The four instants each year when the seasons turn: the Sun’s apparent longitude crosses 0°, 90°, 180° and 270°, and astronomical spring, summer, autumn and winter begin — on opposite calendars in the two hemispheres. Published minutes, 2015–2040.
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Day and night are nearly equal again — astronomical autumn begins in the north, spring in the south.
spring begins in the north · autumn in the south
20 March 2027, 20:25 UTC
Day and night are nearly equal everywhere — astronomical spring begins in the north, autumn in the south.
summer begins in the north · winter in the south
21 June 2027, 14:11 UTC
The Sun stands farthest north — the longest day of the year in the northern hemisphere, the shortest in the south.
autumn begins in the north · spring in the south
23 September 2026, 00:05 UTC
Day and night are nearly equal again — astronomical autumn begins in the north, spring in the south.
winter begins in the north · summer in the south
21 December 2026, 20:50 UTC
The Sun stands farthest south — the shortest day of the year in the northern hemisphere, the longest in the south.
| Event | Date | Time (UTC) |
|---|---|---|
| March Equinox | 20 March | 14:46 |
| June Solstice | 21 June | 08:24 |
| September Equinox | 23 September | 00:05 |
| December Solstice | 21 December | 20:50 |
Earth’s distance from the Sun is not what makes summer: in 2026 we were actually closest to the Sun (perihelion) on 3 January 2026, 17:15 UTC — northern midwinter — and farthest (aphelion) on 6 July 2026, 17:30 UTC, in northern midsummer. The seasons come from Earth’s 23.4° axial tilt, not the ~3% swing in distance. Instants: USNO, Astronomical Applications Department.
The minutes on this page are the published instants of the USNO, Astronomical Applications Department (UT, minute precision), frozen 2026-07-17 for 2015–2040. LEV also computes every instant independently (Meeus’s standard algorithm); across all 104 published events the two agree within ±91 seconds — the computation cross-checks the table and drives the countdown, and never replaces a published minute. Four 2026 instants were additionally verified against JPL Horizons (DE441) to within ~31 s. One honest caveat: beyond the early 2030s, everyalmanac’s minute — this one included — depends on predictions of Earth’s slightly irregular rotation (ΔT), and can shift by up to about a minute as those predictions meet reality.