The diagram shows how astronomical facts (equinoxes, solstices and
zenith passages of the sun) forced a structure for the year (haab)
which is 105 (= 52½ + 52½) + 260 (= 180 + 40 + 40) days. That was the
situation at the latitude of Copan.
|
vernal equinox -
zenith passage |
2 uinal |
|
zenith passage -
summer solstice |
52½ kin |
|
summer solstice
- zenith passage |
52½ kin |
|
zenith passage -
autumn equinox |
2 uinal |
|
autumn equinox -
vernal equinox |
9 uinal |
|
total |
1 haab |
(Skywatchers)
So perhaps the 260 kin period (tzolkin)
derives from this rather than from some mystic idea of 13 * 20?
|