Volume 20

The Zenith Sun as an Organizing Principle of the Constructed Sacred Space and Calendrics of Central Mexico

Harold H. Green

Abstract

Speculations that the Mesoamerican 260-day tonalpohualli may have a direct relationship to the 260-day interval between solar zenith passages that uniquely occur within a narrow latitudinal band just south of 15 degrees north latitude (the '260-day band') are supported by evidence from extensive and systematic documentation of orientations at sites throughout Central Mexico. Sites were located and important structures within those sites were oriented from as early as the early 3rd century BCE in accordance with a horizon reference system defined by the dates of the zenith and nadir passages and related calendrically significant solar events of that 260-day band. Subterranean chambers and other constructed devices have been identified that enabled precise determination of the actual dates of those zenith passages and thereby permitted calibration of the horizon reference system from one solar cycle to the next. In these respects, the zenith sun of the 260-day band served as an organizing principle of the constructed space and calendrics of Central Mexico.