Archaeology Magazine - March/April 1979 - 51

Yucatán, the extreme rise and set positions of
Venus in approximately a.d. 750 can be marked at
both the Governor's Palace and the House of the
Magician. At this site, Aveni paid particular
attention to buildings that do not seem to fit into
the overall city plan because of their unusual shapes
or orientations. From the time of the earliest
Spanish explorations, historical documents mention
the orientation of some buildings for astronomical
happenings. Sometimes, however, the completed
structures did not face exactly where intended.
Montezuma is said to have wished to pull down the
temple of the Aztec tribal war god Huitzilopochtli
at Tenochtitlan and rebuild it because it was slightly
out of alignment. At Monte Alban in Mexico,
Building J sits at an angle to the basic layout of the
city; one end is pointed, giving the structure a
shape rather like an arrowhead. From the doorway
looking out in a perpendicular direction, the view
faces the point of heliacal rising of the first
magnitude star Capella, an event which preceded
the sun's rise on the day of its zenith passage. The
entrance of Building P faces the same direction; by
looking through a vertical shaft inside the house,
the zenith passage of the sun could be observed.
The Castillo at the Maya center of Chichen
Itza provides a fine example of the clever use of
shadows in Mesoamerican architecture. Although
known to local people, it was not until J.J. Rivard
reported it in 1970 that this phenomenon was
brought to the attention of archaeoastronomers.
About an hour before sunset on the evening of the
equinoxes, the northwest corner of the building
casts a shadow down the western side of its north
stairway. The wavy line of this shadow provides a
body for a stone serpens head at the lower end
of the balustrade, marking this day's special
importance as the midway point between the
longest and shortest days of the year.
^Vlthough archaeoastronomy in the Americas has
concentrated on the high civilizations of
Mesoamerica, they were not the only native
American communities interested in the heavens.
The Incas of South America had a 12-month
calendar and, according to an early chronicler, the
beginnings of the months were determined by
observing a set of pillars on the horizon near
Cuzco, Peru. Even today among the Pueblo peoples
of the Southwest, there are sunwatchers appointed
to note the times of the solstices, which are
important in the annual ceremonial cycle. Among
the Hopi of First Mesa, the Sun Chief, who is
believed to represent Father Sun, is in charge of
scheduling ceremonies from after the summer
solstice until the winter solstice; the leader of the

Flute Society, representing Mother Earth, takes
over for the other half of the year. The movements
of the Morning and Evening Stars, the Pleiades,
Orion and the Great Dipper are also watched and
even the Milky Way and stars such as Aldebaran
play a part in rituals. Indeed, interest in the
heavens can be traced back to the thirteenth
century after Christ or earlier in the astronomical
alignment of pueblo kivas or underground
chambers, the Anasazi ruins in Pueblo Bonito, the
circular Casa Rinconada ruin in Chaco Canyon,
New Mexico, or the square towers of Hovenweep
National Monument on the Colorado- Utah border.
A more intriguing and difficult problem
in the southwest region of the United States is
deciphering possible celestial meanings for Indian
pictographs. Some are known to be clan symbols or,
in the case of a handprint, to indicate that a
specified duty had been performed. But others
seem to be sky maps. It has been suggested that
the combination of crescent and circle found in a
number of places may well represent a visual
record of the Crab Nebula supernova of a.d. 1054,
since the supernova would have appeared on the
eastern horizon in approximately the same
relationship to the crescent moon just before dawn
on the morning of July 5th of that year.
Several hundred miles to the north a different
kind of astronomical monument appears. Known as
the medicine wheel, it is characterized by a number
of lines made of small stones that radiate out from
a central ring or cairn. "Medicine" was a word
commonly used by Indians to indicate magical
power or the supernatural. Although a half dozen
examples are scattered from northern Colorado to
the Canadian border, most medicine wheels are
found on the grassy plains of Alberta and
Saskatchewan, where at least 40 have been
identified so far. The best example is the so-called
Big Horn Medicine Wheel which lies atop Medicine
Mountain between Sheridan and Lovell, Wyoming.
Here 28 spokes made up of small stones radiate out
from a central cairn. An oval of similar small stones
marks the outside edge of the wheel. Five more
cairns lie along this edge, and a seventh cairn rests
on the end of an extended spoke on the southwest.
John A. Eddy of the High Altitude Observatory in
Boulder, Colorado, has determined that by sighting
across the central cairn from the outlying
southwestern cairn it would have been possible to
watch the sunrise on the summer solstice. From
another cairn on the southeastern side, the central
cairn marked the direction of sunset on the same
day. From yet another cairn on the western side of
the wheel, the central cairn and two of those on the
rim faced the heliacal risings of Aldebaran, Rigel
and Sirius. These constellations herald the solstice

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Archaeology Magazine - March/April 1979

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