Editing Great Pyramid of Giza (section)

==== Alignment to the cardinal directions ====
The sides of the Great Pyramid's base are closely aligned to the four geographic (not magnetic) cardinal directions, deviating on average [[Minute and second of arc|3 minutes and 38 seconds of arc]], or about a tenth of a [[Degree (angle)|degree]].<ref>{{Cite journal|last=Dash|first=Glen|date=2012|title=New Angles on the Great Pyramid|url=http://www.aeraweb.org/wp-content/uploads/2015/01/aeragram13_2.pdf |archive-url=https://web.archive.org/web/20160402181457/http://www.aeraweb.org/wp-content/uploads/2015/01/aeragram13_2.pdf |archive-date=2016-04-02 |url-status=live|journal=Aeragram|volume=13-2|pages=10–19}}</ref> Several methods have been proposed for how the ancient Egyptians achieved this level of accuracy:

* The solar [[gnomon]] method: The shadow of a vertical rod is tracked throughout a day. The shadow line is intersected by a circle drawn around the base of the rod. Connecting the intersecting points produces an east–west line. An experiment using this method resulted in lines being, on average, 2&nbsp;minutes, 9&nbsp;seconds off due east–west. Employing a pinhole produced much more accurate results (19&nbsp;arc seconds off), whereas using an angled block as a shadow definer was less accurate (3′&nbsp;47″ off).<ref>{{Cite journal|last=Dash|first=Glen|date=2014|title=Did Egyptians Use the Sun to Align the Pyramids?|url=http://www.aeraweb.org/wp-content/uploads/2015/09/AG15_1_2.pdf |archive-url=https://web.archive.org/web/20160402200158/http://www.aeraweb.org/wp-content/uploads/2015/09/AG15_1_2.pdf |archive-date=2016-04-02 |url-status=live|journal=Aeragram|volume=15|pages=24–28}}</ref>
* The [[pole star]] method: The polar star is tracked using a movable sight and fixed plumb line. Halfway between the maximum eastern and western elongations is true north. [[Thuban]], the polar star during the Old Kingdom, was about two degrees removed from the celestial pole at the time.<ref>{{Cite web|title=How the Pyramid Builders May Have Found Their True North Part II: Extending the Line|url=http://glendash.com/blog/2014/06/20/how-the-pyramid-builders-may-have-found-their-true-north-part-ii-extending-the-line-2/|access-date=8 April 2021|archive-date=8 December 2021|archive-url=https://web.archive.org/web/20211208024645/http://glendash.com/blog/2014/06/20/how-the-pyramid-builders-may-have-found-their-true-north-part-ii-extending-the-line-2/|url-status=dead}}</ref>
* The simultaneous transit method: The stars [[Mizar]] and [[Kochab]] appear on a vertical line on the horizon, close to true north around 2500&nbsp;BC. They slowly and simultaneously shift east over time, which is used to explain the relative misalignment of the pyramids.<ref name="Spence2000"/><ref>{{Cite journal|last=Dash|first=Glen|date=2015|title=Simultaneous Transit and Pyramid Alignments: Were the Egyptians' Errors in Their Stars or in Themselves?|url=http://dashfoundation.com/downloads/archaeology/working-papers/Simultaneous_Transit.pdf|journal=Glen Dash Foundation for Archaeological Research|archive-url=https://web.archive.org/web/20200327154119/http://glendash.com/downloads/archaeology/working-papers/Simultaneous_Transit.pdf|archive-date=27 March 2020}}</ref>