Solving the mystery of the ancient 360-day calendar


It appears that ancient 360-day calendars may have been used globally until about the eighth century BCE., a leading internet source, has cataloged evidence of eleven different cultures that may have used 360-day calendars at one time or another.

This article is an investigation into the possible source and purpose of such a calendar.

The question that first pops in one’s mind is; how is it possible that eleven widely separated cultures came up with identical calendar systems?  The physical barriers such as mountains, deserts, and oceans separating Mesopotamia, Mesoamerica and China would seem to preclude the merging of proprietary technologies. So, what happened?

It also seems unlikely that the 360-day calendar has anything to do with tracking seasons as it would have become out of sync by a full month in just 5-years. As a result, it would have been discarded. But the calendars were not discarded. In fact, they were widely used for a period of at least two-thousand years. That would suggest that the 360-day calendar was crafted to serve another purpose.

At least in some cases, such as with the Mayans and Egyptians, the 360-day calendars were an integral part of 365-day calendar systems. Intercalary periods were used for synchronization of the calendars over longer periods of time.

According to the Ancient History Encyclopedia the ancient Sumerians emerged as a culture around 5,000 BCE and lasted until about 1,750 BCE. Historically, what we call civilization, likely began in the ancient city of Eridu. As the oldest known civilization, it seemed reasonable to assume they were the first culture to embrace a 360-day calendar and so, they became the initial focus of this investigation.

The literature explained how their history and accomplishments had been lost in time–even their name. Their secrets remained buried in the deserts of Iraq until the 19th century AD when French and British archaeologists finally stumbled upon Sumerian artifacts while hunting for evidence of the ancient Assyrians. Since then, archaeologists have recovered some 500,000 clay tablets, the majority of which are yet to be translated.


By 3,100 BC the Sumerians had already become a highly advanced and sophisticated civilization. They had a writing system (cuneiform script) and a library containing hundreds of thousands of historical documents. They also had a highly functional governmental structure and legal system and were building bridges, dams, aqueducts and irrigation systems. Mathematically, it appears that their skills were well beyond what historians had imagined. The evidence suggests that they could perform advanced arithmetic calculations and may have been the initiators of the science that would later become known as astronomy. They brought us the Sexagesimal structure for measuring time–using seconds, minutes and hours as well as our system of measure–based on miles, feet and inches. They had mastered geometry and were able to calculate areas of rectangles, triangles, and trapezoids and said to have used sophisticated geometrical calculations for tracking the movement of planets.

Unraveling the mystery

After working on the puzzle off and on for several years an original concept slowly began to evolve.

I learned that the Sumerians divided the 360-day year into 30-day months, the day into twelve 2-hour periods, and the 2-hour periods into thirty 4-minute intervals. With 1440-minutes in a day, 4-minutes is equivalent to 1/360th of a day. That piece of information told me that the Sumerians not only divided the Earth’s orbit into intervals of 360, they also divided Earth’s rotation into intervals of 360.

That lead to the discovery of what I now refer to as the “Sacred Cube”.

4-minutes X 360 = 1440-minutes (the measure of a day)
1440-minutes X 360 = 518,400 (the measure of a year)
518,400-minutes X 360 = 186,624,000 miles (the measure of distance)

 When 4-minutes is multiplied by 360 it results in 1440-minutes or 1-day. When those 1440-minutes are multiplied by 360-days it results in 518,400-minutes or one 360-day year. When 518,400-minutes are multiplied by 360 the result is 186,624,000 miles. Curiously, that number matches a value listed in the Cannon of ancient numbers which are defined as the Earth’s orbital diameter (93,312,000 X 2 = 186,624,000). More precisely, this figure is the line of apsides.

Being a bit uneasy about the implications of this, I decided to let the matter set.

A couple of years later I was trying to make sense out of the Sexagesimal system and came up with an idea. I decided to deconstruct the 186,624,000 number that I had previously came up with using the Sexagesimal time structure of a day. First, I divided 186,624,000-miles by 360-days which resulted in 518,400-miles per-day. That figure was then divided by 24-hours which resulted in 21,600-miles-per-hour. Next, 21,600-miles was divided by 60-minutes which resulted in 360-miles per-minute. Finally, the 360-miles per-minute was divided by 60-seconds which resulted in 6-miles per-second or 6-hertz–the very same frequency insisted on by the great Nicola Tesla.


To summarize what I’d learned up to that point;

  1. The cube of 360 X 4 equals 186,624,000-miles (theoretical diameter of Earth’s orbit).
  2. 186,624,000-miles is the product of a Sexagesimal year.

At this point and time, I was convinced that the Sumerians were the legitimate source of the 360-day calendar. But I was troubled by the size of the discrepancy between 186,624,000-miles, the proposed diameter of Earth’s orbit, and the currently accepted value. So, once again I decided to let the matter set.

Several years later I came across a paper written by researcher Arnold D. Enge. He had discovered that the ancient Mayan used 365.625 days when calculating the Earth’s orbit instead of our 365.242-day tropical year. The Mayan name for the 365.625-day period is “uinalhaab” which means one-year. The “uinalhaab” turned out to be the missing piece of my puzzle.

Here are the numbers in table format:

Sol-Lunar Year

A lunar-year of 354.375-days is consistent with the present-day Islamic calendar which has been in use since ancient times. The 365.625-day “uinalhaab” has now been verified by other qualified authorities. The average of those two periods is precisely 360-days.

At that point, I supposed that ancient astronomers had, somehow, developed a calendar to track the apsidal motion of an Earth-Moon binary system.


To verify that supposition I decided to utilize the time-distance formula that I had learned earlier (4-minutes X 360 X 360 = 518,400). But, instead of multiplying 518,400 by 360 as I had done earlier, I multiplied that figure instead by the number of days in the lunar year and the number of days in the uinalhaab (see below).

The table shows that the orbit’s closest approach to the Sun (perihelion) is 91,854,000 miles and that the farthest approach (aphelion) is 94,770,000-miles. The sum of those two (186,624,000-miles) forms the line of apsides. The preciseness of the calculation was enough to convince me that the 360-day calendar was defined by an Earth-Moon binary system (see below).

The above illustration depicts the orbit of the Earth-Moon system as an ellipse instead of a circle. The important difference between circular orbits and elliptic orbits is the construction of their orbital diameters. When circular orbits are divided by Pi the result is the length of their orbital diameter (which is precisely two times its radius). With an ellipse, however, the orbital diameter is replaced with the “line of apsides”.

The line of apsides is composed of two axes of differing lengths. One axis is the distance from the center of rotation to the orbit’s aphelion and the other axes are the distance from the center of rotation to the orbit’s parhelion. According to Newton, those two components cause two opposing fields or waves to be created (see below).

Apsidal Motion


The variance in length of the two axes is what defines the synodic period (the number of rotations necessary to evenly distribute the variance and return to the point of equilibrium). Newton’s theorem of revolving orbits describes this phenomenon as apsidal or orbital precession.

The formula for calculating the apsidal precession period is as follows:

The number of days shown in red in the formula below is taken from the table above identified as the “Apsidal Precession Component Profile”.

[-360 / ((360/182.8125 days) – (360/177.1875 days)) = 5758.59375 days]

What the formula tells us is that it takes 5758.59375 days for the Earth-Moon system to evenly distribute the variance in length of the perihelion and aphelion axes and return to a point of orbital equilibrium–a period of almost exactly 16 solunar years.

Further Synodic implications

Interestingly, the synodic components from which the 360-day period is formed are periods that the ancients defined as months.

[-360 / ((360/30-days) – (360/27.69230769-days)) = 360-days]

The formula tells us that 360-days is comprised of twelve 30-day periods and thirteen 27.69230769-day periods. The mean is 28.8-days (see table).


The following diagram shows an outer orbital perimeter in red resulting from 365.625 X 518,400 and an inner orbital perimeter in blue resulting from 354.375 X 518,400. The mean solunar orbit of 360-days is white in color. The white dotted line illustrates the lunar motion that produces the 27.69230769-day oscillations.



The implication of all of this is considerable 

For example, 27.6923076923 X 260 = 7,200-days or 20 solunar years (Mayan Katun) and 30 X 360 = 10,800-days or 30-solunar years (Saturn orbital period).

The Katun (consisting of 7,200-days) is based on the synodic relationship between the mean orbit period of Saturn (10,800-days) and the theoretical mean rotation period of the solar system’s center of mass (4,320-days) which is very closely associated with the orbit of planet Jupiter (see below).

Synodic [-360 / ((360/10,800 days) – (360/4320 days)) = 7200 days]

The Katun is also closely linked to Jupiter’s relationship with the Earth-Moon system. The Earth-Moon system’s synodic period with Jupiter is about 400-days. When those 400-days are inserted into the formula below the Katun pops up.

Synodic [-360 / ((360/400 days) – (360/360 days)) = 3600 days X 2 = 7,200-days]

Another extremely important implication is the synodic relationship between the 354.375-day period and 365.625-day period:

Synodic [-360 / ((360/365.625 days) – (360/354.375 days)) = 3,986.71875 days]

Why this calculation is so important is because 3,986.71875 divided by 360-days turns out to be 11.07421875-years (the mean length of the sunspot cycle).

Further implications

When the synodic period between 365.625-days and 360-days is calculated, the result is as follows:

 Synodic [-360 / ((360/365.625 days) – (360/360 days)) = 23,400 days]

Now, by dividing 23,400 by 360-days we come up with 65-solunar years


Why is 23,400-days or 65 solunar years important?

Simply put, it is the grand synodic period of the inner solar system:

  • Earth-Mars synodic period is 780-days X 30 = 23,400
  • Earth-Venus synodic period is 585-days X 40 = 23,400
  • Uinalhaab orbital: 365.625-days X 364 = 23,400
  • Solunar orbital: 360 X 65-days = 23,400
  • Lunar orbital: 354.5454: 66 X 360 = 23,400
  • Venus orbital: 225 X 104 = 23,400
  • Mercury orbital: 87.96992481 X 266 = 23,400

All the above orbitals divide evenly into the grand synodic period (no remainders). This implies that all inner planets are in perfect harmonic resonance with a cycle of 23,400-days.

Harmonic resonance is simply natures method of propagating energy

This concludes this post. Thank you for taking the time to read it.


Ron Messick

More to follow…