{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"solar-terms"},"result":{"entity_type":"calculator","id":"solar-terms","calculator_id":"solar-terms","canonical_url":"https://tttkmbb.com/lunar/solar-terms","name":"24 Solar Terms Calculator (二十四节气)","title":"24 Solar Terms Calculator – Dates and Times of the Jieqi (节气) for Any Year 1900–2100","category":"lunar","category_name":"Chinese Calendar","tool_name":"list_solar_terms","featured_mcp_tool":false,"description":"Lists the 24 solar terms (节气 jieqi) of a Gregorian year with their exact instants: the moments the Sun's apparent longitude reaches multiples of 15°, computed astronomically and shown in a chosen UTC offset (China Standard Time by default).","use_when":"You need the date or time of 立春, 清明, 夏至, 冬至 or any other solar term in a given year, or the full 24-term table.","do_not_use_when":"You only need the term that a specific date falls in (use lunar-calendar-converter), or you need sunrise/sunset times (use sunrise-sunset).","inputs":[{"name":"year","label":"Gregorian year","type":"integer","required":true,"min":1900,"max":2100,"description":"Gregorian calendar year (1900–2100).","example":2024},{"name":"utc_offset_hours","label":"UTC offset","type":"number","unit":"h","required":false,"default":8,"min":-12,"max":14,"description":"Fixed UTC offset in hours for the local date-times (8 = China Standard Time; 9 = Japan/Korea; 5.5 = India).","example":8}],"outputs":[{"name":"terms","label":"Solar terms","type":"list","decimals":4,"description":"24 rows in calendar order (小寒 first): name_cn, pinyin, english, solar_longitude (°), datetime_local, datetime_utc, date, type (major 中气 / minor 节)."},{"name":"lichun_date","label":"立春 Lichun (Start of Spring)","type":"string","decimals":4,"description":"Local date and time (HH:MM) of 立春, the start of the solar-term year."},{"name":"spring_equinox","label":"春分 Spring Equinox","type":"string","decimals":4,"description":"Local date and time of 春分 (Sun at 0°)."},{"name":"summer_solstice","label":"夏至 Summer Solstice","type":"string","decimals":4,"description":"Local date and time of 夏至 (90°)."},{"name":"autumn_equinox","label":"秋分 Autumn Equinox","type":"string","decimals":4,"description":"Local date and time of 秋分 (180°)."},{"name":"winter_solstice","label":"冬至 Winter Solstice","type":"string","decimals":4,"description":"Local date and time of 冬至 (270°)."},{"name":"year_ganzhi","label":"Year ganzhi (干支)","type":"string","decimals":4,"description":"Sexagenary name of the year with pinyin and element/animal."},{"name":"suishou_note","label":"岁首 (start of the year)","type":"string","decimals":4,"description":"When the sexagenary year begins under solar-term reckoning (立春) versus the lunar calendar (Chinese New Year)."},{"name":"utc_offset","label":"UTC offset used","type":"string","decimals":4,"description":"Offset applied to datetime_local and date."}],"input_schema":{"type":"object","properties":{"year":{"description":"Gregorian calendar year (1900–2100).","type":"integer","minimum":1900,"maximum":2100,"examples":[2024]},"utc_offset_hours":{"description":"Fixed UTC offset in hours for the local date-times (8 = China Standard Time; 9 = Japan/Korea; 5.5 = India). Unit: h.","type":"number","minimum":-12,"maximum":14,"default":8,"examples":[8],"x-unit":"h"}},"additionalProperties":false,"required":["year"]},"output_schema":{"type":"object","properties":{"terms":{"description":"24 rows in calendar order (小寒 first): name_cn, pinyin, english, solar_longitude (°), datetime_local, datetime_utc, date, type (major 中气 / minor 节).","type":"array"},"lichun_date":{"description":"Local date and time (HH:MM) of 立春, the start of the solar-term year.","type":"string"},"spring_equinox":{"description":"Local date and time of 春分 (Sun at 0°).","type":"string"},"summer_solstice":{"description":"Local date and time of 夏至 (90°).","type":"string"},"autumn_equinox":{"description":"Local date and time of 秋分 (180°).","type":"string"},"winter_solstice":{"description":"Local date and time of 冬至 (270°).","type":"string"},"year_ganzhi":{"description":"Sexagenary name of the year with pinyin and element/animal.","type":"string"},"suishou_note":{"description":"When the sexagenary year begins under solar-term reckoning (立春) versus the lunar calendar (Chinese New Year).","type":"string"},"utc_offset":{"description":"Offset applied to datetime_local and date.","type":"string"}}},"formula":"term instant: apparent geocentric solar longitude λ(JDE) = k·15° for k = 0 (春分) … 23 (惊蛰), solved by Newton iteration; UT = TT − ΔT; local time = UT + utc_offset_hours","method":"Solar longitude from the VSOP87 series subset in Meeus (the series also used by the NREL SPA) with nutation and aberration, ΔT from the Espenak–Meeus polynomials; accuracy about ±1 minute (larger far from the present because ΔT is extrapolated), matching the Hong Kong Observatory times to the minute for the checked years. Times are rounded to the minute. Traditional calendar/cultural reference calculation; not a prediction, medical, legal or financial advice.","sources":[{"name":"Solar term (Wikipedia)","url":"https://en.wikipedia.org/wiki/Solar_term","type":"reference","retrieved_at":"2026-09-24"},{"name":"Hong Kong Observatory – Gregorian-Lunar Calendar Conversion Table","url":"https://www.hko.gov.hk/en/gts/time/conversion.htm","type":"government","retrieved_at":"2026-09-24"},{"name":"Meeus J. (1998) Astronomical Algorithms, 2nd ed., Willmann-Bell (solar longitude, nutation, ΔT, new moons)","url":"https://en.wikipedia.org/wiki/Jean_Meeus","type":"textbook","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"2024 (China Standard Time)","inputs":{"year":2024,"utc_offset_hours":8},"expected":{"lichun_date":"2024-02-04 16:27","winter_solstice":"2024-12-21 17:20","summer_solstice":"2024-06-21 04:51","spring_equinox":"2024-03-20 11:06"},"url":"https://tttkmbb.com/api/v1/calculate/solar-terms?year=2024&utc_offset_hours=8"},{"name":"2026 立春","inputs":{"year":2026,"utc_offset_hours":8},"expected":{"lichun_date":"2026-02-04 04:02"},"url":"https://tttkmbb.com/api/v1/calculate/solar-terms?year=2026&utc_offset_hours=8"}],"faq":[{"q":"Why do some sources give a different date for a term?","a":"The date depends on the time zone: a term at 00:30 Beijing time falls on the previous day in UTC. Published Chinese almanacs use UTC+8, which is the default here."},{"q":"What is the difference between 节 and 中气?","a":"The 24 terms alternate: the 12 minor terms (节, odd multiples of 15°: 立春, 惊蛰 …) start the sexagenary months; the 12 major terms (中气, even multiples: 雨水, 春分 …) fix the lunar month numbers and decide which month becomes a leap month."}],"tags":["solar terms","24 solar terms","jieqi","节气","lichun","winter solstice date"],"related":[{"calculator_id":"lunar-calendar-converter","reason":"Which solar-term period a date falls in."},{"calculator_id":"chinese-festivals","reason":"Festival dates, 三伏 and 数九 periods derived from the solstices."},{"calculator_id":"sunrise-sunset","reason":"Sunrise and sunset for the same date and a location."}],"links":{"html":"https://tttkmbb.com/lunar/solar-terms","markdown":"https://tttkmbb.com/lunar/solar-terms.md","json":"https://tttkmbb.com/lunar/solar-terms.json","api":"https://tttkmbb.com/api/v1/calculate/solar-terms","schema":"https://tttkmbb.com/api/v1/calculators/solar-terms","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T08:31:25Z","next_actions":[{"tool":"run_calculator","calculator_id":"solar-terms","reason":"Run 24 Solar Terms Calculator (二十四节气) with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/lunar/solar-terms.md"}}