About 2,000 years ago in the Ohio Valley, the indigenous American Indians must have had certain magi carefully observing the heavens because they aligned their most magnificent earthen monuments to the rising and setting of the Sun and Moon.
     The Newark Earthworks (Ohio, USA) showcase how astronomical alignments were woven into the designs of Hopewell culture architecture. They extend across nearly 5 square miles and include the Great Circle, the Octagon Earthworks, a large square enclosure and an oval earthwork surrounding numerous burial mounds. Only the Great Circle and the Octagon Earthworks survive largely intact.
     In 1982, Ray Hively and Robert Horn, professors at Earlham College in Richmond, Ind., showed that the Octagon Earthworks encoded the 18.6-year cycle of moonrises and moonsets into its walls. The duo's latest research, published this year, suggests the Newark magi made their incredibly precise astronomical observations from the tops of prominent hills surrounding the earthworks.
     Hively and Horn identified four key hilltops overlooking the earthworks that offer unobstructed views to the horizon. From one of these you can see directly across the center of the Octagon Earthworks to where the Moon rises at its northernmost point on the eastern horizon. From that same hilltop, you can look across the center of Newark's Great Circle to a point about 14 degrees to the south, which marks the minimum northern moonrise. The three other prominent hilltops provide vantage points for observing alignments of key elements of the earthworks with the southern maximum and minimum moonrises and the four moonsets that, together with the four moonrise alignments, encompass the entire 18.6-year lunar cycle.
     Astonishingly, sightlines between these four hilltops mark the sunrises and sunsets on both the summer and winter solstices. Those alignments intersect at the approximate center of the earthworks at a point that is midway between the Great Circle and the large circle at the Octagon Earthworks.
     These observations make it clear that the Newark Earthworks represent an unprecedented interweaving of geometry, astronomy and landscape into monumental architecture on a mind-boggling scale. At the Midwest Archaeological Conference in November, Hively and Horn presented evidence to suggest that the Hopewellian earthworks in the Scioto Valley were designed in a similar way.

Edited from The Columbus Dispatch (22 December 2013)