸收入《太初曆》作爲指導農事的補充曆法。二十四節氣既是曆代官府頒布的時間准繩，也是指導農業生産的指南針，日常生活中人們預知冷暖雪雨的指南針，是中華民族勞動人民長期經驗的積累成果和智慧的結晶。
二十四節氣，是古人依據黃道面劃分制定，屬太陽曆範疇，上古時代已訂立，到漢代吸收入《太初曆》作爲指導農事的補充曆法。二十四節氣既是曆代官府頒布的時間准繩，也是指導農業生産的指南針，日常生活中人們預知冷暖雪雨的指南針，是中華民族勞動人民長期經驗的積累成果和智慧的結晶。
A solar term is any of 24 points in traditional East Asian lunisolar calendars that matches a particular astronomical event or signifies some natural phenomenon.The points are spaced 15° apart along the ecliptic and are used by lunisolar calendars to stay synchronized with the seasons, which is crucial for agrarian societies. The solar terms are also used to calculate intercalary months in East Asian calendars; which month is repeated depends on the position of the sun at the time.
Because the Sun's speed along the ecliptic varies depending on the Earth-Sun distance, the number of days that it takes the Sun to travel between each pair of solar terms varies slightly throughout the year. Each solar term is divided into three pentads, so there are 72 pentads in a year. Each pentad consists of five, rarely six, days, and are mostly named after phenological (biological or botanical) phenomena corresponding to the pentad.
On December 1, 2016, 24 Solar Terms were listed as UNESCO's Intangible Cultural Heritage.
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