About The Creator's Calendar

Fact sheet

What is The Creator's Calendar?

The Creator's Calendar is a lunisolar calendar: it draws its months from the natural lunar cycle, and anchors those months within the seasons of the solar year defined by the equinoxes and solstices. It does not sever time from its cosmic phenomena but matches them directly: the day by light, the month by the moon, and the year by the sun.

It thus differs from two common patterns: it is not purely lunar like the Hijri (lunar) calendar (whose months drift across the seasons), nor purely solar like the Gregorian calendar (which disregards the moon); rather it brings both references together, just as the sun and the moon come together in reckoning:

Scientific classification

• Lunisolar: its unit is the true lunar month, and a thirteenth month (Al-Nasi) is added when needed to keep the year in its seasons — of the same type as the Chinese and Hebrew calendars.
• Astronomical, not arithmetical: conjunction, the equinoxes and solstices, dawn and sunset are moments computed from the true positions of the sun and moon, not from averages or fixed cycles. In this it resembles the modern Chinese calendar, and differs from the Hebrew calendar, which rests on the mean “molad” and a fixed 19-year cycle.
• The intercalation rule: close in logic to the Chinese rule (thirteen new moons ⇒ an extra month), but referenced to all four seasons rather than the winter solstice alone; Al-Nasi is inserted into the season in which four moons gather.
• Local reference: anchored to Madinah, just as the Chinese calendar is anchored to the 120° E meridian.
• The day begins at dawn: unlike the common calendars — midnight in the Gregorian, sunset in the Hijri and Hebrew, and sunrise in the Hindu calendars.

The astronomical units and their rules

First: the day begins at dawn

The day is a cosmic unit that begins with the break of true dawn — that is, with the first spread of light on the horizon — not at midnight as convention has it in modern calendars. This is a precise astronomical moment, not an arbitrary one; indeed human life itself begins with the emergence of light.

Second: the month and when it begins

The month is tied to the moon; the new moon is born at the moment of conjunction with the sun, when its light vanishes. But the first day of the month is not counted from the moment of conjunction directly; rather the moon must reach an age sufficient to be seen if sought — a computational criterion that stands in for, and dispenses with, sighting the crescent. The rule:

The moon and the sun together are the instruments of reckoning the Creator appointed for knowing the number of years and months:

Third: the year and the four seasons

The year is solar, and its astronomical bounds are four points that cannot be ignored: the two equinoxes (spring and autumn) and the two solstices (summer and winter), tied to the limits of the sun’s apparent motion between the two principal latitudes (the tropics). As for designating a particular day as the “head of the year,” that is a conventional matter left to peoples and their cultures; the year has no “actual” astronomical beginning, only these four fixed points.

Anchoring the months in their seasons (the linguistic evidence)

The month names themselves carry an explicit seasonal meaning — a linguistic basis showing that each month was tied to its season and did not drift away from it. Lisan al-Arab quotes Ibn Durayd: “When they carried the month names over from the old language, they named them after the times in which they fell.” The witnesses for the order come from Lisan al-Arab itself:

• Rabi al-Awwal and Rabi al-Thani: “The Arabs have two rabi’s: the rabi of water and rain, and the rabi of plants” — the one in which “truffles and blossoms” appear, which is the season that follows winter, i.e. spring; upon them the rest of the months are ordered.
• Jumada: from hardening and dryness, as in the poet’s words “when Jumada withheld its rain” — the month in which the rain stops, which is summer in Arabia.
• Ramadan: from “al-ramad”; and “al-ramadi among clouds and rain is what comes at the end of the hot season and the start of autumn, so called because it meets the heat of the sun” — the first rain on the hot ground in autumn.

Based on these meanings, twelve months are arranged within the four seasons:

The rule for assigning a month to its season

Because the beginning of the “first day” may differ across regions of the earth, a decisive criterion was set for assigning a month to a season: the moon’s age must be two days at the moment the equinox or solstice occurs for that month to be counted within the season. (One day suffices in principle, but “two days” is a safeguard that absorbs the variation in determining the first day between regions of the world.)

Intercalation and Al-Nasi — an astronomical necessity

The solar year is ≈ 365.24 days, whereas twelve lunar months are ≈ 354.37 days, so a difference of about 11 days each year accumulates. Were this difference left unaddressed, the months would gradually drift away from their seasons (as happens in the purely lunar calendar).

When is a year a leap year? And where is Al-Nasi inserted?

• The leap year: the year in which 13 dark moons (new moons) fall — so it needs an extra month.
• The leap month (Al-Nasi): inserted into the season in which four moons of two-days’ age gather, restoring the balance of the months with the seasons.

The arrangement of months in leap years (with the position of Al-Nasi):

The historical origin (year one)

The starting point of the count (year one) is a purely historical matter; here it is a zero point inferred by calibration against the agreement of the events narrated in the sources with it. By this calibration, the first day of the calendar is as follows:

That is, the first year — according to Madinah — corresponds to the year 623 CE.

A calendar that needs no starting point

The Creator's Calendar does not need its first day to be known in order to set its months: it is purely astronomical. Which month we are in is known from the season itself and the moon’s position in it, without reference to previous seasons or years or to the start of the calendar. The month whose moon is two days old at the spring equinox is Rabi al-Awwal wherever it falls in history.

Most calendars, by contrast, can only set their months by a continuous count from their first day. In the Lunar Hijri calendar, for example, there is no way to tell which month we are in by looking at the sky or the season — Ramadan can fall in any season and is known only by counting the months since the calendar began. In the Gregorian calendar, the first of a month is known only by counting the days from the start of the year.

History of the calendar

1. The Creation

   The original order

   “Indeed, the number of months with God is twelve months in the Book of God, on the day He created the heavens and the earth” [At-Tawbah: 36], and “The sun and the moon follow a precise reckoning” [Ar-Rahman: 5]: lunar months within a solar year.
2. 3rd mill. BCE

   The Sumerians

   In Nippur and Ur: lunar months beginning with the crescent, and a month intercalated to keep the year in its seasons — the oldest documented calendars.
3. 3rd mill. BCE

   The Egyptians: the lunar month

   A lunisolar calendar in which the month begins at dawn on the morning when the waning crescent can no longer be seen, with a month intercalated every two or three years to keep the rising of Sirius in place.
4. c. 1780 BCE

   The Babylonian calendar

   Twelve months, the first being Nisannu near the spring equinox, with intercalation by royal decree; and the Babylonian day began at sunrise according to Pliny.
5. c. 499 BCE

   The Babylonian intercalation cycle

   The Babylonians fixed intercalation in a set cycle: seven months in every nineteen years.
6. 6th c. BCE

   The Hebrew calendar

   During the Babylonian exile the Jews adopted the Babylonian month names (Nisan, Iyar…), and they still use their lunisolar calendar (the Hebrew calendar); their day came to begin at sunset.
7. Ancient world

   China, India and Greece

   Lunisolar calendars, all with twelve months and a leap month (the Chinese calendar).
8. Egypt

   The Egyptian civil year

   In it the Egyptians left the moon: 365 days (twelve months and five days), while keeping a lunar calendar for their feasts.
9. 46 BCE

   The Julian, then the Gregorian calendar

   Julius Caesar established a purely solar calendar whose twelve months have nothing to do with the moon; the Gregorian calendar of 1582 came from it (the Gregorian calendar); the Roman day began at midnight, and the modern civil calendar took it from them.
10. Before Islam

    The Arab calendar

    Lunar months kept in their seasons by Al-Nasi.
11. 41 AH

    The purely lunar Hijri calendar

    Intercalation was abandoned, so the Hijri calendar became purely lunar with months drifting across the seasons (the Lunar Hijri calendar), and its day came to begin at sunset.
12. Today

    Reconstruction by astronomical calculation

    The Creator's Calendar is reconstructed on this site and its app from NASA’s ephemeris (JPL DE441) by the rules set out on this page.

Despite everything that befell the calendars, most of the world’s calendars kept the number of twelve months from the original order.

The start of the day through history

The day originally began at dawn, as in fasting: “…until the white thread of dawn becomes distinct to you from the black thread; then complete the fast until the night” [Al-Baqarah: 187], and “nor does the night outrun the day” [Ya-Sin: 40]. Then the nations differed:

In the Lunar Hijri calendar the day came to begin at sunset; al-Maqrizi’s reason is that the month begins with the sighting of the crescent after sunset, so that “for them the night comes before the day.” In the thesis of The Creator's Calendar this was most likely taken from the Jews, and the Prophet’s era followed the dawn. Among its witnesses:

• Standing at Arafa: “The Hajj is Arafa; whoever comes on the night of Jam‘ before dawn breaks has caught it” (Abu Dawud, al-Tirmidhi, al-Nasa’i) — so the day of Arafa extends to the dawn of the Day of Sacrifice, and the night after it is counted with it.
• The Qur’an: “nor does the night outrun the day” [Ya-Sin: 40], and “seven nights and eight days in succession” [Al-Haqqah: 7] — the days exceed the nights by one, so the count begins with a day and ends with a day.
• The counting of hours: in the Futuh al-Sham attributed to al-Waqidi, Abdullah ibn Qurt says: “I rode from Yarmouk on Friday at the tenth hour, after the afternoon prayer… and arrived on Friday at the fifth hour.”

The parts and hours of the day are detailed on the Units of Time page.

The historical evidence: the agreement of events

The central practical argument for The Creator's Calendar is that it is the only calendar with which the events dated in the Arabic sources agree to a high degree.

The clearest witnesses are the weekdays that the sources give for the best-known events of the Prophet's era: they fall exactly in The Creator's Calendar, and not in the Lunar Hijri calendar:

The Evidence of Events page compares the weekday given in the source with the weekday on which the same date falls in each of the two calendars, for every event whose source gives a weekday (exact match · near: one day off · mismatch):

So the calendar the events agree with switches at the handover of rule to Muawiya. Each event can be traced with its historical sources, along with the evidence of the seasons (Badr, Tabuk, the Trench and al-Hudaybiyya), on:

Limits of calculation on this site

• One reference: the starts of the months, years and seasons of The Creator's Calendar are computed for Madinah on every page, not for the user’s city; the times of the day (dawn and sunset) follow the user’s location.
• Dawn: the sun 18° below the horizon; where the night does not reach it (high latitudes in summer), early twilight (−12°), then morning twilight (−6°), then sunrise is used. If none occurs (polar day or night) there is no start of the day, and the civil date is shown.
• Sunset: the disappearance of the sun’s centre with refraction (−0.8333°), the boundary of “day and night” in the rule for the start of the month.
• Range: from year 1 CE to about 3000, by the same rules throughout; dates before the Hijra and after year 41 are computed by the calendar’s rules, not dates people actually used.

Sources and the basis of calculation

Historical sources

• Al-Maghazi — by Muhammad ibn Umar al-Waqidi.
• Tarikh al-Rusul wa al-Muluk (History of the Prophets and Kings) — by Muhammad ibn Jarir al-Tabari.
• Lisan al-Arab — by Ibn Manzur: entries r-b-ʿ, j-m-d, r-m-ḍ (the linguistic evidence).
• Al-Mawaʿiz wa al-Iʿtibar (al-Khitat) — by Taqi al-Din al-Maqrizi: the start of the day among nations.
• Futuh al-Sham — attributed to al-Waqidi.
• Pliny the Elder, Natural History 2.188 — the start of the day among nations.
• Richard A. Parker, The Calendars of Ancient Egypt, University of Chicago Press, 1950.
• Jewish Encyclopedia, “Eve of Holidays” (1906).
• The detailed sources are cited with each event on the Events page.

The basis of astronomical calculation

The moments of conjunction, the equinoxes and solstices, and the times of dawn and sunset are computed from the true positions of the sun and moon in the ephemeris of NASA’s Jet Propulsion Laboratory (JPL DE441). These tables were converted into compact Chebyshev series that the site and the app read directly, matching the Skyfield library within tight limits; all the calculation runs on your device, with no server:

• Conjunction: the moment the apparent longitudes of the moon and the sun are equal.
• Seasons: the moment the sun’s longitude reaches 0°, 90°, 180° and 270°.
• Dawn and sunset: the moment the sun reaches the set altitude at the location.

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