How was the phenomenon of the sun perpendicular to the Kaaba used to determine the direction of the qiblah?

Weather of Arabia - The phenomenon of the sun perpendicular to the Kaaba occurs twice a year, the first is during the month of May, when the sun apparently moves north of the equator towards the Tropic of Cancer, when the sun passes over the latitude of Makkah Al-Mukarramah (21.425 degrees north), while it is The second time is during the month of July, when the sun returns in its apparent movement towards the south from the Tropic of Cancer to the equator, and passes over the latitude of Makkah Al-Mukarramah again.

The shadow of the honorable Kaaba and the shadows of all bodies in Makkah Al-Mukarramah disappear at the moment of perpendicularity, when the sun is at its maximum height, and at the same time the sun is tilted in the sky of distant regions.

How was the sun perpendicular to the Kaaba used to determine the direction of the qiblah?

The ancients used the phenomenon of the sun perpendicular to the Kaaba to determine the direction of the qiblah in areas geographically far from Makkah Al-Mukarramah in the Arab and Islamic countries and areas where the sun is above the horizon, and it is a simple method, but it is not less accurate in its accuracy than modern monitoring techniques, by planting a piece of wood Or the plastic perpendicular to the ground and the shadow is monitored, and the direction of the qiblah is on the opposite side of the shadow, so that the extension of the shadow points to the location of the Kaaba, knowing that this method is not useful for areas such as Jeddah and Taif due to their location close to Makkah Al-Mukarramah.

It is also worth noting the use of the phenomenon of the sun's perpendicularity in calculating the circumference of the Earth by using some simple rules in geometry, an old method dating back more than 2000 years that proved the sphericality of the Earth.

Why does the phenomenon of the sun perpendicular to the Kaaba occur?

The phenomenon of the sun’s perpendicularity occurs because the location of the Kaaba is between the equator and the Tropic of Cancer. During the apparent movement of the sun across the sky, it becomes straight with the Kaaba as it moves from the equator to the Tropic of Cancer during the month of May, when the first perpendicularity occurs.

When the sun returns south to the equator from the Tropic of Cancer in July, the second perpendicularity occurs. And the regions located in latitudes less than 23.5 degrees north and south all witness the phenomenon of perpendicularity twice a year, but at different times depending on the latitude of that place, and it is characterized by a few places confined between the equator and the tropics of Cancer and Capricorn.