Maya astronomical observations and the agricultural cycle in the postclassic Madrid codex

Research presented here demonstrates that an unusual almanac in the Madrid Codex (pages 12-18) integrates observations of the Venus cycle with eclipse events in the context of the agricultural year. Imagery in the 260-day almanac represents eclipse glyphs associated with Tzolkin dates that coordinate with eclipses visible in Yucatan during the fifteenth century, indicating the almanac dates to the Late Postclassic. The almanac also depicts seasonal events in the context of a repeating pattern of paired solar eclipses associated with observations of Venus as the evening star. Quetzalcoatl-Kukulcan's counterpart in the Madrid almanac is the Chicchan serpent, who plays the role of Venus in a sequence showing a fertile aspect of the planet linked with the 260-day agricultural cycle and the Pleiades. Clearly, Venus positions and eclipse events were closely watched in relation to the planting cycle, reflecting a form of agro-astronomy that we are only now beginning to understand.