CAIRO, EGYPT—The Great Pyramid of Khufu and the pyramid of Khafre at Giza, and the Red Pyramid at Dahshur, were all aligned with the cardinal points within one-fifteenth of one degree. According to a report in Live Science, engineer Glen Dash thinks Egyptian engineers may have accomplished this feat by employing a shadow cast by a rod, or gnomon, on the fall equinox, when the sun shines directly on the equator and the length of day and night are nearly equal. Dash experimented with this possible technique by surveying with a rod and shadows on the fall equinox in Connecticut, and found that the degree of error was similar to that found in the alignment of the Egyptian pyramids. The sun and stars, or a combination of methods, may also have been used by ancient Egyptian engineers, he notes. To read about Dash's previous research on the pyramids, go to “The Great Parallelogram.”