By the 9th century, many Muslim scholars took it for granted that the Earth was a sphere. The proof, said astronomer Ibn Hazm, “is that the Sun is always vertical to a particular spot on Earth”. It was 500 years before that realisation dawned on Galileo. The calculations of Muslim astronomers were so accurate that in the 9th century they reckoned the Earth’s circumference to be 40,253.4km – less than 200km out. The scholar al-Idrisi took a globe depicting the world to the court of King Roger of Sicily in 1139.
In early times, people believed that the earth is flat. For centuries, men were afraid to venture out too far, lest they should fall off the edge. Sir Francis Drake was the first person who proved that the earth is spherical when he sailed around it in 1597.
Consider the following Qur’aanic verse regarding the alternation of day and night:
“Seest thou not that Allah merges Night into Day And He merges Day into Night?” [Al-Qur’aan 31:29]
Merging here means that the night slowly and gradually changes to day and vice versa. This phenomenon can only take place if the earth is spherical. If the earth was flat, there would have been a sudden change from night to day and from day to night.
The following verse also alludes to the spherical shape of the earth:
“He created the heavens And the earth In true (proportions): He makes the Night Overlap the Day, and the Day Overlap the Night.” [Al-Qur’aan 39:5]
The Arabic word used here is Kawwara meaning ‘to overlap’ or ‘to coil’– the way a turban is wound around the head. The overlapping or coiling of the day and night can only take place if the earth is spherical.
Naik, Zakir. The Quran and Modern Science: Compatible or Incompatible. (p.10). http://www.islamicweblibrary.com/wp-content/uploads/2019/03/qms.pdf#page=10