Equinoxes and solstices, and other elements that oriented Mesoamerican buildings

The Mesoamerican cultures were great observers of the celestial vault and built temples and pyramids concerning equinoxes, solstices, or the zenithal passage of the Sun, but they also erected structures to measure time, to indicate important dates of their calendar, through their solar alignment.

This was affirmed by Jesús Galindo Trejo, a member of UNAM's Institute of Aesthetic Research, who 31 years ago was invited to participate in the multidisciplinary project Pre-Hispanic Mural Painting in Mexico, under the direction of Dr. Beatriz de la Fuente. Since then he has been studying the orientation of buildings in Teotihuacan, Oaxaca, in the Mayan region, the Huasteca area, and other areas of Central Mexico.

The objective was that, from Astronomy, he could help to understand if the orientation of the structures with mural paintings pointed to some celestial object that could contribute to a better understanding of the pictorial message. "The idea was to bring together the knowledge of the art historian, the archaeologist, the anthropologist, the linguist, the epigrapher, the biologist, the astronomer, to analyze pre-Hispanic mural painting in Mexico," he said.

An example of the studies he has carried out is those of the Temple of the Great Tables, located in the eastern part of the central plaza of Chichén Itzá. It is a building approximately 10 meters high with a staircase facing west, the sunset.

This building receives this name because in its upper part it has two chambers and at the bottom of the innermost one, there is an altar with large stones, which is supported by sculptures of characters identified as "bacabs", deities that held the sky. Several carved columns probably represent priests or warriors.

The building has a substructure or interior building with typical Mayan vaults and mural paintings, representations of feathered serpents with large jaws and beaks, in bright colors: blue, green, yellow, and red. The feathered serpent is a constant concept in Mesoamerica, linked to both the god Quetzalcoatl and Kukulkan.

The solar alignment of this temple is registered in the sunset of May 15 and July 26, dates that do not coincide with those of particular astronomical phenomena but are related to the beginning of the Mayan New Year. The sunrise alignment happens on November 23 and 18.

"The source of all this is measurements and calculations. Determining dates of alignment of architecture is just a tool to understand the ritual conduct of the priests, who decided that a building was directed towards that direction and not another. Then, it is necessary to investigate its cultural meaning and for it the information coming from codices, ethnohistoric sources, as the chronicles of the missionaries or the conquerors are important" explained the specialist in Archaeoastronomy of Prehispanic Mexico.

Calendar, gift of the gods

In this case, the Relationship of the things of Yucatan, written by Fray Diego de Landa, is an essential source because it helps to better understand innumerable aspects of the Maya culture. In 1566 the religious noted that the New Year in that part of the Maya region began on July 16, in the Julian calendar; in the current Gregorian calendar, it corresponds to July 26.

Father Landa also detailed that the solar calendar was conformed by 18 scores, plus five days and simultaneously ran a ritual calendar of 260 days, organized as 20 trecenas. Both calendars began at the same time, but 52 years of 365 days had to pass for them to coincide and begin again, synchronously. "In this period of years the ritual calendar contemplated 73 cycles, that is to say: 52 x 365 equals 73 x 260".

The religious chronicler described the festivities that took place in those periods and the sixth twenty, called Xul -which today corresponds to November 3 to 22- a great ceremony dedicated to Kukulkan was held. On the 16th of Xul, the Temple of Kukulkan was visited and a new fire was lit. It coincides precisely with November 18, the day of the alignment, in the morning, of the Temple of the Great Tables.

From May 15 to July 26 there are 73 days, a fundamental calendrical number. May 15 is also eleven trecenas after the winter solstice. "The 13th can be considered as the essential brick on which the whole Mesoamerican calendrical monument is erected." Besides 73 and 13, the numbers 18, 20, 52, 65, and 260 are crucial.

"The solar alignments of the main Mesoamerican architectural structures occur on certain dates that have to do with the structure of the calendar. Sometimes they are five times 13, four times 13; or 73 or 260.

These dates are generated using the solstices as natural pivots and from then on, the periods of days expressed by the fundamental numbers are counted; from the Olmec to the Mexica and beyond, this way of measuring time prevailed and, of course, the possibility of pyramids directed to the equinox, to the solstices, was not excluded.

For Mesoamerican cultures, the calendar was not the invention of a Mayan or Olmec sage, but the gods. At some point, ancient gods would have gathered to invent time and organize it in the form of a calendar. Then, other deities would have given it to man for the proper functioning of society.

The results of their research, including those related to the buildings and their relationship with important dates in the Mesoamerican calendar, will be published soon, in a book that gathers the investigations of all the participants in the project.

The university expert affirmed that after three decades, the project The pre-Hispanic mural painting in Mexico, today under the direction of researcher María Teresa Uriarte Castañeda, continues to bear fruit and contributes to a greater knowledge of one of the most sublime artistic expressions of Mexican culture.