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Sun-Earth Day Presents: Ancient Observatories, Timeless Knowledge

Technology Through Time: Issue #21, Hovenweep Castle

Long after this massive building was created to shelter them, Native Americans realized it could serve another purpose as well. Within an ancient room added almost as an afterthought, a shaft of light shines through an opening in massive wall and connects its dwellers with the sun's springtime cadence.


Hovenweep National Monument straddles the southern, Utah-Colorado border.
Latitude 37d 23' 09N
Longitude 109d 04' 49W
Altitude 5,200 feet


Tree-ring dating of timbers used in the construction of the 'Sun Room' suggest that it was added in 1277 AD about 100 years after the main structure, called the Castle, was completed. Two ports, or windows, in the large tower admit the rays from the sun into the interior room, and it has been proposed that this arrangement was used as a solar calendar. The equinox port points to the sunrise azimuth 4 days after the vernal equinox. One explanation for this is that this is the consequence of a method for establishing the equinox azimuth by counting and halving the number of days between the winter and summer solstices.



Image Gallery:

Hovenweep Castle Hovenweep Castle Hovenweep Castle Hovenweep Castle Hovenweep Castle Hovenweep Castle

Photo Credit:

Photo: Troy Cline

Technology Through Time Bulletin Board Activity

This bulletin board activity is designed to focus student attention on the role that sun watching has played in humankind's survival through time. As part of this display you may wish to use your own world map ordownload one we have created for you.

Hovenweep Castle Links

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