Equinoxes and Solstices Calculator For Any YearYear Range: 1600 to 2200 Calendar Year(1600  to  2200) Time Zone OffsetNeg | Pos  =  W | E UT Download this PHP 7 Program: 4.1 meg - Equinoxes and Solstices Calculator ========================================================================== EQUINOXES AND SOLSTICES DATES AND TIMES For the Year 2021 =========================================================================== LT (Local Time) in Time Zone UT-05:00 Julian_Date_LT Calendar_Date Time_LT EVENT ---------------- --------------- -------- ----------------- 2459293.69249497 2021 Mar 20 Sat 04:37 AM March Equinox 2459386.43900318 2021 Jun 20 Sun 10:32 PM June Solstice 2459480.09763737 2021 Sep 22 Wed 02:21 PM September Equinox 2459569.95784727 2021 Dec 21 Tue 10:59 AM December Solstice =========================================================================== UT (Universal Time) Julian_Date_UT Calendar_Date Time_UT EVENT ---------------- --------------- -------- ----------------- 2459293.90082830 2021 Mar 20 Sat 09:37 AM March Equinox 2459386.64733651 2021 Jun 21 Mon 03:32 AM June Solstice 2459480.30597071 2021 Sep 22 Wed 07:21 PM September Equinox 2459570.16618060 2021 Dec 21 Tue 03:59 PM December Solstice =========================================================================== TT (Terrestrial Dynamical Time) TT − UT Julian_Date_TT Calendar_Date Time_TT Delta_T EVENT ---------------- --------------- -------- --------- ----------------- 2459293.90162906 2021 Mar 20 Sat 09:38:21 +00:01:09 March Equinox 2459386.64813726 2021 Jun 21 Mon 03:33:19 +00:01:09 June Solstice 2459480.30677143 2021 Sep 22 Wed 19:21:45 +00:01:09 September Equinox 2459570.16698134 2021 Dec 21 Tue 16:00:27 +00:01:09 December Solstice =========================================================================== =========================================================================== SOME GENERAL INFORMATION All computations are based on the NASA/JPL DE405 ephemeris model. The greatest uncertainty is in the future long-term Delta T estimate used to compute the UT and LT (Local Time) of the events. Internally, all core computations are for the TT time scale which is then converted into the corresponding UT and LT. Setting the local time zone offset to ±00:00 equates the local time to UT, which is the same thing. =========================================================================== DEFINITIONS OF THE SEASONS The seasons are being defined geometrically as occurring at 90-degree points in the Earth's orbit. The intervals between them varies, but the angular definitions remain constant. March and September equinoxes = Sun declination 0 degrees June and December solstices = Sun RA at 06 and 18 hours ---------------------- March Equinox Sun on celestial equator crossing from south to north. Beginning of northern spring and southern autumn. On an equinox date, days and nights are closest to equal in length in both hemispheres. This happens twice each year, once in March and again in September, when the sun crosses the celestial equator. ---------------------- June Solstice Sun at RA (Right Ascension) 6 hours (90 degrees). Beginning of northern summer and southern winter. It is the shortest day of the year in the southern hemi- sphere and the longest day of the year in the northern hemisphere. -------------------------- September Equinox Sun on celestial equator crossing from north to south. Beginning of northern autumn and southern spring. On an equinox date, days and nights are closest to equal in length in both hemispheres. This happens twice each year, once in March and again in September, when the sun crosses the celestial equator. -------------------------- December Solstice Sun at RA (Right Ascension) 18 hours (270 degrees). Beginning of northern winter and southern summer. It is the shortest day of the year in the northern hemi- sphere and the longest day of the year in the southern hemisphere. =========================================================== PHP 7 astronomy program by Jay TannerRevised: Thursday, January 01, 1970 at 12:00 AM UTC