Muslims perform their prayers by facing the Qibla —or the direction to the Kaaba in Mecca, Saudi Arabia. The direction of the Qibla is traditionally determined from the direction to the Sun when the Sun is directly overhead the Kaaba. If during the time the Sun is visible, it will indicate the direction of the Qibla.
If the results of the observation are drawn on the so-called ‘flat-Earth map’, the Qibla will not consistently point to the Kaaba. Only the calculation using the spherical Earth model will give us consistent results that conform to centuries of observation, from various locations on Earth. The reason is that the Earth is a sphere.
The Sun will be directly overhead Mecca on May 27-28 at 9:18 GMT and on July 15-16 at 9:27 GMT. During these times, if the Sun is visible from any location on Earth, the direction to the Sun will be the same as the direction of the Qibla.
If the Sun is not visible from a location, the Qibla can be determined from the direction of the Sun when it is overhead the antipode of Mecca. During the time, the direction away from the Sun will be the same as the direction of the Qibla. This happens on January 12-13 at 21:29 GMT and on November 28 at 21:09 GMT.
Today, a lot of Muslims use technology to determine the Qibla. Various online calculators and mobile apps for determining the Qibla rely on calculations using the spherical Earth model. And not just the Qibla: the times of prayer, the start of Ramadan, and determining the time of an eclipse prayer in advance; all require the correct understanding of spherical Earth.
In a way, it can be said that Islamic rituals depend on the correct understanding that Earth is a sphere. Even if some Muslims claim that the Earth is flat, how they perform their religious rituals tells us otherwise.
- Qibla – Wikipedia