Stela 10, Copan, Honduras When looking through the window of Temple 22 toward the western horizon at Copan, Honduras, in the Spring, the sun sets behind Stela 10 sixteen days after Vernal Equinox at an orientation of 276*45'00". Four days later, the sun reaches the mid-line of the window at an orientation of 278*25'00. This second day always falls 20 days after Vernal Equinox and 20 days before solar zenith passage, when the sun is directly overhead at noon, and so precisely, in fact, that vertical objects do not cast a visible shadow at that time. This same sequence, but in reverse order, also occurs in the Fall, when the sun returns to these same orientations relative to solar zenith passage and Autumnal Equinox then.
During the Classic period, specifically when the ruler who built Temple 22 at Copan (18-Rabbit) was acknowledged as guardian of the World Tree for the people there, the relevant events for the sun's motion along the western horizon occurred in the following sequence in the Maya calendar