Kate San's study, published in Nature, shows that the ancients lined up the pyramids with two stars whose alignment was only true around 4,500 years aqo.which makes it possible to improve the margin of error in the archaeological chronology of ancient Egypt, from plus or minus 100 years to only five years, which makes it possible to pinpoint what people probably think was the start of construction of Khufu's Great Pyramid at Giza to around the year 2467 BC.