Another feature of the 10,500 BC correlation mentioned previously suggests strongly that it is indeed not coincidental that the pyramids are laid out to mirror the skies. Due to precession, the Orion 'slides' up and down the meridian in the course of 25,920 years or one precessional cycle. It takes 12,960 years for Orion to descend from top to bottom and another 12,960 years to ascend from bottom to top again. By generating a simulation of the night sky at 10,500 BC, it was found that Al Nitak, the lowest of the three stars of the Orion belt crosses the meridian at an altitude of only 9 degrees 20' above the horizon. This is the lowest altitude it will reach in its precessional cycle. Thus, by mimicking the layout of the belt stars in the sky in 10,500 BC, the pyramids not only signifies a specific epoch but also marks the beginning of a precessional half-cycle.