BİRİNCİ FEN · ÜÇÜNCÜ BÂB · YEDİNCİ FASIL · İkinci Madde
Secondly, it describes the division of the Earth into five zones by means of four circles.
Know, O esteemed one, that astronomers have said: Four small circles, possessing two poles and two tropics, have divided the entire earth into five zones; each zone being the distance between two small circles or within a single circle. Thus, one of these five zones lies beneath the sun’s orbit between the two tropics, and is therefore called the “scorching zone.” Due to this extreme heat, ancients believed it uninhabited. The distance between these two tropics is forty-seven degrees, with the equator situated in its midst. These two zones are termed the "frigid belts," for they are distant from the sun’s orbit and possess intense cold; hence, ancient scholars deemed them uninhabitable. These two zones lie between the two tropic circles of the zodiacal signs, each extending twenty-three and a half degrees towards the pole. These two zones are also named after their respective poles.
The remaining regions from those two poles are known to be temperate in climate. As temperatures there generally remain moderate, they have been inhabited and cultivated. Of these, the northern portion is bounded by the Tropic of Cancer and the north turning place of the zodiacal signs; while the southern portion extends from the Tropic of Capricorn to the south turning place of the zodiacal signs. The latitude distance of each of these is measured as forty-three degrees.
The inhabitants of these five zones are distinguished from one another according to their shadows and locations. Those in the frigid zone are called "rahavî" (millstone people), because their shadows rotate like a millstone on the horizon. The inhabitants of the temperate zone are termed “hamâilî” (sword belt people), for their shadow leans sideways like a sword belt at midday. The inhabitants of the scorching zone are known as "zâtü’z-zılleyn" (possessors of two shadows), because the shadows of those on the equator sometimes fall south and sometimes north at midday. When the luminous sun is twice in a year at the equinox point, it reaches its zenith and eliminates shadows at noon. It is when this region is furthest from the sun that it reaches the tropic.
Those beneath the two tropics have the luminous sun reach their zenith once a year, eliminating shadows at noon. And it has been observed that for the people of the zone between the two tropics, the pole of the world is always midday.
The opposite pole of the world remains perpetually in shadow; its shadows are singular. In terms of place and location, all regions are divided into three parts: one group resides in the equatorial region, where all places from west to east are arranged within a single turning point and latitude; a second group is arranged at equal distances from the equator on either side; and a third group lies parallel to the equator on both sides, one at the head of the world (zenith) and the other at its foot (nadir). The truth is only known by God, exalted be He.