Light Calendar 2025/26 •

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The year 2025/26 runs from 03.02.2025 to 03.02.2026 and has the following astro­nomical fixed points: 17th New March (VE), 17th New June (SS), 17th New Septe (AE), 17th New Dece (WS) – explanation below, V1.2.4

< 2024/25 | 2025/26 | 2026/27 >

< 2024/25 | 2025/26 | 2026/27 >

Explanation:
The Light Calendar divides the year into 4 almost equal quarters, each centered exactly midway between the astronomical fixed points (winter solstice, vernal equinox, summer solstice, autumnal equinox). This creates 4 seasons with distinct character: Early Spring (days rapidly get brighter each day/ΝFeb-ΝApr, warmth arrives delayed), Early Summer (time of long days/ΝMay-ΝJul), Early Autumn (days rapidly get shorter each day/ΝAug-ΝOct), Early Winter (dark season with little daylight change/ΝNov-ΝJan).

Every year begins with 1st New Febr (start of Early Spring). The leap month is New Jan; in leap years it has one extra day (marked ¹). Leap years are shifted ca. two years compared to the Gregorian calendar. For practical reasons the year number still changes on 1st Jan as usual. The lunations of a light year are numbered 1-13 (similar to week numbers). A lunation belongs to a light year if its full moon occurs within that year. The cycle begins with the astronomical new moon: if this occurs before 12:00, the previous day/night counts as the beginning; after 12:00, the same day counts as the beginning.

This PHP version does NOT compute full astronomical precision (unlike the app), but provides a good approximation of all dates, seasons, and moon cycles. All times shown in Central European Time (UTC+1|2).

Lunations of light year 2025/26:
1. Moon – new: Wed, 29.01.25, full: Wed, 12.02.25
2. Moon – new: Thu, 27.02.25, full: Thu, 13.03.25
3. Moon – new: Fri, 28.03.25, full: Sat, 12.04.25
4. Moon – new: Sun, 27.04.25, full: Mon, 12.05.25
5. Moon – new: Mon, 26.05.25, full: Tue, 10.06.25
6. Moon – new: Tue, 24.06.25, full: Thu, 10.07.25
7. Moon – new: Thu, 24.07.25, full: Fri, 08.08.25
8. Moon – new: Fri, 22.08.25, full: Sun, 07.09.25
9. Moon – new: Sun, 21.09.25, full: Mon, 06.10.25
10. Moon – new: Tue, 21.10.25, full: Wed, 05.11.25
11. Moon – new: Wed, 19.11.25, full: Thu, 04.12.25
12. Moon – new: Fri, 19.12.25, full: Fri, 02.01.26
13. Moon – new: Sun, 18.01.26, full: Sun, 01.02.26

The moon display (see above) works as follows: Μx·y(p/z) = x. Moon, y. Day, p=full moon day, z=cycle length.

In the same vein is 'Gordon's Sun Clock', a single-hand clock whose dial changes daily with the seasons. It is available as a free Android app:

Gordon’s Sun Clock >
Info about Light Calendar (Github) >

For more precise calculations, please check the Android app or the web app.