Wonders of the Universe - Brian Cox [83]
The towers of the ruined temple of the ancient hilltop fortress at Chankillo are a remarkable sight, standing tall through the sand-laden skies of the Peruvian desert.
On the arid coastal plain of northwestern Peru lies one of South America’s greatest astronomical secrets. Few people know about the hilltop fortress at Chankillo, and even fewer visit it, but for archaeologist and astronomer alike it is both evocative and fascinating. Two and a half thousand years ago, a civilisation we know almost nothing about built a city in this inhospitable place. The grandest of the structures was a fortified temple with walls of brilliant white covered with red-painted figures. Commanding a sweeping view across the desert, the temple would have dominated the sand-laden skies, however, today all but the smallest fragments of the decorations are gone, dulled by passing centuries. The building’s location has puzzled archaeologists for many years because, while it is commanding, the hilltop site is not the best defensive position in the area, and it is unimaginable that the residents of Chankillo made a mistake when siting their fortress. Recent research has suggested that the key to understanding this place may lie not on the hilltop, but on the desert plain below.
Away from the ruined fortress and aligned north to south along the ridge of a nearby hill are thirteen towers. Recent excavations have uncovered further buildings to the east and west of the towers which archaeologists now believe to be intimately connected to this reptilian structure’s true purpose. To see why, you must stand at the western observation point at the end of a night, facing the brightening eastern horizon through the towers. I have seen many sunrises, but nothing as dramatic and evocative as a Chankillo dawn. The edge of the solar disc, reddened and distorted by air heavy with sand, suddenly flares between two of the towers on the hill, and for the briefest of moments the Sun emerges as a single sparkling diamond in the desert sky. Within seconds, the normally imperceptible rotation of our planet drags the star into full view, and you must avert your gaze as if to avoid staring into the face of a god.
The Thirteen Towers of Chankillo are more than a temple, however. It is thought that they are an ancient calendar, diligent timekeepers that have measured the passing of the days for thousands of years, outliving their creators by millennia. There is no clockwork here, no pendulums or cogs to keep the timepiece ticking; instead, time is measured using the most reliable pulse that the ancients had at their disposal – the Sun. In a beautiful piece of grand astronomical engineering, the thirteen towers are placed to mark the passing of time using the position of the sunrise on the eastern horizon. On 21 December, which in the Southern Hemisphere is the summer solstice – the longest day – the Sun rises just to the right of the most southerly tower, marking the beginning of a journey that will take it across the horizon as Earth orbits the Sun. As the year passes, the sunrise moves along the towers until, on 21 June – the shortest day – it rises just to the left of the northerly tower. So at any time of year, watching the sunrise at Chankillo would have allowed its inhabitants to determine the date within an accuracy of two or three days. I stood at the western observing point on 15 September, aware that the Sun has risen between the fifth and the sixth towers on this morning for the past two thousand years. Chankillo still works as a calendar