The Maya, who were both intensive agriculturalists as well as consummate mathematicians, took an intense interest in the movement of the heavens. At observatories in Mayan cities such as Palenque and Chichén Itzá, Mayan astronomers used an artificial horizon – a flat, circular platform of regular size – on which they marked carefully the points at which stars, planets, the moon and sun rose and fell each year. The Mayans used these observations to create detailed calendars. We are familiar with a solar one – our 365-day calendar is based upon the length of time that it takes for the sun to complete one cycle, but many cultures also use a lunar calendar (i.e. the length of time it takes for the moon to wax and wane 12 times). The Mayans added more and more cycles to this. For instance, the planet Venus takes 584 days to return to the same spot on the rim of one of the Mayan observatories’ artificial horizons. Noticing and recording this, the Maya also developed a Venusian calendar. Finally, to these astronomical observations, the Mayans added a 260-day calendar, one that lines up with the average time from human conception to birth.
The function of this astronomy was astrology, religion, agriculture, and politics combined. The stars and planets (as were, at times, Mayan rulers) were Mayan gods. As calendars interlinked, different activities – planting, warfare, festivals, the fortunes of a particular leader – would become more or less auspicious. Astronomy via the observatory was, for the Mayans, a way of tracking how the natural world, the supernatural world, and the political world were interlinked. Today, astronomical observations and calendrical cycles still influence how present-day Maya practice indigenous religion and divination.