The planet Venus is the third brightest regularly visible object in the skies, behind the sun and moon. Its cycle of morning and evening appearances was well known to the ancient Mesoamericans, partly because it seemed to fit naturally with other astronomical cycles, in that five Venus cycles exactly equaled eight year-cycles of 365 days. In fact, five Venus cycles do not quite equal eight years, and we would view the near-coincidence of these two periods merely as an accident of nature. The ancient Mesoamericans, on the other hand, saw it as a significant property of the cosmos and this had two far-reaching consequences. The first was that they, and particularly the Maya, could integrate cycles of Venus with ease into the other in-termeshing cycles of their calendar. Direct evidence of the care with which the synodic cycles of Venus were observed by the Maya comes from the Dresden Codex, where the motions of the planet are carefully tabulated and correlated with other astronomical cycles. The heliacal rising of Venus was probably the most significant event to the Maya, and certainly a time of dread for the Aztecs.
The second consequence was that Venus appeared to have a relationship with the seasons, even though a particular seasonal configuration of Venus would only recur after eight years, and so Venus became strongly associated with rain, fertility, and maize. It also appears to have become strongly associated with warfare and ritual sacrifice, with military campaigns carefully timed according to Venus-related prognostications. The two are related, since one of the main purposes of human sacrifice was to petition the gods for rain. There was also a clear association between Venus and the sacred ballgame played throughout Mesoamerica; this is evident from the common occurrence of Venus symbols both in depictions of the game in codices and on the garments and body decoration worn by the players themselves.
