What is the relationship between determining the direction of the Qibla and the sun’s perpendicularity to the Holy Kaaba?

Weather of Arabia - The reason for the phenomenon of the sun perpendicular to the Holy Kaaba is due to the tilt of the Earth’s axis of rotation at an angle of 23.5 degrees, which leads to the sun apparently moving between the Tropics of Cancer to the north and Capricorn to the south, passing through the equator as the Earth rotates around the sun once a year. Perpendicularity occurs twice a year: the first in May and the second in July, when the sun is completely perpendicular over the Kaaba, causing its shadow and the shadows of all surrounding objects in Mecca to disappear.

This astronomical phenomenon is important for determining the direction of the Qibla accurately in areas far from Mecca. When observing the shadow resulting from a vertical object at the time of perpendicularity, the direction of Mecca can be determined with an accuracy equivalent to the accuracy of digital applications. In addition, this phenomenon is used to calculate the circumference of the Earth in simple, non-digital ways, which indicates the sphericity of the Earth.