Question

why do we place the gnomon in the north direction ?​

Answer 1

Then you just draw a line from the Gnomon to the point of intersection of the two circles, as shown. This line defines the North-South direction with very good precision. This may have been the method that enabled the ancient Egyptians to align the pyramids so accurately to the North-South-East-West directions.

Answer 2

Explanation:

you just draw a line from the Gnomon to the point of intersection of the two circles, as shown. This line defines the North-South direction with very good precision. This may have been the method that enabled the ancient Egyptians to align the pyramids so accurately to the North-South-East-West directions.