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"The Maya and later the Central Mexicans divided the motion of Venus into four intervals. They assigned an 8-day period to the disappearance at inferior conjunction [when Venus is between sun and Earth], which is close to that observed today. But, peculiarly, Maya manuscripts recorded a disappearance interval of 90 days at superior conjunction [when Venus is behind the sun], nearly double the true value. Furthermore, they assigned unequal values to the intervals as morning and evening star: 250 and 236 days, respectively. [This must be an error as 250 days refers to evening star and 236 refers to morning star.] In fact, the true intervals are equivalent at approximately 263 days. These curious intervals betray a lunar origin: the latter three are whole or half multiples of the lunar synodic month:
In practice this means that if, for example, a first-quarter moon was visible at a morning heliacal [first appearance after having been invisible due to being close to, behind of or in front of the sun] rise of Venus, then the moon's phase, on average, would be the same on the last day that morning star Venus was seen in the east. When Venus reappeared as the evening star in the west, the moon would appear in the opposite phase (last quarter)." "Timing Venus events using the lunar phase cycle, as opposed to the more familiar seasonal year, may seem strange to us, but it was what we might expect among cultures in which a lunar-based calendar preceded the solar calendar baseline we now use to mark time. This was indeed the case for our own (Roman) as well as for the Maya and many other calendars throughtout the world." (Skywatchers) |