Why does February have 28 days?
Because a Roman emperor removed two days from it.
The Gregorian calendar is not mathematics. It is politics — layer upon layer of imperial decisions, religious compromises, and administrative convenience, accumulated over two thousand years. The Terran Calendar starts from scratch.
The mathematics ↓13 × 28 = 364
Every month identical. No month longer or shorter than another. No exceptions.
Exactly 4 weeks. Every month begins on the same day of the week. Every week is complete.
13 × 28 = 364 = 52 × 7. Zero remainder. No partial weeks. No drift.
The solar year is approximately 365.25 days. 364 days leaves one day — or two in a leap year — unaccounted for. These are Foundation Day (day 29 of Zola) and Leap Day (day 30 in leap years) — held within Zola, the planetary month shared by both hemispheres beginning September 16. In the NH, they sit at the midpoint of the year — between Daichi (month 6) and Tecido (month 8). In the SH, they sit at the year's end — between Chuánchéng (month 12) and the new year beginning October 15. They belong to neither month nor week. They are the planetary pause — shared simultaneously by both hemispheres.
Zola is Earth's birthday. Ophiuchus ⛎ is its sign.
The Gregorian calendar has twelve months of wildly inconsistent length. No month begins on the same weekday twice. No quarter has the same number of days.
* 28 days — or 29 in a leap year · Months range from 28 to 31 days · No mathematical justification
The Terran Calendar has thirteen months of exactly 28 days, plus Foundation Day (and Leap Day in leap years) within Zola.
Every month: 28 days · 4 weeks · Foundation Day / Leap Day: intercalary days within Zola · Named from six language families
The Gregorian calendar begins January 1 — a date with no astronomical meaning whatsoever.
The Terran Calendar begins at the March equinox —
the moment the sun crosses the celestial equator heading north.
It occurs every year with absolute precision.
It is the same event for both hemispheres simultaneously.
It is a physical absolute, not an administrative choice.
From the equinox, the NH new year begins April 1
— the first full day of the new arc, after the equinox threshold.
The SH new year begins October 15
— exactly six Terran months (168 days) later, when the Southern Hemisphere enters its equivalent opening. Both hemispheres enter Zola on the same day: September 16.
Spring opens · Acerto begins · Dissolution · "What are we actually made of?"
Southern spring opens · Acerto begins · Dissolution · "What are we actually made of?"
Both hemispheres share the same thirteen months, the same names, the same structure. What differs is where in the year arc each month falls — and what the season means when you are standing in it.
Thirteen months. Twenty-eight days. Zero remainder.
Document III contains the full mathematical and philosophical case — the history of the Gregorian calendar, the complete structure of the Terran Calendar, the Foundation Day / Leap Day intercalary system, and the hemispheric anchor.
Document III · Free · Open access · CC BY 4.0 · Permanent DOI