The Great Pyramids at Giza have never been accurately dated. Conventional Egyptian chronologies are only accurate to within 100 years. Using a neat trick, scientists have been able to pin that date down to within a few years. When they were built, the pyramids where aligned northwards by using two stars as a guides. Over time, these stars have moved because the Earth's rotational axis "wobbles" slightly over a 26,000 year period. The orientations of the pyramids reflect this, the older pyramids are oriented slightly to the north east and the younger ones are oriented slightly to the north west. This information has been used to pin down their exact ages.
posted by lagado
on Nov 15, 2000 -