Astronomy

Prehistoric Astronomy



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According to Dr. J. McKim Malville in a Guide to Prehistoric Astronomy in the Southwest, the use of natural features in the landscape augmented by man-made structures and pictographs provided essential astronomical data about the sun to the Puebloan cultures. More speculative in natural are other features built into the landscape and shown in pictographs. With historical data, archaeologists have to think logically about what, why and how a people would use something and then establish a case for why it would work that way. This method is well-demonstrated in Dr. Malville's book.

Establishment of the Compass Directions

There's no evidence that a large stick called a gnomon used by other cultures to define the compass directions was used by Puebloan cultures, according to Dr. Malville. Yet, the stick, like the center piece of a sundial is very useful and the Puebloan cultures are very precise in laying out their homes with an North-South orientation that allows a room with protection from both the heat of summer and cold of winter. Dr. Malville explains that marking off the length of the stick all day using rocks will produce an arc. By bisecting the arc with a circle, the two endpoints of the East-West line can be built, with the North-South Direction being perpendicular to it.

What can be determined is that a star such as the North star would not have provided the accuracy of compass position that was used in constructing Puebloan homes.

Use of the Horizon to Establish the Easternmost Sunrise at the Winter Equinox

Because the Puebloan region contains many mesas, flat topped hills that rise above the plain, a horizon was available to the Puebloan cultures to record the earliest sunrises and latest sunsets for the year. The easternmost sunrise occurs at the Winter Solstice, which is also the shortest day of the year. By recording where this position occurred on the landscape with a natural feature often also marked with a pictogram, the baseline calendar was established. In addition, the sun's rise and set is also greatly slowed. A pecked basin at Piedra Del Sol marks the winter equinox, for example.

Use of the Horizon to Establish the Westernmost Sunset at the Summer Equinox

The summer equinox is also the longest day of the year and again the sun's set is greatly slowed. Like a yardstick with the winter equinox position on the right and the summer equinox on the left, the duration of the year can be marked off in regular measures. This yardstick is known as the solar ecliptic. At Piedra del Sol, a spiral pictograph is used to mark off the location for the summer equinox, for example.

Use of the Horizon to Mark Off Important Calendar Days

With the ecliptic established, key datapoints are needed by an early farming community such as when to clear fields and when to plant corn and squash. Depending on how far east a culture is located, the dominance of either the sunrises, both sunrise and sunset or the sunsets was noted by Dr. Malville. The entire horizon is marked at the Wijiji site.

Building of Kivas and Chimneys

Dr. Malville uses a Puebloan traditional text to describe the creation of a kiva, a large building constructed below ground with a circular interior and covered by a roof. Kivas are exactly built to correspond to the compass and the dome of the sky. Solar features in Kivas are noted potentially by clefts and windows that look out at the solstice sunrise or sunset. Other buildings have a notch that allows in the sunlight so someone could gauge the time of day.

Speculative Features to Record Key Astrological Events of the Time

Dr. Malville noted two pictographs that could have indicated the appearance of Halley's comet and of two supernova events at Chaco Canyon and of an eclipse of the sun at a time with marked solar flare activity and of a conjunction of Venus during a solar eclipse with a pecked out hole. The timing of the events and the building of the communities are closely correlated.

What Sites Show Solar and Astronomical Features

Chaco Canyon, Hovenweep, Mesa Verde, Yellow Jacket and Chimney Rock all show signs in the form of chipped out basins, spiral for solar equinoxes, monoliths, viewing sites and kivas of astronomical activities in the Puebloan cultures. It makes an interesting study and demonstrates the ingenuity of Prehistoric man in watching his environment.

[1] Guide to Prehistoric Astronomy in the Southwest, Dr. J. McKim Malville

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