Aztec Calendar Stone.jpg

More on the Mayan 13 Moons calendar

What is the Maya Calendar? 
The Maya Calendar is a system of distinct calendars and almanacs used by the Maya civilization of pre-Columbian Mesoamerica, and by some modern Maya communities in highland Guatemala.These calendars can be synchronized and interlocked, their combinations giving rise to further, more extensive cycles. The essentials of the Maya calendric system are based upon a system which had been in common use throughout the region, dating back to at least the 6th century BC. It shares many aspects with calendars employed by other earlier Mesoamerican civilizations, such as the Zapotec and Olmec, and contemporary or later ones such as the Mixtec and Aztec calendars.

Although the Mesoamerican calendar did not originate with the Maya, their subsequent extensions and refinements of it were the most sophisticated. Along with those of the Aztecs, the Maya calendars are the best-documented and most completely understood.
In the Maya mythological tradition, as documented in Colonial Yucatec accounts and reconstructed from Late Classic and Postclassic inscriptions, the deity Itzamna (In Yucatec Maya mythology, Itzamna was the name of an upper god and creator deity thought to be residing in the sky) is frequently credited with bringing the knowledge of the calendar system to the ancestral Maya, along with writing in general and other foundational aspects of Maya culture.

The Pyramid of Kukulkan at Chichén Itzá, constructed circa 1050 was built during the late Mayan period, when Toltecs from Tula became politically powerful.
The pyramid was used as a calendar: four stairways, each with 91 steps and a platform at the top, making a total of 365, equivalent to the number of days in a calendar year.
The Maya calendar was adopted by the other Mesoamerican nations, such as the Aztecs and the Toltec, which adopted the mechanics of the calendar unaltered but changed the names of the days of the week and the months.

The Maya calendar uses three different dating systems in parallel, the Long Count, the Tzolkin (divine calendar), and the Haab (civil calendar).
Of these, only the Haab has a direct relationship to the length of the year.
A typical Mayan date looks like this: 12.18.16.2.6, 3 Cimi 4 Zotz.

 
                                                                                                         (Aztec Calendar)

Did the Mayas thought a Year was 365 days?
Although there were only 365 days in the Haab year, the Mayas were aware that a year is slightly longer than 365 days.

When the Long Count was put into motion, it was started at 7.13.0.0.0, and 0 Yaxkin corresponded with Midwinter Day, as it did at 13.0.0.0.0 back in 3114 B.C.E. The available evidence indicates that the Mayas estimated that a 365-day year precessed through all the seasons twice in 7.13.0.0.0 or 1,101,600 days.

We can therefore derive a value for the Mayan estimate of the year by dividing 1,101,600 by 365, subtracting 2, and taking that number and dividing 1,101,600 by the result, which gives us an answer of 365.242036 days, which is slightly more accurate than the 365.2425 days of the Gregorian calendar.

In the ancient times, the Mayans had a tradition of a 360-day a year. But by the 4th century B.C.E. ,they took a different approach than the Europeans or Asians. They maintained three different calendars at the same time. In one of them, they divided a 365-day year into (18) 20-day months followed by a 5-day period that was part of no month. The day period was considered to be unlucky.