the sun to its setting. The week, however, is a numerical unit, based on the six days in which Allah created the heavens and the earth, then rose over the Throne.

Thus, a balance is achieved between the sun and the moon: the day and the week are reckoned by the sun’s course, while the month and the year are reckoned by the moon’s course. Through both, the reckoning is complete. In light of this, His words “so that you may know” may be understood as referring back to “made,” meaning that He made the sun and the moon for all these purposes.

As for His words, Most High:

“And He made the night for rest, and the sun and the moon for reckoning,”

and His words:

“The sun and the moon follow a precise reckoning,”

some have said that the word husbān derives from calculation. Others have interpreted it as a turning like that of a millstone—that is, the rotation of the celestial sphere. This is a matter concerning which there is no disagreement. Indeed, the Quran and Sunnah indicate, and the scholars of the Muslim community unanimously affirm, the same conclusion maintained by specialists in astronomical calculation: that the celestial spheres are round, not flat.