Stonehenge

Stonehenge

Fig. 1.1 . The ancient stone pillars of Stonehenge in southern England, shown in this photograph, frame the rising Sun. This monument was used to find midsummer and midwinter four thousand years ago before the invention of writing and the calendar. The Sun rises at different points on the horizon during the year, reaching its most northerly rising on Midsummer Day (summer solstice on June 21). After this, the rising point of the Sun moves south along the horizon until it reaches its most southerly rising on Midwinter Day (winter solstice on December 22). An observer located at the center of the main circle of stones at Stonehenge watched midsummer sunrise over a marker stone located outside the circle; other stones within the circle framed midwinter sunrise and sunset. (Courtesy of Owen Gingerich.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University