-
Notifications
You must be signed in to change notification settings - Fork 0
Gregorian Comparison
The Light Calendar remains intentionally close to the Gregorian system. It does not seek to replace it wholesale, but to correct specific structural mismatches between civil timekeeping and astronomical reality. The following comparison highlights the relevant differences without proposing a rupture.
The Gregorian calendar uses an average year length of 365.2425 days, a value chosen for long-term civil stability. The Light Calendar instead adopts the mean tropical year, currently 365.2421897 days, derived from the actual motion of the Sun.
The numerical difference is small (about 26–27 seconds per year), but cumulative. Over several millennia, the Gregorian calendar slowly drifts relative to the seasons, whereas the Light Calendar remains aligned by definition. In everyday practice, this distinction is negligible; conceptually, it is foundational.
The Gregorian year begins on 1 January, a historically evolved convention without astronomical significance.
The Light Year begins on 1 New February, defined as the midpoint between the Winter Solstice and the March Equinox, rounded down to midnight UTC. This point marks the transition from decreasing to increasing daylight and serves as a natural anchor for the year.
Gregorian months vary irregularly between 28 and 31 days, a result of layered historical decisions rather than astronomical structure. Their lengths and order carry little seasonal meaning.
The Light Calendar uses twelve Light Months, running from New February to New January. Month lengths are harmonised within a narrow range of 29 to 31 days, with leap adjustment concentrated in New January. This preserves flexibility while maintaining seasonal coherence.
Because the Light Year begins at a fixed astronomical midpoint, the four primary solar events occur consistently near the middle of their respective Light Months. In practice, the solstices and equinoxes fall on day 16 or 17 of those months.
This regularity is a structural consequence of the system, not an imposed rule. The Gregorian calendar also keeps these dates relatively stable, but without internal symmetry or explicit anchoring.
The Gregorian calendar contains no intrinsic lunar structure and requires external lunar calendars for orientation.
The Light Calendar integrates lunar cycles directly through a continuous lunar index (M1–M13, with optional boundary markers). Each lunar cycle belongs to the year in which its full moon occurs, maintaining continuity across year boundaries without introducing a separate calendar layer.
Because the Light Year is aligned to an astronomical midpoint rather than fixed civil dates, the two systems do not remain in constant phase. The offset typically ranges from two to three days near the start and end of the year, increasing to five or six days around mid-year. This variation is expected and reflects the differing reference principles.
The Light Calendar improves seasonal coherence, month structure, and lunar integration while remaining close enough to the Gregorian system to allow parallel use. It is not intended as a disruptive replacement, but as a structurally clearer alternative grounded in astronomical reality.