and south; for the inhabited part of the earth lies in its northern region, north of the equator, which corresponds to the celestial equator and bears the same relation to both poles—the northern and the southern. Thus, the motion of the celestial sphere at that location is described as wheel-like, resembling a wheel; at the poles, it is millstone-like, resembling the motion of a millstone; and in the inhabited part of the earth, it is belt-like, resembling sword-belts.
The inhabited, populated portion of the earth is said to extend over sixty-odd degrees, a little more than one-sixth.
A detailed discussion of this belongs elsewhere. There we have presented evidence from the Quran and Sunnah, the statements of the Companions and Successors, and the other Muslim scholars who followed them, showing that the “celestial sphere” is round. Several scholars have reported the consensus of Muslim scholars on this, including Imam Abū al-Husayn ibn al-Munādī, who authored some “four hundred works” and belonged to the second generation of Ahmad’s followers; Abū Muhammad ibn Hazm; Abū al-Faraj ibn al-Jawzī; and others.
The point here is that when the sun rises over the easternmost lands, it is then either setting or approaching sunset over the westernmost lands. Its light extends ninety degrees ahead of it and ninety degrees behind it; this is the limit of its illumination. When it rises upon them, ninety degrees separate it from them, and the same applies to every land over which it rises. The astronomer distinguishes between degrees just as he distinguishes between hours, for each of the unequal, seasonal hours comprises fifteen degrees reckoned according to the time in question